Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Continuous-light tolerance in tomato is graft-transferable
    Vélez Ramírez, A.I. ; Ieperen, W. van; Vreugdenhil, D. ; Millenaar, F.F. - \ 2015
    Planta 241 (2015)1. - ISSN 0032-0935 - p. 285 - 290.
    lycopersicon-esculentum - plants - temperature - photosynthesis - rootstock - increase - growth - injury - xylem - fruit
    Continuous light induces a potentially lethal injury in domesticated tomato (Solanum lycopersicum) plants. Recently, continuous-light tolerance was reported in several wild tomato species, yet the molecular mechanisms underpinning tolerance/sensitivity are still elusive. Here, we investigated from which part of the plant continuous-light tolerance originates and whether this trait acts systemically within the plant. By exposing grafted plants bearing both tolerant and sensitive shoots, the trait was functionally located in the shoot rather than the roots. Additionally, an increase in continuous-light tolerance was observed in sensitive plants when a continuous-light-tolerant shoot was grafted on it. Cultivation of greenhouse tomatoes under continuous light promises high yield increases. Our results show that to pursuit this, the trait should be bred into scion rather than rootstock lines. In addition, identifying the nature of the signal/molecule(s) and/or the mechanism of graft-induced, continuous-light tolerance can potentially result in a better understanding of important physiological processes like long-distance signaling.
    Fluorescence in situ hybridization and optical mapping to correct scaffold arrangement in the tomato genome
    Shearer, L.A. ; Anderson, L.K. ; Jong, H. de; Smit, S. ; Goicoechea, J.L. ; Roe, B.A. ; Hua, A. ; Giovannoni, J.J. ; Stack, S.M. - \ 2014
    G3 : Genes Genomes Genetics 4 (2014)8. - ISSN 2160-1836 - p. 1395 - 1405.
    extended dna fibers - zea-mays l. - lycopersicon-esculentum - pachytene chromosomes - synaptonemal complexes - 2-dimensional spreads - solanaceous plants - solanum pennellii - multicolor fish - linkage maps
    The order and orientation (arrangement) of all 91 sequenced scaffolds in the 12 pseudomolecules of the recently published tomato (Solanum lycopersicum, 2n = 2x = 24) genome sequence were positioned based on marker order in a high-density linkage map. Here, we report the arrangement of these scaffolds determined by two independent physical methods, bacterial artificial chromosome–fluorescence in situ hybridization (BAC-FISH) and optical mapping. By localizing BACs at the ends of scaffolds to spreads of tomato synaptonemal complexes (pachytene chromosomes), we showed that 45 scaffolds, representing one-third of the tomato genome, were arranged differently than predicted by the linkage map. These scaffolds occur mostly in pericentric heterochromatin where 77% of the tomato genome is located and where linkage mapping is less accurate due to reduced crossing over. Although useful for only part of the genome, optical mapping results were in complete agreement with scaffold arrangement by FISH but often disagreed with scaffold arrangement based on the linkage map. The scaffold arrangement based on FISH and optical mapping changes the positions of hundreds of markers in the linkage map, especially in heterochromatin. These results suggest that similar errors exist in pseudomolecules from other large genomes that have been assembled using only linkage maps to predict scaffold arrangement, and these errors can be corrected using FISH and/or optical mapping. Of note, BAC-FISH also permits estimates of the sizes of gaps between scaffolds, and unanchored BACs are often visualized by FISH in gaps between scaffolds and thus represent starting points for filling these gaps
    Chromosomal organizations of major repeat families on potato (Solanum tuberosum) and further exploring in its sequenced genome
    Tang, X. ; Datema, E. ; Olortegui Guzman, M.C. ; Boer, J.M. de; Eck, H.J. van; Bachem, C.W.B. ; Visser, R.G.F. ; Jong, H. de - \ 2014
    Molecular Genetics and Genomics 289 (2014)6. - ISSN 1617-4615 - p. 1307 - 1319.
    ty1-copia group retrotransposons - species-specific sequences - repeated dna-sequences - in-situ hybridization - somatic hybrids - lycopersicon-esculentum - satellite repeat - repetitive dna - transposable elements - metaphase chromosomes
    One of the most powerful technologies in unraveling the organization of a eukaryotic plant genome is high-resolution Fluorescent in situ hybridization of repeats and single copy DNA sequences on pachytene chromosomes. This technology allows the integration of physical mapping information with chromosomal positions, including centromeres, telomeres, nucleolar-organizing region, and euchromatin and heterochromatin. In this report, we established chromosomal positions of different repeat fractions of the potato genomic DNA (Cot100, Cot500 and Cot1000) on the chromosomes. We also analysed various repeat elements that are unique to potato including the moderately repetitive P5 and REP2 elements, where the REP2 is part of a larger Gypsy-type LTR retrotransposon and cover most chromosome regions, with some brighter fluorescing spots in the heterochromatin. The most abundant tandem repeat is the potato genomic repeat 1 that covers subtelomeric regions of most chromosome arms. Extensive multiple alignments of these repetitive sequences in the assembled RH89-039-16 potato BACs and the draft assembly of the DM1-3 516 R44 genome shed light on the conservation of these repeats within the potato genome. The consensus sequences thus obtained revealed the native complete transposable elements from which they were derived
    The Tomato spotted wilt virus cell-to-cell movement protein (NSM) triggers a hypersensitive response in Sw-5 containing resistant tomato lines and Nicotiana benthamiana transformed with the functional Sw-5b resistance gene copy.
    Hallwass, M. ; Silva de Oliveira, A. ; Dianese, E.C. ; Lohuis, D. ; Boiteux, L.S. ; Inoue-Nagata, A.K. ; Resende, R.O. de; Kormelink, R.J.M. - \ 2014
    Molecular Plant Pathology 15 (2014)9. - ISSN 1464-6722 - p. 871 - 880.
    mosaic-virus - lycopersicon-esculentum - nonstructural protein - capsicum-chinense - coat protein - plant-cells - rna segment - tswv - tospovirus - tobacco
    Although the Sw-5 gene cluster has been cloned, and Sw-5b has been identified as the functional gene copy that confers resistance to Tomato spotted wilt virus (TSWV), its avirulence (Avr) determinant has not been identified to date. Nicotiana tabacum SR1 plants transformed with a copy of the Sw-5b gene are immune without producing a clear visual response on challenge with TSWV, whereas it is shown here that N.benthamiana transformed with Sw-5b gives a rapid and conspicuous hypersensitive response (HR). Using these plants, from all structural and non-structural TSWV proteins tested, the TSWV cell-to-cell movement protein (NSM) was confirmed as the Avr determinant using a Potato virus X (PVX) replicon or a non-replicative pEAQ-HT expression vector system. HR was induced in Sw-5b-transgenic N.benthamiana as well as in resistant near-isogenic tomato lines after agroinfiltration with a functional cell-to-cell movement protein (NSM) from a resistance-inducing (RI) TSWV strain (BR-01), but not with NSM from a Sw-5 resistance-breaking (RB) strain (GRAU). This is the first biological demonstration that Sw-5-mediated resistance is triggered by the TSWV NSM cell-to-cell movement protein.
    A single locus confers tolerance to continuous light and allows substantial yield increase in tomato
    Vélez Ramírez, A.I. ; Ieperen, W. van; Vreugdenhil, D. ; Poppel, P.M.J.A. van; Heuvelink, E. ; Millenaar, F.F. - \ 2014
    Nature Communications 5 (2014). - ISSN 2041-1723
    differential expression analysis - photosystem-ii - lycopersicon-esculentum - greenhouse tomato - dependent phosphorylation - chlorophyll fluorescence - arabidopsis-thaliana - gene-expression - air humidity - plants
    An important constraint for plant biomass production is the natural day length. Artificial light allows for longer photoperiods, but tomato plants develop a detrimental leaf injury when grown under continuous light—a still poorly understood phenomenon discovered in the 1920s. Here, we report a dominant locus on chromosome 7 of wild tomato species that confers continuous light tolerance. Genetic evidence, RNAseq data, silencing experiments and sequence analysis all point to the type III light harvesting ¿chlorophyll a/b binding protein 13 (¿CAB-13) gene as a major factor responsible for the tolerance. In Arabidopsis thaliana, this protein is thought to have a regulatory role balancing light harvesting by photosystems I and II. Introgressing the tolerance into modern tomato hybrid lines, results in up to 20% yield increase, showing that limitations for crop productivity, caused by the adaptation of plants to the terrestrial 24-h day/night cycle, can be overcome.
    Capturing flavors from Capsicum baccatum by introgression in sweet pepper
    Eggink, P.M. ; Tikunov, Y.M. ; Maliepaard, C.A. ; Haanstra, J.P.W. ; Rooij, H. de; Vogelaar, A. ; Gutteling, E.W. ; Freymark, G. ; Bovy, A.G. ; Visser, R.G.F. - \ 2014
    Theoretical and Applied Genetics 127 (2014)2. - ISSN 0040-5752 - p. 373 - 390.
    plastid compartment size - lycopersicon-esculentum - volatile compounds - anthracnose resistance - chemical-composition - gas-chromatography - sensory evaluation - mass-spectrometry - candidate gene - essential oils
    The species Capsicum baccatum includes the most common hot peppers of the Andean cuisine, known for their rich variation in flavors and aromas. So far the C. baccatum genetic variation remained merely concealed for Capsicum annuum breeding, due to post-fertilization genetic barriers encountered in interspecific hybridization. However, to exploit the potential flavor wealth of C. baccatum we combined interspecific crossing with embryo rescue, resulting in a multi-parent BC2S1 population. Volatile and non-volatile compounds plus some physical characters were measured in mature fruits, in combination with taste evaluation by a sensory panel. An enormous variation in biochemical composition and sensory attributes was found, with almost all traits showing transgression. A population-specific genetic linkage map was developed for QTL mapping. BC2S1 QTLs were validated in an experiment with near-isogenic lines, resulting in confirmed genetic effects for physical, biochemical and sensory traits. Three findings are described in more detail: (1) A small C. baccatum LG3 introgression caused an extraordinary effect on flavor, resulting in significantly higher scores for the attributes aroma, flowers, spices, celery and chives. In an attempt to identify the responsible biochemical compounds few consistently up- and down-regulated metabolites were detected. (2) Two introgressions (LG10.1 and LG1) had major effects on terpenoid content of mature fruits, affecting at least 15 different monoterpenes. (3) A second LG3 fragment resulted in a strong increase in Brix without negative effects on fruit size. The mapping strategy, the potential application of studied traits and perspectives for breeding are discussed.
    Aroma volatile release kinetics of tomato genotypes measured by PTR-MS following artificial chewing
    Farneti, B. ; Alarcón, A. ; Cristescu, S.M. ; Costa, G. ; Harren, F.J.M. ; Holthuysen, N.T.E. ; Woltering, E.J. - \ 2013
    Food Research International 54 (2013)2. - ISSN 0963-9969 - p. 1579 - 1588.
    reaction-mass spectrometry - flavor release - lycopersicon-esculentum - in-vitro - physiological-parameters - quantitative-analysis - model mouth - cultivars - fruit - mastication
    The aim of this study was to develop an analytical system to study the tomato aroma profile. An artificial chewing device coupled to a PTR-MS was developed to mimic, as close as possible, the release of volatiles during chewing in the human mouth and the retronasal olfaction perception. VOC profiles of 9 tomato lines, selected based on flavor characteristics by a sensory panel, were acquired by both a PTR-MS system following artificial chewing and by SPME–GC–MS and compared to the quantitative descriptive analysis (QDA) measured by the trained sensory panel. Based on multivariate statistical analysis, data obtained by the PTR-MS system showed a better correlation to the outcome of the QDA than SPME–GC–MS, especially for the descriptive parameters “tomato fragrance” and “tomato flavor”. The great advantage of such an analytical system was the possibility to study the release kinetics of volatiles during eating and the possibility to consider volatile concentration similar to in vivo condition resulting to an improved characterization of the aroma profile.
    Screening for new sources of resistance to Clavibacter michiganensis subsp. michiganensis (Cmm) in tomato
    Sen, Y. ; Zhu, F. ; Vandenbroucke, H. ; Wolf, J.M. van der; Visser, R.G.F. ; Heusden, A.W. van - \ 2013
    Euphytica 190 (2013)2. - ISSN 0014-2336 - p. 309 - 317.
    bacterial canker - corynebacterium-michiganense - lycopersicon-esculentum - ssp michiganensis - seeds - pcr - quantification - crosses
    Bacterial canker of tomato, caused by Clavibacter michiganensis subsp. michiganensis (Cmm), is considered the most serious bacterial threat, resulting in high damages in production areas. Worldwide, Cmm is subjected to quarantine regulations.There is no cultivar in market containing Cmm resistance genes. This project aimed to screen tomatoes or wild relatives of tomato for resistance to Cmm, to be used for starting breeding programs. We have screened 24 different wild accessions of tomato and found several new tolerant sources: Solanum pimpinellifolium GI.1554, S. parviflorum LA735 and S. parviflorum LA2072. We also confirmed the tolerance which was reported previously in S. peruvianum LA2157, S. peruvianum PI127829, S. peruvianum LA385, S. habrochaites LA407 and S. lycopersicum cv. IRAT L3. No immunity was found. Also accessions showing a low disease score still contained high titers of bacteria as determined by a dilution plating method, using tow selective media. These results were confirmed with a TaqMan real time PCR assay, which was developed to determine and quantify Cmm in planta
    Tsw gene-based resistance is triggered by a functional RNA silencing suppressor protein of the Tomato spotted wilt virus
    Ronde, D. de; Butterbach, P.B.E. ; Lohuis, H. ; Hedil, M. ; Lent, J.W.M. van; Kormelink, R.J.M. - \ 2013
    Molecular Plant Pathology 14 (2013)4. - ISSN 1464-6722 - p. 405 - 415.
    mediated plant transformation - capsicum-chinense - cell-death - disease-resistance - lycopersicon-esculentum - viral suppressors - sw-5 gene - potato - tospovirus - agrobacterium
    As a result of contradictory reports, the avirulence (Avr) determinant that triggers Tsw gene-based resistance in Capsicum annuum against the Tomato spotted wilt virus (TSWV) is still unresolved. Here, the N and NSs genes of resistance-inducing (RI) and resistance-breaking (RB) isolates were cloned and transiently expressed in resistant Capsicum plants to determine the identity of the Avr protein. It was shown that the NSsRI protein triggered a hypersensitive response (HR) in Tsw-containing Capsicum plants, but not in susceptible Capsicum, whereas no HR was discerned after expression of the NRI/RB protein, or when NSsRB was expressed. Although NSsRI was able to suppress the silencing of a functional green fluorescence protein (GFP) construct during Agrobacterium tumefaciens transient assays on Nicotiana benthamiana, NSsRB had lost this capacity. The observation that RB isolates suppressed local GFP silencing during an infection indicated a recovery of RNA silencing suppressor activity for the NSs protein or the presence of another RNA interference (RNAi) suppressor. The role of NSs as RNA silencing suppressor and Avr determinant is discussed in the light of a putative interplay between RNAi and the natural Tsw resistance gene
    Rapid tomato volatile profiling by using proton-transfer reaction mass spectrometry (PTS-MS)
    Farneti, B. ; Cristescu, S.M. ; Costa, G. ; Harren, F.J.M. ; Woltering, E.J. - \ 2012
    Journal of Food Science 77 (2012)5. - ISSN 0022-1147 - p. C551 - C559.
    electronic nose - lycopersicon-esculentum - quality attributes - organic-compounds - flavor compounds - aroma volatiles - kidney beans - shelf-life - cultivars - harvest
    The availability of rapid and accurate methods to assess fruit flavor is of utmost importance to support quality control especially in the breeding phase. Breeders need more information and analytical tools to facilitate selection for complex multigenic traits such as flavor quality. In this study, it is shown that proton-transfer reaction mass spectrometry (PTR-MS) is a suitable method to monitor at high sensitivity the emission of volatiles determining the tomato aromatic profile such as hexanal, hexenals, methanol, ethanol, and acetaldehyde. The volatiles emitted by 14 tomato varieties (at red stage) were analyzed by 2 solvent-free headspace methods: solid-phase microextraction/gas chromatography MS and PTR-MS. Multivariate statistics (principal component analysis and cluster analysis) of the PTR-MS results allow an unambiguous separation between varieties, especially with a clear fingerprinting separation between the different tomato types: round truss, cocktail, and cherry tomatoes. PTR-MS was also successfully used to monitor the changes in volatile profiles during postharvest ripening and storage.
    Prediction of sweet pepper (Capsicum annuum) flavour over different harvests
    Eggink, P.M. ; Maliepaard, C.A. ; Tikunov, Y.M. ; Haanstra, J.P.W. ; Pohu-Flament, L.M.M. ; Wit-Maljaars, S.C. de; Willeboordse-Vos, F. ; Bos, S. ; Benning-de Waard, C. ; Grauw-van Leeuwen, P.J. de; Freymark, G. ; Bovy, A.G. ; Visser, R.G.F. - \ 2012
    Euphytica 187 (2012)1. - ISSN 0014-2336 - p. 117 - 131.
    lycopersicon-esculentum - chemical-composition - volatile compounds - metabolomics - tomatoes
    To better understand and predict the complex multifactorial trait flavor, volatile and non-volatile components were measured in fresh sweet pepper (Capsicum annuum) fruits throughout the growing season in a diverse panel of 24 breeding lines, hybrids, several cultivated genotypes and one gene bank accession. Biochemical profiles were linked to individual flavor attributes, that were objectively quantified by a trained descriptive expert panel. We used a Random Forest regression approach for prediction of the flavor attributes within and between harvests. Predictions of texture related attributes (juiciness, toughness, crunchiness and stickiness of the skin) and sweetness were good (around 60–65 %in the analyses with the three harvests combined). The predictions of the attributes aroma intensity, sourness and fruity/apple were somewhat lower and more variable between harvests. (E)-2-hexen-1-ol, neopentane, p-menth-1-en-9-al, 3-hepten-2-one, (Z)-b-ocimene, (Z)-2-penten-1-ol, 1-methyl-1,4-cyclohexadiene, glucose, fructose and three unknown volatile compounds were identified as key-metabolites involved in the flavor differences between both genotypes and harvests. The complex nature of flavor is exemplified by the observed masking effect of fructose and other sugars on sourness and sourness related metabolites, like citrate. The knowledge obtained from the overall biochemical, sensory and prediction analyses forms a basis for targeted flavor improvement by breeding.
    Auxin-induced Fruit Set in Capsicum annuum L. Requires Downstream Gibberellin Biosynthesis
    Tiwari, A. ; Offringa, R. ; Heuvelink, E. - \ 2012
    Journal of Plant Growth Regulation 31 (2012)4. - ISSN 0721-7595 - p. 570 - 578.
    plant-growth regulators - pisum-sativum - sweet-pepper - lycopersicon-esculentum - unpollinated ovaries - tomato fruits - pod wall - parthenocarpy - arabidopsis - metabolism
    A hierarchical scheme for the central role of the plant hormones auxin and gibberellins in fruit set and development has been established for the model plants Arabidopsis and tomato. In the fruit crop Capsicum annuum, the importance of auxin as an early signal in fruit set has also been recognized; however, the effect of gibberellins and their interaction with auxin has not yet been studied. The aim of this study was to determine the role of gibberellin and the hierarchy between auxin and gibberellin. We applied gibberellin alone or in combination with auxin or with the gibberellin biosynthesis inhibitor paclobutrazol on stigmas of emasculated flowers. Gibberellin application enhanced fruit set, whereas application of paclobutrazol reduced fruit set. The effect of paclobutrazol treatment could be counteracted by coapplication of gibberellin but not by auxin. These results indicate that in C. annuum, like in Arabidopsis and tomato, auxin is the major inducer of fruit set that acts in part by inducing gibberellin biosynthesis. Interestingly, gibberellin does not significantly contribute to the final fruit size but seems to play an important role in preventing flower and fruit abscission, a major determinant of production loss in C. annuum. At the same time, gibberellin together with auxin seems to balance cell division and cell expansion during fruit growth.
    Structural homology in the Solanaceae: analysis of genomic regions in support of synteny studies in tomato, potato and pepper
    Peters, S.A. ; Bargsten, J.W. ; Szinay, D. ; Belt, J. van de; Visser, R.G.F. ; Bai, Y. ; Jong, H. de - \ 2012
    The Plant Journal 71 (2012)4. - ISSN 0960-7412 - p. 602 - 614.
    genetic-linkage map - chromosomal rearrangements - lycopersicon-esculentum - solanum-lycopersicoides - repetitive sequences - mammalian evolution - resistance - fish - recombination - organization
    We have analysed the structural homology in euchromatin regions of tomato, potato and pepper with special attention for the long arm of chromosome 2 (2L). Molecular organization and colinear junctions were delineated using multi-color BAC FISH analysis and comparative sequence alignment. We found large-scale rearrangements including inversions and segmental translocations that were not reported in previous comparative studies. Some of the structural rearrangements are specific for the tomato clade, and differentiate tomato from potato, pepper and other Solanaceous species. Although local gene vicinity is largely preserved, there are many small-scale synteny perturbations. Gene adjacency in the aligned segments was frequently disrupted for 47% of the ortholog pairs as a result of gene and LTR retrotransposon insertions, and occasionally by single gene inversions and translocations. Our data also suggests that long distance intra-chromosomal rearrangements and local gene rearrangements have evolved frequently during speciation in the Solanum genus, and that small changes are more prevalent than large-scale differences. The occurrence of sonata and harbinger transposable elements and other repeats near or at junction breaks is considered in the light of repeat-mediated rearrangements and a reconstruction scenario for an ancestral 2L topology is discussed.
    The tomato genome sequence provides insights into fleshy fruit evolution
    Sato, S. ; Tabata, S. ; Hirakawa, H. ; Klein Lankhorst, R.M. ; Jong, H. de; Ham, R.C.H.J. van; Datema, E. ; Smit, S. ; Schijlen, E.G.W.M. ; Haarst, J.C. van; Peters, S.A. ; Henkens, M.H.C. ; Staveren, M.J. van; Mooijman, P.J.W. ; Hesselink, T. ; Belt, J. van de; Szinay, D. ; Bai, Y. ; Visser, R.G.F. - \ 2012
    Nature 485 (2012). - ISSN 0028-0836 - p. 635 - 641.
    lycopersicon-esculentum - gene - diversification - arabidopsis - patterns - ortholog - history - sorghum - potato
    Tomato (Solanum lycopersicum) is a major crop plant and a model system for fruit development. Solanum is one of the largest angiosperm genera1 and includes annual and perennial plants from diverse habitats. Here we present a high-quality genome sequence of domesticated tomato, a draft sequence of its closest wild relative, Solanum pimpinellifolium2, and compare them to each other and to the potato genome (Solanum tuberosum). The two tomato genomes show only 0.6% nucleotide divergence and signs of recent admixture, but show more than 8% divergence from potato, with nine large and several smaller inversions. In contrast to Arabidopsis, but similar to soybean, tomato and potato small RNAs map predominantly to gene-rich chromosomal regions, including gene promoters. The Solanum lineage has experienced two consecutive genome triplications: one that is ancient and shared with rosids, and a more recent one. These triplications set the stage for the neofunctionalization of genes controlling fruit characteristics, such as colour and fleshiness.
    Crop to wild introgression in lettuce: following the fate of crop genome segments in backcross populations
    Uwimana, B. ; Smulders, M.J.M. ; Hooftman, D.A.P. ; Hartman, Y. ; Tienderen, P.H. van; Jansen, J. ; McHale, L.K. ; Michelmore, R. ; Visser, R.G.F. ; Wiel, C.C.M. van de - \ 2012
    BMC Plant Biology 12 (2012). - ISSN 1471-2229
    quantitative trait loci - genetically-engineered organisms - gene flow - qtl analysis - lycopersicon-esculentum - domestication traits - helianthus-paradoxus - sunflower hybrids - field conditions - mixed models
    After crop-wild hybridization, some of the crop genomic segments may become established in wild populations through selfing of the hybrids or through backcrosses to the wild parent. This constitutes a possible route through which crop (trans)genes could become established in natural populations. The likelihood of introgression of transgenes will not only be determined by fitness effects from the transgene itself but also by the crop genes linked to it. Although lettuce is generally regarded as self-pollinating, outbreeding does occur at a low frequency. Backcrossing to wild lettuce is a likely pathway to introgression along with selfing, due to the high frequency of wild individuals relative to the rarely occurring crop-wild hybrids. To test the effect of backcrossing on the vigour of inter-specific hybrids, Lactuca serriola, the closest wild relative of cultivated lettuce, was crossed with L. sativa and the F1 hybrid was backcrossed to L. serriola to generate BC1 and BC2 populations. Experiments were conducted on progeny from selfed plants of the backcrossing families (BC1S1 and BC2S1). Plant vigour of these two backcrossing populations was determined in the greenhouse under non-stress and abiotic stress conditions (salinity, drought, and nutrient deficiency). Results Despite the decreasing contribution of crop genomic blocks in the backcross populations, the BC1S1 and BC2S1 hybrids were characterized by a substantial genetic variation under both non-stress and stress conditions. Hybrids were identified that performed equally or better than the wild genotypes, indicating that two backcrossing events did not eliminate the effect of the crop genomic segments that contributed to the vigour of the BC1 and BC2 hybrids. QTLs for plant vigour under non-stress and the various stress conditions were detected in the two populations with positive as well as negative effects from the crop. Conclusion As it was shown that the crop contributed QTLs with either a positive or a negative effect on plant vigour, we hypothesize that genomic regions exist where transgenes could preferentially be located in order to mitigate their persistence in natural populations through genetic hitchhiking.
    Penalized regression techniques for modeling relationships between metabolites and tomato taste attributes
    Menendez, P. ; Eilers, P. ; Tikunov, Y.M. ; Bovy, A.G. ; Eeuwijk, F. van - \ 2012
    Euphytica 183 (2012)3. - ISSN 0014-2336 - p. 379 - 387.
    lycopersicon-esculentum - nonvolatile components - organoleptic quality - selection - flavor - volatiles - lasso - identification - cultivars - traits
    The search for models which link tomato taste attributes to their metabolic profiling, is a main challenge within the breeding programs that aim to enhance tomato flavor. In this paper, we compared such models calculated by the traditional statistical approach, stepwise regression, with models obtained by the new generation of regression techniques, known as penalized regression or regularization methods. In addition, for penalized regression, different scenarios and various model selection criteria were discussed to conclude that classical crossvalidation, selects models with many superfluous variables whereas model selection criteria such as Bayesian information criterion, seem to be more suitable, when the goal is to find parsimonious models, to explain tomato taste attributes based on metabolic information. An exhaustive comparison of the discussed methodology was done for six sensory traits, showing that the most important covariates were identified by the stepwise regression as well as by some of the penalized regression methods, despite the general disagreement on the size of the regression coefficients between them. In particular, for stepwise regression the coefficients are inflated due to their high variance which is not the case with penalized regression, showing that this new methodology, can be an alternative to obtain more accurate models.
    GLYCOALKALOID METABOLISM1 Is Required for Steroidal Alkaloid Glycosylation and Prevention of Phytotoxicity
    Itkin, M. ; Rogachev, I. ; Alkan, N. ; Rosenberg, T. ; Malitsky, S. ; Masini, L. ; Meir, S. ; Lijima, Y. ; Aoki, K. ; Vos, R.C.H. de; Prusky, D. ; Beekwilder, M.J. ; Aharoni, A. - \ 2011
    The Plant Cell 23 (2011)12. - ISSN 1040-4651 - p. 4507 - 4525.
    campestris pv. vesicatoria - induced membrane disruption - alpha-tomatine - saponin biosynthesis - lycopersicon-esculentum - solanum-tuberosum - mass-spectrometry - gene-expression - plant - fruit
    Steroidal alkaloids (SAs) are triterpene-derived specialized metabolites found in members of the Solanaceae family that provide plants with a chemical barrier against a broad range of pathogens. Their biosynthesis involves the action of glycosyltransferases to form steroidal glycoalkaloids (SGAs). To elucidate the metabolism of SGAs in the Solanaceae family, we examined the tomato (Solanum lycopersicum) GLYCOALKALOID METABOLISM1 (GAME1) gene. Our findings imply that GAME1 is a galactosyltransferase, largely performing glycosylation of the aglycone tomatidine, resulting in SGA production in green tissues. Downregulation of GAME1 resulted in an almost 50% reduction in a-tomatine levels (the major SGA in tomato) and a large increase in its precursors (i.e., tomatidenol and tomatidine). Surprisingly, GAME1-silenced plants displayed growth retardation and severe morphological phenotypes that we suggest occur as a result of altered membrane sterol levels caused by the accumulation of the aglycone tomatidine. Together, these findings highlight the role of GAME1 in the glycosylation of SAs and in reducing the toxicity of SA metabolites to the plant cell.
    Identification of Genes in the Phenylalanine Metabolic Pathway by Ectopic Expression of a MYB Transcription Factor in Tomato Fruit
    Cin, V. Dal; Tieman, D.M. ; Tohge, T. ; McQuinn, R. ; Vos, C.H.R. de; Osorio, S. ; Schmelz, E.A. ; Taylor, M.G. ; Smits-Kroon, M.T. ; Schuurink, R.C. ; Haring, M.A. ; Giovannoni, J. ; Fernie, A.R. ; Klee, H.J. - \ 2011
    The Plant Cell 23 (2011)7. - ISSN 1040-4651 - p. 2738 - 2753.
    chromatography-mass spectrometry - prephenate aminotransferase - amino-acids - lycopersicon-esculentum - arabidopsis-thaliana - escherichia-coli - microarray data - cell-cultures - biosynthesis - arogenate
    Altering expression of transcription factors can be an effective means to coordinately modulate entire metabolic pathways in plants. It can also provide useful information concerning the identities of genes that constitute metabolic networks. Here, we used ectopic expression of a MYB transcription factor, Petunia hybrida ODORANT1, to alter Phe and phenylpropanoid metabolism in tomato (Solanum lycopersicum) fruits. Despite the importance of Phe and phenylpropanoids to plant and human health, the pathway for Phe synthesis has not been unambiguously determined. Microarray analysis of ripening fruits from transgenic and control plants permitted identification of a suite of coregulated genes involved in synthesis and further metabolism of Phe. The pattern of coregulated gene expression facilitated discovery of the tomato gene encoding prephenate aminotransferase, which converts prephenate to arogenate. The expression and biochemical data establish an arogenate pathway for Phe synthesis in tomato fruits. Metabolic profiling and 13C flux analysis of ripe fruits further revealed large increases in the levels of a specific subset of phenylpropanoid compounds. However, while increased levels of these human nutrition-related phenylpropanoids may be desirable, there were no increases in levels of Phe-derived flavor volatiles.
    Diversity between and within farmers’ varieties of tomato from Eritrea
    Asgedom, S. ; Vosman, B. ; Esselink, D. ; Struik, P.C. - \ 2011
    African journal of biotechnology 10 (2011)12. - ISSN 1684-5315 - p. 2193 - 2200.
    simple sequence repeat - ssr-markers - lycopersicon-esculentum - genetic-variation - polymorphic dna - identification - regions - plants - aflp - l.
    Tomato yields in Eritrea are low (15 Mg/ha) compared with 19 Mg/ha in Africa and 27 Mg/ha worldwide. This is partly caused by poor quality of varieties used. This study analysed the diversity among and heterogeneity within farmers’ varieties of tomato from Eritrea and compared these varieties with other African and Italian varieties. Fifteen simple sequence repeat (SSR) markers were used for the genetic analysis. Genetic similarities among the varieties were calculated and an Unweighted Pair Group Method with Arithmetic Mean analysis was performed. Furthermore, individual plants of varieties were genotyped to evaluate uniformity within varieties. A high degree of diversity was observed among the Eritrean varieties. Thirteen out of the 15 SSRs were polymorphic, with 2 to 5 alleles per marker. The dendrogram showed two major types of varieties: San-Marzano and Marglob. Eritrean varieties were closely related to old Italian varieties in both types. Analysis of the within-variety variation showed that the Eritrean tomato genotypes were less uniform than the other varieties, probably because of deliberate mixing. A survey among farmers showed that some of them purposely mixed seeds to prolong the harvesting period, for yield stability and stress tolerance. Farmers value ‘new material’ as a source of influx
    Seedling salt tolerance in tomato
    Junming Li, J. ; Liu, L. ; Bai, Y. ; Zhang, Pujuan ; Finkers, H.J. ; Du, Y. ; Visser, R.G.F. ; Heusden, A.W. van - \ 2011
    Euphytica 178 (2011)3. - ISSN 0014-2336 - p. 403 - 414.
    quantitative trait loci - introgression line population - lycopersicon-esculentum - vegetative growth - cultivated tomato - bacterial canker - qtl analysis - fruit yield - germination - salinity
    Soils with higher concentrations of salt are becoming more and more a constraint for many crops to obtain high yields. Wild tomato species, adapted to adverse environments, are a potential reservoir for genes underlying quantitative trait loci (QTL) related to salt tolerance in tomato. In this study two introgression line (IL) libraries derived from two different wild species, Solanum pennellii LA716 and Solanum lycopersicoides LA2951, were used to identify QTLs for salt tolerance in the seedling stage. In the S. pennellii IL library, four major QTLs were identified on chromosomes 6, 7 and 11. In the S. lycopersicoides IL library, six major QTLs were discovered which are located on chromosomes 4, 6, 9 and 12. Co-localization of QTLs on chromosome 6 in the two IL libraries and previously reports hinted that this locus might be conserved in the tomato crop. Three S. pennellii ILs (IL6-2, IL7-1 and IL7-5) harboring QTLs on chromosome 6 and 7 were crossed. Semi-dominance and dominance were shown for these three QTLs, and non-additive and epistatic interactions between them were observed
    Transcriptome and Metabolite Profiling Show That APETALA2a Is a Major Regulator of Tomato Fruit Ripening
    Karlova, R.B. ; Rosin, F.M.A. ; Busscher-Lange, J. ; Parapunova, V.A. ; Do, P.T. ; Fernie, A.R. ; Fraser, P.D. ; Baxter, C. ; Angenent, G.C. ; Maagd, R.A. de - \ 2011
    The Plant Cell 23 (2011)3. - ISSN 1040-4651 - p. 923 - 941.
    homeotic gene apetala2 - ethylene biosynthesis - flower development - 1-aminocyclopropane-1-carboxylate synthase - chromoplast differentiation - lycopersicon-esculentum - expression analysis - arabidopsis flower - seed development - organ identity
    Fruit ripening in tomato (Solanum lycopersicum) requires the coordination of both developmental cues as well as the plant hormone ethylene. Although the role of ethylene in mediating climacteric ripening has been established, knowledge regarding the developmental regulators that modulate the involvement of ethylene in tomato fruit ripening is still lacking. Here, we show that the tomato APETALA2a (AP2a) transcription factor regulates fruit ripening via regulation of ethylene biosynthesis and signaling. RNA interference (RNAi)-mediated repression of AP2a resulted in alterations in fruit shape, orange ripe fruits, and altered carotenoid accumulation. Microarray expression analyses of the ripe AP2 RNAi fruits showed altered expression of genes involved in various metabolic pathways, such as the phenylpropanoid and carotenoid pathways, as well as in hormone synthesis and perception. Genes involved in chromoplast differentiation and other ripening-associated processes were also differentially expressed, but softening and ethylene biosynthesis occurred in the transgenic plants. Ripening regulators RIPENING-INHIBITOR, NON-RIPENING, and COLORLESS NON-RIPENING (CNR) function upstream of AP2a and positively regulate its expression. In the pericarp of AP2 RNAi fruits, mRNA levels of CNR were elevated, indicating that AP2a and CNR are part of a negative feedback loop in the regulation of ripening. Moreover, we demonstrated that CNR binds to the promoter of AP2a in vitro
    Genome composition of 'Elatior'-begonias hybrids analyzed by genomic in situ hybridisation
    Marasek Ciolakowska, A.R. ; Ramanna, M.S. ; Laak, W.A. ; Tuyl, J.M. van - \ 2010
    Euphytica 171 (2010)2. - ISSN 0014-2336 - p. 273 - 282.
    hordeum-vulgare-l - lycopersicon-esculentum - chromosome elimination - cytogenetic analysis - bulbosum l - plant dna - differentiation - extraction - nicotiana - progenies
    Interspecific hybridization of various tuberous Begonia species hybrids with Begonia socotrana results in so-called 'Elatior'-begonias hybrids (B. x hiemalis Fotsch). In our study, genomic in situ hybridization (GISH) has been employed to assess the genome composition in eleven 'Elatior'-begonias hybrids and their ancestor genotypes. Genomic DNA of tuberous Begonia was sonicated to 1-10-kb fragments, labelled by nick translation with digoxigenin-11-dUTP and used as a probe whereas B. socotrana DNA was autoclaved to 100 bp fragments and used as block. The genome of tuberous Begonia was clearly pronounced in 'Elatior'-begonias when the probe concentration was similar to 3.75 ng/mu l (150 ng/slide), with 30 times the excess of B. socotrana blocking DNA and stringency of post hybridization washings at 73% (0.1x SSC at 42A degrees C). In 'Elatior'-begonias hybrids GISH distinguished two groups comprising short (0.6-1.03 mu m in length) and relatively longer chromosomes (1.87-3.88 mu m) which represent B. socotrana and tuberous Begonia genomes, respectively. The number of chromosomes derived from tuberous Begonia ranged from 14 to 56 and for B. socotrana from 7 to 28 which suggest the presence of different ploidy levels in analyzed 'Elatior'-begonia hybrids. Intergenomic recombination has not been detected through GISH in hybrids analyzed. Genomic in situ hybridization turned out to be useful to identify the genome constitution of 'Elatior'-begonia hybrids and thus gain an insight into the origins of these cultivars. This knowledge on the ploidy level and genome composition is essential for further progress in breeding Begonias.
    Development of a locus-specific, co-dominant SCAR marker for assisted-selection of the Sw-5 (Tospovirus resistance) gene cluster in a wide range of tomato accessions
    Dianese, E.C. ; Fonseca, M.E.N. ; Goldbach, R.W. ; Kormelink, R.J.M. ; Inoue-Nagata, A.K. ; Resende, R.O. de; Boiteux, L.S. - \ 2010
    Molecular Breeding 25 (2010)1. - ISSN 1380-3743 - p. 133 - 142.
    spotted-wilt-virus - lycopersicon-esculentum - thrips transmission - tswv resistance - rapd markers - peruvianum - sw5
    The best levels of broad-spectrum Tospovirus resistance reported in tomatoes thus far are conferred by the Sw-5 locus. This locus contains at least five paralogues (denoted Sw-5a through Sw-5e), of which Sw-5b represents the actual resistance gene. Here we evaluated a panel of seven PCR primer pairs matching different sequences within a genomic region spanning the Sw-5a and Sw-5b gene cluster. Primer efficiency evaluation was done employing tomato isolines with and without the Sw-5 locus. One primer pair produced a single and co-dominant polymorphism between susceptible and resistant isolines. Sequence analysis of these amplicons indicated that they were specific for the Sw-5 locus and their differences were due to insertions/deletions. The polymorphic SCAR amplicon encompass a conserved sequence of the promoter region of the functional Sw-5b gene, being located in the position -31 from its open reading frame. This primer pair was also evaluated in field assays and with a collection of accessions known to be either susceptible or resistant to tospoviruses. An almost complete correlation was found between resistance under greenhouse/field conditions and the presence of the marker. Therefore, this primer pair is a very useful tool in marker-assisted selection systems in a large range of tomato accessions.
    Differences in N uptake and fruit quality between organically and conventionally grown greenhouse tomatoes
    Gravel, V. ; Blok, W.J. ; Hallmann, E. ; Carmona-Torres, C. ; Wang, H. ; Peppel, A.C. van de; Condor Golec, A.F. ; Dorais, M. ; Meeteren, U. van; Heuvelink, E. ; Rembialkowska, E. ; Bruggen, A.H.C. van - \ 2010
    Agronomy for Sustainable Development 30 (2010)4. - ISSN 1774-0746 - p. 797 - 806.
    biologische landbouw - stikstof - tomaten - kwaliteit - vruchtgroenten - bemesting - glasgroenten - organic farming - nitrogen - tomatoes - quality - fruit vegetables - fertilizer application - greenhouse vegetables - nutritional-value - lycopersicon-esculentum - plant foods - soil - yield - fertilization - extraction - flavonoids - vegetables
    Soil-bound intensive greenhouse production has been scrutinized for its sustainability due to contamination of ground water by over-fertilization resulting in leaching of nutrients. As environmental guidelines are becoming more restrictive worldwide, and especially in Europe, many greenhouse growers have converted to more sustainable production systems including rockwool culture with recycled water and organic cropping systems in soil. The increase in popularity of organic production systems has amplified the debate whether organically grown produce is healthier than conventional produce. So far, little is known about the variations in fruit quality associated with production systems for greenhouse grown tomatoes. Thus, two organic (organic fertilization with and without straw amendment) and three conventional tomato cropping systems (regular and increased nutrient solution in rockwool and regular fertilization in soil) were compared in order to evaluate differences in nutrient availability and effects on fruit quality over a three-year period. Three modern medium-sized round tomato cultivars and one old cultivar were compared. There were no significant interactions between cropping systems and cultivars, so that main effects of systems and cultivars could be evaluated. Fruit yields in the organic systems were similar to those obtained in the conventional soil-bound system, but 15% lower than in the regular rockwool system, even though nitrogen concentrations in soil were not limiting in any of the production systems. Frequent organic amendments resulted in higher soil contents in the organic system without straw than in the other soil-bound systems, indicating that the organic systems were not yet stable in terms of nutrient availability after three years. A fruit quality index, based on the contents of compounds such as lycopene, ß-carotene and vitamin C, was similar in all cropping systems. The old cultivar had a significantly higher quality index, but a lower yield than the other cultivars. According to this study, high quality tomatoes can be obtained through proper adjustment of the quantity and the source of nitrogen fertilizers in organic and conventional cropping systems and the use of selected cultivars with a high nutrient use efficiency for organic systems.
    FISH applications for genomics and plant breeding strategies in tomato and other Solanaceous crops
    Szinay, D. ; Bai, Y. ; Visser, R.G.F. ; Jong, J.H. de - \ 2010
    Cytogenetic and Genome Research 129 (2010)1-3. - ISSN 1424-8581 - p. 199 - 210.
    in-situ hybridization - high-resolution fish - extended dna fibers - lycopersicon-esculentum - recombination nodules - heterochromatic genes - chromosome identification - synaptonemal complexes - pachytene chromosomes - sequence-analysis
    This paper describes the use of advanced fluorescence in situ hybridization (FISH) technologies for genomics and breeding of tomato and related Solanum species. The first part deals with the major determinants of FISH technology: (1) spatial resolution, which depends on the diffraction limit of the microscope and the type of chromosome, chromatin or isolated DNA fibres as target for the hybridisation; (2) the detection sensitivity, which is limited by the sensitivity and dynamic range of the CCD camera and the quality of the microscope, and the amplification system of the weak signals from tiny probe molecules; (3) simultaneous detection of multiple probes labelled directly or indirectly with up to 5 different fluorophores, whether or not in different combinations and/or mixed at different ratios. The power and usability of such multicolour FISH is indispensable when large numbers of bacterial artificial chromosomes (BACs) or other vectors with genomic DNA are available. Mapping of multiple BACs on chromosomes are powerful instruments confirming their assumed genetic position, whereas pooled BACs for a given chromosome arm will reveal the gaps between the BACs or derived contigs of their physical maps. Tandem and dispersed repeats, which are abundant in the genomes of most species, can be analysed in repeat bar coding FISH, showing the major blocks of repeats in heterochromatin and euchromatin areas. Repeat-rich areas of the chromosomes can also be demonstrated by hybridisation of probed Cot fractions of sheared genomic DNA; a powerful method to elucidate the heterochromatin domains for genomic studies. In addition, unlabelled Cot DNA, as blocking agent in BAC-FISH painting, suppresses repetitive sequences from the BACs to hybridise on the chromosomes. Cross-species BAC-FISH painting with labelled probes from tomato and potato BACs and hybridised on the chromosomes of related species, under appropriate conditions, is a powerful instrument to demonstrate chromosomal rearrangements, including inversions and translocations. The technology not only supports phylogenetic studies between the taxa under study but can also be helpful in breeding programs with crops containing introgressed regions from related species when linkage drag or meiotic pairing disturbances between the homoeologues are assumed. In the next steps in comparative genomics, we now can detect smaller chromosomal and DNA rearrangements, diminutions and amplifications of repeats and changes of the epigenetic status of introgressed regions
    Emerging Viral Diseases of Tomato Crops
    Hanssen, I.M. ; Lapidot, M. ; Thomma, B.P.H.J. - \ 2010
    Molecular Plant-Microbe Interactions 23 (2010)5. - ISSN 0894-0282 - p. 539 - 548.
    pepino-mosaic-virus - leaf-curl-virus - infectious-chlorosis-virus - zonate spot virus - complete nucleotide-sequence - picorna-like virus - torrado-virus - 1st report - plant-viruses - lycopersicon-esculentum
    Viral diseases are an important limiting factor in many crop production systems. Because antiviral products are not available, control strategies rely on genetic resistance or hygienic measures to prevent viral diseases, or on eradication of diseased crops to control such diseases. Increasing international travel and trade of plant materials enhances the risk of introducing new viruses and their vectors into production systems. In addition, changing climate conditions can contribute to a successful spread of newly introduced viruses or their vectors and establishment of these organisms in areas that were previously unfavorable. Tomato is economically the most important vegetable crop worldwide and many viruses infecting tomato have been described, while new viral diseases keep emerging. Pepino mosaic virus is a rapidly emerging virus which has established itself as one of the most important viral diseases in tomato production worldwide over recent years. Begomovirus species and other whitefly-transmitted viruses are invading into new areas, and several recently described new viruses such as Tomato torrado virus and new Tospovirus species are rapidly spreading over large geographic areas. In this article, emerging viruses of tomato crops are discussed.
    A role for differential glycoconjugation in the emission of phenylpropanoid volatiles from tomato fruit discovered using a metabolic data fusion approach.
    Tikunov, Y.M. ; Vos, C.H. de; Gonzalez Paramas, A.M. ; Hall, R.D. ; Bovy, A.G. - \ 2010
    Plant Physiology 152 (2010). - ISSN 0032-0889 - p. 55 - 70.
    methyl salicylate - lycopersicon-esculentum - bahd acyltransferase - solanum-lycopersicon - clitoria-ternatea - aroma components - flavor compounds - plant volatiles - glycosides - identification
    A role for differential glycoconjugation in the emission of phenylpropanoid volatiles from ripening tomato fruit (Solanum lycopersicum) upon fruit tissue disruption has been discovered in this study. Application of a multiinstrumental analytical platform for metabolic profiling of fruits from a diverse collection of tomato cultivars revealed that emission of three discriminatory phenylpropanoid volatiles, namely methyl salicylate, guaiacol, and eugenol, took place upon disruption of fruit tissue through cleavage of the corresponding glycoconjugates, identified putatively as hexose-pentosides. However, in certain genotypes, phenylpropanoid volatile emission was arrested due to the corresponding hexose-pentoside precursors having been converted into glycoconjugate species of a higher complexity: dihexose-pentosides and malonyl-dihexose-pentosides. This glycoside conversion was established to occur in tomato fruit during the later phases of fruit ripening and has consequently led to the inability of red fruits of these genotypes to emit key phenylpropanoid volatiles upon fruit tissue disruption. This principle of volatile emission regulation can pave the way to new strategies for controlling tomato fruit flavor and taste.
    Rpi-vnt1.1, a Tm-2(2) Homolog from Solanum venturii, Confers Resistance to Potato Late Blight
    Foster, S.J. ; Park, T.H. ; Pel, M. ; Brigneti, G. ; Sliwka, J. ; Jagger, L. ; Vossen, E.A.G. van der; Jones, J.D.G. - \ 2009
    Molecular Plant-Microbe Interactions 22 (2009)5. - ISSN 0894-0282 - p. 589 - 600.
    broad-spectrum resistance - race-specific resistance - phytophthora-infestans mont - disease-resistance - chromosome-ix - lycopersicon-esculentum - r-gene - hypersensitive resistance - united-states - aflp markers
    Despite the efforts of breeders and the extensive use of fungicide control measures, late blight still remains a major threat to potato cultivation worldwide. The introduction of genetic resistance into cultivated potato is considered a valuable method to achieve durable resistance to late blight. Here, we report the identification and cloning of Rpi-vnt1.1, a previously uncharacterized late-blight resistance gene from Solanum venturii. The gene was identified by a classical genetic and physical mapping approach and encodes a coiled-coil nucleotide-binding leucine-rich repeat protein with high similarity to Tm-22 from S. lycopersicum which confers resistance against Tomato mosaic virus. Transgenic potato and tomato plants carrying Rpi-vnt1.1 were shown to be resistant to Phytophthora infestans. Of 11 P. infestans isolates tested, only isolate EC1 from Ecuador was able to overcome Rpi-vnt1.1 and cause disease on the inoculated plants. Alleles of Rpi-vnt1.1 (Rpi-vnt1.2 and Rpivnt1.3) that differed by only a few nucleotides were found in other late-blight-resistant accessions of S. venturii. The late blight resistance gene Rpi-phu1 from S. phureja is shown here to be identical to Rpi-vnt1.1, suggesting either that this strong resistance gene has been maintained since a common ancestor, due to selection pressure for blight resistance, or that genetic exchange between S. venturii and S. phureja has occurred at some time.
    C22 Isomerization in a-Tomatine-to-Esculeoside A Conversion during Tomato Ripening Is Driven by C27 Hydroxylation of Triterpenoidal Sekeleton
    Yamanaka, T. ; Vincken, J.P. ; Zuilhof, H. ; Legger, A. ; Takada, N. ; Gruppen, H. - \ 2009
    Journal of Agricultural and Food Chemistry 57 (2009)9. - ISSN 0021-8561 - p. 3786 - 3791.
    steroidal alkaloid glycosides - pulsed amperometric detection - lycopersicon-esculentum - fruits - plant - dehydrotomatine - glycoalkaloids - performance - maturation - hplc
    Compositional analysis by liquid chromatography/mass spectrometry of triterpenoid glycosides in different tomato cultivars, ripening stages, and parts of fruits showed that alpha-tomatine was generally most abundant in the flesh of the mature green stage, whereas esculeoside A was predominant in that of the red ripe stage. The sum of these glycoalkaloids was more or less constant, suggesting that alpha-tomatine is converted to esculeoside A during ripening. Besides various substitutions, the C22alphaN -> C22ßN isomerization is an important step in this transformation. By quantum chemical calculations it was shown that hydroxylation at C27 of the triterpenoidal skeleton is the driving force behind the isomerization. For the protonated form of the glycoalkaloid (predominant at the pH of tomato tissue), the C22ßN configuration becomes more favorable than that of C22alphaN, through the extra energy provided by the hydrogen bond between the protonated nitrogen and the lone pair of the oxygen of the C27-OH
    Mapping and Cloning of Late Blight Resistance Genes from Solanum venturii Using an Interspecific Candidate Gene Approach
    Pel, M. ; Foster, S.J. ; Park, T.H. ; Rietman, H. ; Arkel, G. van; Jones, J.D.G. ; Eck, H.J. van; Jacobsen, E. ; Visser, R.G.F. ; Vossen, E.A.G. van der - \ 2009
    Molecular Plant-Microbe Interactions 22 (2009)5. - ISSN 0894-0282 - p. 601 - 615.
    quantitative trait locus - race-specific resistance - nbs-lrr proteins - phytophthora-infestans - disease-resistance - r-gene - nucleotide-binding - field-resistance - lycopersicon-esculentum - nicotiana-benthamiana
    Late blight, caused by the oomycete Phytophthora infestans, is one of the most devastating diseases of potato. Resistance (R) genes from the wild species Solanum demissum have been used by breeders to generate late-blight-resistant cultivars but resistance was soon overcome by the pathogen. A more recent screening of a large number of wild species has led to the identification of novel sources of resistance, many of which are currently being characterized further. Here, we report on the cloning of dominant Rpi genes from S. venturii. Rpi-vnt1.1 and Rpi-vnt1.3 were mapped to chromosome 9 using nucleotide binding site (NBS) profiling. Subsequently, a Tm-22-based allele mining strategy was used to clone both genes. Rpi-vnt1.1 and Rpi-vnt1.3 belong to the coiled-coil NBS leucine-rich repeat (LRR) class of plant R genes and encode predicted peptides of 891 and 905 amino acids (aa), respectively, which share 75% amino acid identity with the Tomato mosaic virus resistance protein Tm-22 from tomato. Compared with Rpi-vnt1.1, Rpi-vnt1.3 harbors a 14-aa insertion in the N-terminal region of the protein and two different amino acids in the LRR domain. Despite these differences, Rpi-vnt1.1 and Rpi-vnt1.3 genes have the same resistance spectrum
    Changes in gene and protein expression during tomato ripening - consequences for the safety assessment of new crop plant varieties
    Kok, E.J. ; Lehesranta, S.J. ; Dijk, J.P. van; Helsdingen, J.R. ; Dijksma, W.T.P. ; Hoef, A.M.A. van; Koistinen, K.M. ; Karenlampi, S.O. ; Kuiper, H.A. ; Keijer, J. - \ 2008
    Food Science and Technology International 14 (2008)6. - ISSN 1082-0132 - p. 503 - 518.
    lycopersicon-esculentum - fruit maturation - transcriptome - translation - cloning
    An important part of the comparative approach to assess the safety of new crop plant varieties is an extensive compositional analysis, including the measurement of all key nutrients and antinutrients in a specific crop. The study described here investigates the applicability of `omics' technologies, transcriptomics and proteomics, as additional tools in this comparative safety assessment. The aim of the work was to assess the extent of the natural variation in ripening tomato fruits as a model crop and to determine whether it is possible to develop simple `ripening stage' criteria for the sampling of fruits for `omics' analyses. It is shown that the set-up of an `omics' study is of crucial importance. Samples under scrutiny should be well-matched with relation to environmental conditions during growth and harvest, including the stage of ripening, as is stipulated in international guidance documents for the nutritional and toxicological assessment of genetically modified plants
    Isolation, Characterization, and Surfactant Properties of the Major Triterpenoid Glycosides from Unripe Tomato Fruits
    Yamanaka, T. ; Vincken, J.P. ; Waard, P. de; Sanders, M.G. ; Takada, N. ; Gruppen, H. - \ 2008
    Journal of Agricultural and Food Chemistry 56 (2008)23. - ISSN 0021-8561 - p. 11432 - 11440.
    steroidal alkaloid glycosides - tandem mass-spectrometry - lycopersicon-esculentum - electrospray-ionization - liquid-chromatography - glycoalkaloids - saponins - plant - dehydrotomatine - soyasaponins
    Various triterpenoid glycosides were extracted from whole unripe tomato fruits (Lycopersicon esculentum cv. Cedrico), using aqueous 70% (v/v) ethanol to study their surfactant properties. Cation-exchange chromatography using a Source 15S column and subsequent semipreparative HPLC using an XTerra RP18 were employed to purify individual triterpenoid glycosides from the extract. The structure of the purified compounds was established by mass spectrometry and nuclear magnetic resonance spectroscopy. The furostanol glycoside tomatoside A (749 mg/kg of DW) and the glycoalkaloids ¿-tomatine (196 mg/kg of DW) and esculeoside A (427 mg/kg of DW) were the major triterpenoid glycosides present. Furthermore, minor amounts of a new dehydrofurostanol glycoside, dehydrotomatoside, were found. The critical micelle concentrations of the major triterpenoid glycosides, ¿-tomatine, tomatoside A, and esculeoside A, were determined as 0.099, 0.144, and 0.412 g/L, respectively. The results show that tomatoside A, and not the more well-known ¿-tomatine, is the predominant triterpenoidal surfactant in unripe tomato fruits.
    FISH mapping and molecular organization of the major repetitive sequences of tomato
    Chang, S.B. ; Yang, T.J. ; Datema, E. ; Vugt, J. van; Vosman, B. ; Kuipers, A. ; Meznikova, M. ; Szinay, D. ; Klein Lankhorst, R.M. ; Jacobsen, E. ; Jong, J.H.S.G.M. de - \ 2008
    Chromosome Research 16 (2008)7. - ISSN 0967-3849 - p. 919 - 933.
    in-situ hybridization - ty1-copia group retrotransposons - repeated dna-sequences - high-resolution fish - lycopersicon-esculentum - pachytene chromosomes - metaphase chromosomes - centromeric region - genome - genes
    This paper presents a bird's-eye view of the major repeats and chromatin types of tomato. Using fluorescence in-situ hybridization (FISH) with Cot-1, Cot-10 and Cot-100 DNA as probes we mapped repetitive sequences of different complexity on pachytene complements. Cot-100 was found to cover all heterochromatin regions, and could be used to identify repeat-rich clones in BAC filter hybridization. Next we established the chromosomal locations of the tandem and dispersed repeats with respect to euchromatin, nucleolar organizer regions (NORs), heterochromatin, and centromeres. The tomato genomic repeats TGRII and TGRIII appeared to be major components of the pericentromeres, whereas the newly discovered TGRIV repeat was found mainly in the structural centromeres. The highly methylated NOR of chromosome 2 is rich in [GACA](4), a microsatellite that also forms part of the pericentromeres, together with [GA](8), [GATA](4) and Ty1-copia. Based on the morphology of pachytene chromosomes and the distribution of repeats studied so far, we now propose six different chromatin classes for tomato: (1) euchromatin, (2) chromomeres, (3) distal heterochromatin and interstitial heterochromatic knobs, (4) pericentromere heterochromatin, (5) functional centromere heterochromatin and (6) nucleolar organizer region
    High-resolution chromosome mapping of BACs using multi-colour FISH and pooled-BAC FISH as a backbone for sequencing tomato chromosome 6
    Szinay, D. ; Chang, S.B. ; Khrustaleva, L.I. ; Peters, S.A. ; Schijlen, E.G.W.M. ; Bai, Y. ; Stiekema, W. ; Ham, R.C.H.J. van; Jong, H. de; Klein Lankhorst, R.M. - \ 2008
    The Plant Journal 56 (2008)4. - ISSN 0960-7412 - p. 627 - 637.
    molecular linkage maps - lycopersicon-esculentum - root-knot - genome sequence - pachytene chromosomes - metaphase chromosomes - arabidopsis-thaliana - meiotic pachytene - dna-sequences - rice genome
    Within the framework of the International Solanaceae Genome Project, the genome of tomato (Solanum lycopersicum) is currently being sequenced. We follow a 'BAC-by-BAC' approach that aims to deliver high-quality sequences of the euchromatin part of the tomato genome. BACs are selected from various libraries of the tomato genome on the basis of markers from the F2.2000 linkage map. Prior to sequencing, we validated the precise physical location of the selected BACs on the chromosomes by five-colour high-resolution fluorescent in situ hybridization (FISH) mapping. This paper describes the strategies and results of cytogenetic mapping for chromosome 6 using 75 seed BACs for FISH on pachytene complements. The cytogenetic map obtained showed discrepancies between the actual chromosomal positions of these BACs and their markers on the linkage group. These discrepancies were most notable in the pericentromere heterochromatin, thus confirming previously described suppression of cross-over recombination in that region. In a so called pooled-BAC FISH, we hybridized all seed BACs simultaneously and found a few large gaps in the euchromatin parts of the long arm that are still devoid of seed BACs and are too large for coverage by expanding BAC contigs. Combining FISH with pooled BACs and newly recruited seed BACs will thus aid in efficient targeting of novel seed BACs into these areas. Finally, we established the occurrence of repetitive DNA in heterochromatin/euchromatin borders by combining BAC FISH with hybridization of a labelled repetitive DNA fraction (Cot-100). This strategy provides an excellent means to establish the borders between euchromatin and heterochromatin in this chromosome.
    Map - vs. homology - based cloning for the recessive gene ol-2 conferring resistance to tomato powdery mildew
    Pavan, S.N.C. ; Zheng, Z. ; Borisova, M. ; Berg, P.M.M.M. van den; Lotti, C. ; Giovanni, C. de; Lindhout, P. ; Jong, J.H. de; Ricciardi, L. ; Visser, R.G.F. ; Bai, Y. - \ 2008
    Euphytica 162 (2008)1. - ISSN 0014-2336 - p. 91 - 98.
    oidium-neolycopersici - lycopersicon-esculentum - rflp analysis - markers - locus - aflp - heterochromatin - identification - defense - plants
    The recessive gene ol-2 confers papilla-associated and race-non-specific resistance to tomato powdery mildew caused by Oidium neolycopersici. In order to facilitate marker assisted selection (MAS) in practical breeding programmes, we identified two simple sequence repeat (SSR) markers and one cleaved amplified polymorphic sequence (CAPS) marker which are linked to the resistance locus and co-dominantly inherited. Aiming to provide a base for ol-2 positional cloning, we used a large segregating F2 population to merge these markers with all the ol-2 linked amplified fragment length polymorphism (AFLP®) markers previously identified in an integrated genetic map. By screening a tomato bacterial artificial chromosome (BAC) library, we detected two BAC clones containing two expressed sequence tags (ESTs) homologous to the gene mlo, responsible for powdery mildew resistance in barley, as well as an ol-2-linked marker. Chromosomal mapping by Fluorescence in situ Hybridization (FISH) revealed major signals of the two BAC DNAs in the pericentromeric heterochromatin of the short arm of chromosome 4, in the same region where the ol-2 gene was previously mapped. The genetic and cytogenetic co-localisation between ol-2 and tomato mlo-homologue(s), in addition to the similarity of ol-2 and mlo resistances for both genetic and phytopathological characteristics, suggests that ol-2 is likely a mlo-homologue. Thus, a homology-based cloning approach could be more suitable than positional cloning for ol-2 isolation.
    Diversity and linkage disequilibrium analysis wihtin a selected set of cultivated tomatoes
    Berloo, R. van; Zhu, A. ; Ursem, R.A. ; Verbakel, H. ; Gort, G. ; Eeuwijk, F.A. van - \ 2008
    Theoretical and Applied Genetics 117 (2008). - ISSN 0040-5752 - p. 89 - 101.
    fragment-length-polymorphism - lycopersicon-esculentum - genetic diversity - rapd markers - aflp markers - software - accessions - stability - inference - map
    Within the Dutch genomics initiative the ¿Centre for Biosystems Genomics¿ (CBSG) a major research effort is directed at the identification and unraveling of processes and mechanisms affecting fruit quality in tomato. The basis of this fruit quality program was a diverse set of 94 cultivated tomato cultivars, representing a wide spectrum of phenotypes for quality related traits. This paper describes a diversity study performed on these cultivars, using information of 882 AFLP markers, of which 304 markers had a known map position. The AFLP markers were scored as much as possible in a co-dominant fashion. We investigated genome distribution and coverage for the mapped markers and conclude that it proved difficult to arrive at a dense and uniformly distributed coverage of the genome with markers. Mapped markers and unmapped markers were used to investigate population structure. A clear substructure was observed which seemed to coincide with a grouping based on fruit size. Finally, we studied amount and decay of linkage disequilibrium (LD) along the chromosomes. LD was observed over considerable (genetic) distances. We discuss the feasibility of marker-trait association studies and conclude that the amount of genetic variation in our set of cultivars is limited, but that there exists scope for association studies
    Mapping and characterization of novel parthenocarpy QTLs in tomato
    Gorguet, B.J.M. ; Eggink, P.M. ; Ocaña, J. ; Tiwari, A. ; Schipper, E.H. ; Finkers, H.J. ; Visser, R.G.F. ; Heusden, A.W. van - \ 2008
    Theoretical and Applied Genetics 116 (2008)6. - ISSN 0040-5752 - p. 755 - 767.
    quantitative trait loci - lycopersicon-esculentum - botrytis-cinerea - resistance - hirsutum - set - auxin-response-factor8 - identification - introgression - chromosomes
    Parthenocarpy is the development of the fruit in absence of pollination and/or fertilization. In tomato, parthenocarpy is considered as an attractive trait to solve the problems of fruit setting under unfavorable conditions. We studied the genetics of parthenocarpy in two different lines, IL5-1 and IVT-line 1, both carrying Solanum habrochaites chromosome segments. Parthenocarpy in IL5-1 is under the control of two QTLs, one on chromosome 4 (pat4.1) and one on chromosome 5 (pat5.1). IVT-line 1 also contains two parthenocarpy QTLs, one on chromosome 4 (pat4.2) and one on chromosome 9 (pat9.1). In addition, we identified one stigma exsertion locus in IL5-1, located on the long arm of chromosome 5 (se5.1). It is likely that pat4.1, from IL5-1 and pat4.2, from IVT-line 1, both located near the centromere of chromosome 4 are allelic. By making use of the microsynteny between tomato and Arabidopsis in this genetic region, we identified ARF8 as a potential candidate gene for these two QTLs. ARF8 is known to act as an inhibitor for further carpel development in Arabidopsis, in absence of pollination/fertilization. Expression of an aberrant form of the Arabidopsis ARF8 gene, in tomato, has been found to cause parthenocarpy. This candidate gene approach may lead to the first isolation of a parthenocarpy gene in tomato and will allow further use in several crop species
    Breeding for a more energy efficient greenhouse tomato: past and future perspectives
    Ploeg, A. van der; Meer, M. van der; Heuvelink, E. - \ 2007
    Euphytica 158 (2007)1-2. - ISSN 0014-2336 - p. 129 - 138.
    lycopersicon-esculentum - growth - temperature - fruit - improvement - yield - cultivars - quality - biomass
    Energy efficiency can be increased either by increasing the production per m2 or by reducing the energy input per m2, e.g. by reducing temperature set-points in the greenhouse. So far, in Dutch glasshouse tomatoes energy efficiency was almost exclusively raised by yield increases. To study the role of tomato breeding in this production increase, yield and underlying components of 7 cultivars released between 1950 and 2002 were studied. Furthermore, variation in temperature response between cultivars was studied. In three experiments yield and biomass production of in total 11 cultivars were evaluated at two temperature regimes (17/15°C and 21/19°C day/night temperature set-points). Breeding has resulted in a remarkable increase in production. Under current conditions, yield of modern cultivars was on average 40% higher than yield of `Moneymaker¿, released in 1950. This increase in production resulted from a higher light use efficiency. Although the fraction of assimilates partitioned to the fruits showed small differences between cultivars, this trait was not related to year of release. Furthermore, more recently introduced cultivars produced larger fruits rather than more fruits. All cultivars responded similar to both temperature regimes for all important characteristics, limiting the possibilities of using existing cultivars in a breeding program for improved yield at lower temperatures.
    Domestication and breeding of tomatoes: what have we gained and what can we gain in the future?
    Bai, Y. ; Lindhout, P. - \ 2007
    Annals of Botany 100 (2007)5. - ISSN 0305-7364 - p. 1085 - 1094.
    quantitative trait loci - backcross qtl analysis - lycopersicon-esculentum - fruit size - cultivated tomato - solanum-lycopersicoides - genus lycopersicon - genetic diversity - natural variation - resistance genes
    Background It has been shown that a large variation is present and exploitable from wild Solanum species but most of it is still untapped. Considering the thousands of Solanum accessions in different gene banks and probably even more that are still untouched in the Andes, it is a challenge to exploit the diversity of tomato. What have we gained from tomato domestication and breeding and what can we gain in the future? Scope This review summarizes progress on tomato domestication and breeding and current efforts in tomato genome research. Also, it points out potential challenges in exploiting tomato biodiversity and depicts future perspectives in tomato breeding with the emerging knowledge from tomato-omics. Conclusions From first domestication to modern breeding, the tomato has been continually subjected to human selection for a wide array of applications in both science and commerce. Current efforts in tomato breeding are focused on discovering and exploiting genes for the most important traits in tomato germplasm. In the future, breeders will design cultivars by a process named 'breeding by design' based on the combination of science and technologies from the genomic era as well as their practical skills.
    Three QTLs for Botrytis cinerea resistance in tomato
    Finkers, H.J. ; Berg, P.M.M.M. van den; Berloo, R. van; Have, A. ten; Heusden, A.W. van; Kan, J.A.L. van; Lindhout, P. - \ 2007
    Theoretical and Applied Genetics 114 (2007)4. - ISSN 0040-5752 - p. 585 - 593.
    recombinant inbred lines - lycopersicon-esculentum - linkage maps - backcross - hirsutum - phytoalexins - fungal - plants - aflp - populations
    Tomato (Solanum lycopersicum) is susceptible to grey mold (Botrytis cinerea). Partial resistance to this fungus was identified in accessions of wild relatives of tomato such as S. habrochaites LYC4. In order to identify loci involved in quantitative resistance (QTLs) to B. cinerea, a population of 174 F2 plants was made originating from a cross between S. lycopersicum cv. Moneymaker and S. habrochaites LYC4. The population was genotyped and tested for susceptibility to grey mold using a stem bioassay. Rbcq1, a QTL reducing lesion growth (LG) and Rbcq2, a QTL reducing disease incidence (DI) were identified. Rbcq1 is located on Chromosome 1 and explained 12% of the total phenotypic variation while Rbcq2 is located on Chromosome 2 and explained 15% of the total phenotypic variation. Both QTL effects were confirmed by assessing disease resistance in two BC2S1 progenies segregating for either of the two QTLs. One additional QTL, Rbcq4 on Chromosome 4 reducing DI, was identified in one of the BC2S1 progenies. F2 individuals, homozygous for the Rbcq2 and Rbcq4 alleles of S. habrochaites showed a reduction of DI by 48%. QTLs from S. habrochaites LYC4 offer good perspectives for breeding B. cinerea resistant tomato cultivars.
    High-resolution fine mapping of ps-2, a mutated gene conferring functional male sterility in tomato due to non-dehiscent anthers
    Gorguet, B.J.M. ; Schipper, E.H. ; Heusden, A.W. van; Lindhout, P. - \ 2006
    Theoretical and Applied Genetics 113 (2006)8. - ISSN 0040-5752 - p. 1437 - 1448.
    jasmonic acid biosynthesis - lycopersicon-esculentum - arabidopsis - identification - regions - markers - mutant - aflp - map - polymorphism
    Functional male sterility is an important trait for the production of hybrid seeds. Among the genes coding for functional male sterility in tomato is the positional sterility gene ps-2. ps-2 is monogenic recessive, confers non-dehiscent anthers and is the most suitable for practical uses. In order to have tools for molecular-assisted selection (MAS) we fine mapped the ps-2 locus. This was done in an F2 segregating population derived from the interspecific cross between a functionally male sterile line (ps-2/ps-2; Solanum lycopersicum) and a functionally male fertile line (S. pimpinellifolium). Here we report the procedure that has led to the high-resolution fine mapping of the ps-2 locus in a 1.65 cM interval delimited by markers T0958 and T0635 on the short arm of Chromosome 4. The presence of many COS markers in the local high-resolution map allowed us to study the synteny between tomato and Arabidopsis at the ps-2 locus region. No obvious candidate gene for ps-2 was identified among the known functional male sterility genes in Arabidopsis
    A liquid chromatography-mass spectrometry-based metabolome database for tomato
    Moco, S.I.A. ; Bino, R.J. ; Vorst, O.F.J. ; Verhoeven, H.A. ; Groot, J.C.W. de; Beek, T.A. van; Vervoort, J.J.M. ; Vos, C.H. de - \ 2006
    Plant Physiology 141 (2006)4. - ISSN 0032-0889 - p. 1205 - 1218.
    steroidal alkaloid glycosides - solid-phase extraction - lycopersicon-esculentum - hydroxycinnamic acids - alpha-tomatine - quantitative-analysis - antioxidant activity - phenolic-compounds - fruit - vegetables
    For the description of the metabolome of an organism, the development of common metabolite databases is of utmost importance. Here we present the Metabolome Tomato Database (MoTo DB), a metabolite database dedicated to liquid chromatography-mass spectrometry (LC-MS)- based metabolomics of tomato fruit (Solanum lycopersicum). A reproducible analytical approach consisting of reversed-phase LC coupled to quadrupole time-of-flight MS and photodiode array detection (PDA) was developed for large-scale detection and identification of mainly semipolar metabolites in plants and for the incorporation of the tomato fruit metabolite data into the MoTo DB. Chromatograms were processed using software tools for mass signal extraction and alignment, and intensity-dependent accurate mass calculation. The detected masses were assigned by matching their accurate mass signals with tomato compounds reported in literature and complemented, as much as possible, by PDA and MS/MS information, as well as by using reference compounds. Several novel compounds not previously reported for tomato fruit were identified in this manner and added to the database. The MoTo DB is available at http://appliedbioinformatics.wur.nl and contains all information so far assembled using this LC-PDA-quadrupole time-of-flight MS platform, including retention times, calculated accurate masses, PDA spectra, MS/MS fragments, and literature references. Unbiased metabolic profiling and comparison of peel and flesh tissues from tomato fruits validated the applicability of the MoTo DB, revealing that all flavonoids and -tomatine were specifically present in the peel, while several other alkaloids and some particular phenylpropanoids were mainly present in the flesh tissue
    Differential effect of transpiration and Ca supply on growth and Ca concentration of tomato plants
    Amor, F.M. del; Marcelis, L.F.M. - \ 2006
    Scientia Horticulturae 111 (2006)1. - ISSN 0304-4238 - p. 17 - 23.
    lycopersicon-esculentum - glasshouse tomatoes - relative-humidity - calcium - accumulation - transport - salinity - leaves - fruit - crops
    To determine the extent to which transpiration and Ca concentration in the nutrient solution affect the regulation of growth, two independent experiments with young tomato plants were carried out under fully controlled climate conditions and grown hydroponically. The first experiment consisted of the regulation of transpiration by three levels of relative air humidity (RH): 50%, 70% (control) and 95% (corresponding to 1.32, 0.79 and 0.13 kPa, respectively) during 7 days. The second experiment involved four periods of 1, 3, 7 or 14 days of low-calcium (0.5 meq L¿1) compared with the nutrient standard solution (9 meq L¿1). The results show that plant growth was affected more by RH than by the reduction of Ca in the nutrient solution. High humidity reduced the total plant dry matter and total leaf area, increasing the dry matter partitioning into the stems and reducing it into the leaves. However, the low-Ca supply did not affect those parameters. Plant Ca concentration was significantly reduced by low-Ca supply as well as by high RH, but to a much greater extent by the Ca supply than by high RH. Ca concentrations in leaves, stem, and roots were quickly reduced already after 1 day of low-Ca. After 14 days, Ca concentration in all plant organs (leaves, stems and roots) was reduced by approximately 70% compared to control plants. Our data show that calcium supply, and consequently Ca concentration in the tomato plant can be reduced drastically for short-term periods during the vegetative growth stage without any adverse effect on growth whilst higher humidity reduce both growth and Ca concentration in young vegetative tomato plants. Consequently, reduced Ca uptake at high air humidity is not the cause for the reduction in growth. Keywords: Calcium; Transpiration; Dry matter partitioning; Leaf expansion; Lycopersicon esculentum Mill.
    Plant-mediated interactions between pathogenic microorganisms and herbivorous arthropods
    Stout, M.J. ; Thaler, J.S. ; Thomma, B.P.H.J. - \ 2006
    Annual Review of Entomology 51 (2006). - ISSN 0066-4170 - p. 663 - 689.
    yellow-dwarf-virus - systemic acquired-resistance - tobacco-mosaic-virus - rhopalosiphum-padi homoptera - white-backed planthopper - rice blast fungus - shared host-plant - botrytis-cinerea - arabidopsis-thaliana - lycopersicon-esculentum
    Plant-mediated interactions between pathogenic microorganisms and arthropod herbivores occur when arthropod infestation or pathogen infection changes the shared host plant in ways that affect a subsequent attacker of the opposite type. Interest in such "tripartite" interactions has increased as the ecological and plant physiological framework for understanding and contextualizing them has developed. The outcomes of plant-mediated interactions are variable, and only a few provisional patterns can be identified at present. However, these interactions can have important consequences not only for individual pathogens and herbivores, but also for the population dynamics of both types of organisms in managed and natural ecosystems. Research has focused on the role of two plant response pathways in mediating tripartite interactions, one involving jasmonic acid and the other salicylic acid. Further studies of plant-mediated interactions will facilitate an understanding of how plants coordinate and integrate their defenses against multiple biotic threats.
    Parthenocarpic fruit development in tomato
    Gorguet, B.J.M. ; Heusden, A.W. van; Lindhout, P. - \ 2005
    Plant Biology 7 (2005)2. - ISSN 1435-8603 - p. 131 - 139.
    jasmonic acid biosynthesis - gibberellin signal-transduction - low-temperature regime - male-sterile mutant - pisum-sativum l - natural parthenocarpy - agrobacterium-rhizogenes - severianin tomato - endogenous gibberellins - lycopersicon-esculentum
    Parthenocarpic fruit development is a very attractive trait for growers and consumers. In tomato, three main sources of facultative parthenocarpy, pat, pat-2, pat-3/pat-4, are known to have potential applications in agriculture. The parthenocarpic fruit development in these lines is triggered by a deregulation of the hormonal balance in some specific tissues. Auxins and gibberellins are considered as the key elements in parthenocarpic fruit development of those lines. An increased level of these hormones in the ovary can substitute for pollination and trigger fruit development. This has opened up genetic engineering approaches for parthenocarpy that have given promising results, both in quality and quantity of seedless fruit production
    Localization of jointless-2 gene in the centromeric region of tomato chromosome 12 based on high resolution genetic and physical mapping
    Budiman, M.A. ; Chang, S.B. ; Leel, S. ; Yang, T.J. ; Zhang, H.B. ; Jong, J.H.S.G.M. de; Wing, A. - \ 2004
    Theoretical and Applied Genetics 108 (2004)2. - ISSN 0040-5752 - p. 190 - 196.
    in-situ hybridization - lycopersicon-esculentum - pachytene chromosomes - metaphase chromosomes - meiotic pachytene - fish - dna - sequence - genome - plants
    Abscission is a universal process whereby plants shed their organs, such as flowers, fruit and leaves. In tomato, the non-allelic mutations jointless and jointless-2 have been discovered as recessive mutations that completely suppress the formation of pedicel abscission zones. A high resolution genetic map of jointless-2 was constructed using 1,122 jointless F2 plants. Restriction fragment length polymorphism (RFLP) marker RPD140 completely co-segregated with the jointless-2 locus and mapped in a 2.4 cM interval between RFLP markers CD22 and TG618. To chromosome walk to jointless-2, all three markers were used to screen a bacterial artificial chromosome (BAC) library and contigs were developed. Intensive efforts to expand and merge the BAC contigs were unsuccessful because of the highly repetitive sequence content on the distal ends of each contig. To determine the physical distance between and the orientation of the three contigs, we used high resolution pachytene fluorescence in situ hybridization (FISH) mapping. The RPD140 contig was positioned in the centromeric region of chromosome 12 between two large pericentric heterochromatin blocks, about 50 Mb from the TG618 contig on the short arm and 10 Mb from the CD22 contig on the long arm, respectively. Based on high resolution genetic and physical mapping, we conclude that the jointless-2 gene is located within or near the chromosome 12 centromere where 1 cM is approximately 25 Mb in length
    The development of lettuce backcross inbred lines (BILs) for exploitation of the Lactuca saligna (wild lettuce) germplasm
    Jeuken, M.J.W. ; Lindhout, W.H. - \ 2004
    Theoretical and Applied Genetics 109 (2004)2. - ISSN 0040-5752 - p. 394 - 401.
    mildew bremia-lactucae - lycopersicon-esculentum - downy mildew - resistance - tomato - gene - qtl - chromosome-1 - pennellii - serriola
    Backcross inbred lines (BILs) were developed in which chromosome segments of Lactuca saligna (wild lettuce) were introgressed into L. sativa (lettuce). These lines were developed by four to five backcrosses and one generation of selfing. The first three generations of backcrossing were random. Marker-assisted selection began in the BC4 generation and continued until the final set of BILs was reached. A set of 28 lines was selected that together contained 96% of the L. saligna genome. Of these lines, 20 had a single homozygous introgression (BILs), four had two homozygous introgressions (doubleBILs) and four lines had a heterozygous single introgression (preBILs). Segregation ratios in backcross generations were compared to distorted segregation ratios in an F-2 population, and the results indicated that most of the distorted segregations can be explained by genetic effects on pollen- or egg-cell fitness. By means of BIL association mapping we were able to map 12 morphological traits and hundreds of additional amplified fragment length polymorphic (AFLP) markers. The total AFLP map now comprises 757 markers. This set of BILs is very useful for future genetic studies.
    Toward a marker-dense meiotic map of the potato genome: lessons from linkage group I
    Isidore, E. ; Os, H. van; Andrzejewski, S. ; Bakker, J. ; Barrena, I. ; Bryan, G.J. ; Caromel, B. ; Eck, H.J. van; Ghareeb, B. ; Jong, W. de; Koert, P. van; Lefebvre, V. ; Milbourne, D. ; Ritter, E. ; Rouppe van der Voort, J.N.A.M. ; Rousselle-Bourgeois, F. ; Vliet, J.M. van; Waugh, R. - \ 2003
    Genetics 165 (2003). - ISSN 0016-6731 - p. 2107 - 2116.
    comprehensive genetic-map - comigrating aflp markers - dna methylation - lycopersicon-esculentum - tomato - plants - resistance - construction - population - strategy
    Segregation data were obtained for 1260 potato linkage group I-specific AFLP loci from a heterozygous diploid potato population. Analytical tools that identified potential typing errors and/or inconsistencies in the data and that assembled cosegregating markers into bins were applied. Bins contain multiple-marker data sets with an identical segregation pattern, which is defined as the bin signature. The bin signatures were used to construct a skeleton bin map that was based solely on observed recombination events. Markers that did not match any of the bin signatures exactly (and that were excluded from the calculation of the skeleton bin map) were placed on the map by maximum likelihood. The resulting maternal and paternal maps consisted of 95 and 101 bins, respectively. Markers derived from EcoRI/MseI, PstI/MseI, and SacI/MseI primer combinations showed different genetic distributions. Approximately three-fourths of the markers placed into a bin were considered to fit well on the basis of an estimated residual "error rate" of 0-3%. However, twice as many PstI-based markers fit badly, suggesting that parental PsiI-site methylation patterns had changed in the population. Recombination frequencies were highly variable across the map. Inert, presumably centromeric, regions caused extensive marker clustering while recombination hotspots (or regions identical by descent) resulted in empty bins, despite the level of marker saturation.
    Alteration of the genomic composition of Solanum nigrum (+) potato backcross derivatives by somatic hybridisation: selection of fusion hybrids by DNA measurements and GISH
    Horsman, K. ; Gavrilenko, T. ; Bergervoet, M. ; Huigen, D.J. ; Tjin Wong Joe, A. ; Jacobsen, E. - \ 2001
    Plant Breeding 120 (2001)3. - ISSN 0179-9541 - p. 201 - 207.
    infestans mont debary - lycopersicon-esculentum - chromosome-number - alien chromosomes - rflp analysis - tuberosum - brevidens - tomato - identification - resistance
    Fusion experiments were performed with a first (BC1-6738) and a second (BC2-9017) generation backcross hybrid of 6x Solanum nigrum (+) 2x potato somatic hybrids with potato cultivars. Because no progeny was obtained from the BC2 genotypes, alternative approaches were sought to overcome the sexual crossing barrier. Five potato genotypes, one of which contains the hygromycin resistance gene, were used in the fusion experiments. All vigorous regenerants were used for the estimation of nuclear DNA content using flow cytometry. Plants with a DNA content higher than that of the BC1-6738 or BC2 genotypes were considered potential somatic hybrids. Forty-nine potential somatic hybrids resulted from fusion experiments with BC1-6738, from which 20 grew vigorously in the greenhouse and flowered. After pollination with several 4x potato cultivars. eight genotypes produced seeded berries and five genotypes gave seedless berries. In addition. Il of these 13 somatic hybrids were selected for genomic in situ hybridization (GISH) analysis to determine their genomic composition. Nine had exactly or approximately the expected number of 36 S. nigrum and 60 potato chromosomes. In one genotype. only 22 instead of 36 S. nigrum chromosomes were found acid one potato chromosome was possibly missing. Only five potential somatic hybrids were detected among the 79 regenerants from BC2-9017 (+) 2x potato Fusion experiments that were analysed by flow cytometry. Two of these hybrids were rather vigorous and did flower, but pollinations with potato have not yet yet any berries.
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