Phylogenetic relationships within the phylum Nematoda as revealed by ribosomal DNA, and their biological implications
Holterman, M.H.M. - \ 2007
Wageningen University. Promotor(en): Jaap Bakker, co-promotor(en): Hans Helder. - [S.l.] : S.n. - ISBN 9789085048800 - 208
nematoda - ribosomaal dna - fylogenetica - klassering volgens erfelijke eigenschappen - fylogenie - plantenparasitaire nematoden - vrijlevende nematoden - dorylaimidae - chromadoridae - tylenchidae - zeenematoden - single nucleotide polymorphism - nematoda - ribosomal dna - phylogenetics - cladistics - phylogeny - plant parasitic nematodes - free living nematodes - dorylaimidae - chromadoridae - tylenchidae - marine nematodes - single nucleotide polymorphism
Nematodes – “eel worms”; members of the phylum Nematoda – can be considered as a success story within the Metazoa (multicellular, heterotrophic eukaryotes in which cells lack cell walls): they are speciose and – probably - the most numerous group of multicellular animals on our planet. Nematodes are present in virtually all terrestrial, freshwater and marine habitats. Nematodes are trophically diverse; they may feed on bacteria, fungi/oomycetes, algae and protozoa, other nematodes or on a combination of these (omnivores), or live as facultative or obligatory parasites of plants or animals. As they are abundant, ubiquitous and occupy several trophic levels, they play an important role in the soil food web. Nematode parasites of animals affect billions of humans and livestock, while plant parasites such as cyst, root knot and lesion nematodes cause large agricultural losses worldwide.
Despite their undisputed ecological and economical relevance, the systematics of the phylum Nematoda is far from established. One of the aims of this research was to further elucidate nematode phylogeny using molecular data. First a phylogenetic tree was constructed of 349 taxa, spanning the entire phylum Nematoda, on the basis of full length small subunit ribosomal DNA (SSU rDNA) sequences. A series of mostly well-supported bifurcations defined twelve major clades, whereas the most basal clade was defined by representatives of the Enoplida and Triplonchida. Our analysis confirmed the paraphyly of the Adenophorea. Furthermore it was found that the SSU rDNA from representatives of the distal clades evolved at a higher rate than the SSU rDNA from the basal clades. In the meantime, a substantial number of sequences was added to our overall SSU rDNA nematode alignment - both public data (GenBank) and data generated by ourselves (≈ 1,500 sequences in total; February 2008). It is noted that the clade division as proposed in 2006 on the basis of “only” 349 taxa still seems to be valid.
Subsequent research focused on three specific groups; Dorylaimia, Chromadoria and Tylenchomorpha. Within the suborder Dorylaimina, the SSU rDNA provided an exceptionally low phylogenetic signal, and - therefore – a part (≈ 1,000 bp) of the more variable large subunit ribosomal DNA (LSU rDNA) was analyzed. In most cases nematode relationships could be elucidated with good support, although some areas in the trees remained unresolved. Generally speaking the results of molecular phylogenetics corresponded fairly well with classical nematode taxonomy. The main exception was the order Dorylaimida where twelve subclades could be distinguished which bore little resemblance to classical taxonomy. Furthermore the suitability of ribosomal DNA for a (semi-) quantative molecular identification method was demonstrated using quantitative PCR (q-PCR) and primers designed to specifically amplify members of the order Mononchida and the potato cyst nematodes Globodera pallida and G. rostochiensis.
Plant parasitism has arisen several times within the phylum Nematoda (once in the Triplonchida, at least three times in the Dorylaimida and at least twice in the Tylenchomorpha). The long-standing and generally accepted hypothesis states that plant parasites evolved from fungal feeding ancestors. However, while in most cases plant parasites were associated with fungal feeding nematodes, this hypothesis could neither be confirmed nor denied with the results of our phylogenetic analyses. In the case of two Dorylaimida (Pungentus and Longidorella), however, the ancestor was probably an omnivore. The analysis of this problem was substantially hampered by the lack of knowledge on feeding behavior of basal Tylenchomorpha.
Presumably, the common ancestor of the nematodes lived in a marine environment and - if this assumption is correct - the transition to a limnoterrestrial environment must have taken place at least once. Surprisingly, analysis of the Chromadoria (minus the Rhabditida) revealed that transitions from a thalassic to a limnoterrestrial habitat (and vice versa) have taken place at least 11 times in the Chromadoria. Given their frequency these transitions are apparently fairly easy to achieve for nematodes and the possible adaptations involved were discussed.
Nematodes vary widely in their responses to environmental disturbance, making them good bio-indicators of soil health. Yet it is not known with certainty which traits are responsible for tolerance to stress in nematodes. A framework was laid out to study correlations between nematode traits and stress tolerance. Furthermore the importance of accounting for the confounding effects of phylogeny was demonstrated. This is a first step towards a transparent, ecological grouping of free-living nematodes.
It is worthwhile mentioning that - on the basis of the rDNA-based molecular framework described in this PhD thesis - DNA sequences signatures were identified for nearly all North-West European terrestrial and freshwater nematodes families. The relationship between quantitative PCR signal and numbers of individuals has been established for nearly all families and a first testing of DNA barcode-based community analysis is planned for spring 2008.
|Nematoda, Secernentea(Tylenchida, Aphelenchida)
Loof, P.A. - \ 2001
Heidelberg : Spektrum Akademischer Verslag - ISBN 9783827410719 - 246
nematoda - vrijlevende nematoden - zoet water - dieranatomie - morfologie - determinatietabellen - identificatie - verzamelen - aphelenchidae - tylenchidae - taxonomie - centraal-europa - nematoda - free living nematodes - fresh water - animal anatomy - morphology - keys - identification - collection - aphelenchidae - tylenchidae - taxonomy - central europe
Het testen van opgeschaalde Seinhorst-opspoelkannen
Bekkum, P.J. van; Beers, T.G. van; Beniers, J.E. - \ 2000
Gewasbescherming 31 (2000)3. - ISSN 0166-6495 - p. 65 - 67.
aardappelen - dieren - populatiedichtheid - populatie-ecologie - mortaliteit - populatiegroei - ziekteresistentie - plaagresistentie - fysica - meting - methodologie - ? - globodera - potatoes - pratylenchus - heteroderidae - tylenchidae - animals - population density - population ecology - mortality - population growth - disease resistance - pest resistance - physics - globodera
Om een voldoende grote statistische betrouwbaarheid voor de bepaling van populatiedichtheden van Globodera spp. in wetenschappelijke experimenten of bij het testen van aardappelcultivars ten behoeve van hun partiele resistentie-eigenschappen te verkrijgen, is het nodig om zowel de begin- als de einddichtheid van het aaltje nauwkeurig te bepalen. Twee methoden voor de bepaling van de relative vatbaarheid van aardappelrassen voor aardappelcysteaaltjes worden vergeleken
Grote verschillen : waardplantgeschiktheid van akkerbouwgewassen, grove groenten en groenbemestingsgewassen voor Meloidogyne fallax en meloidogyne chitwoodi
Molendijk, L.P.G. ; Nijboer, H. - \ 1998
PAV-bulletin. Vollegrondsgroenteteelt / Praktijkonderzoek voor de Akkerbouw en de Vollegrondsgroenteteelt 1998 (1998)1. - ISSN 1385-5298 - p. 24 - 25.
gastheerreeks - plantenziekten - plantenplagen - bodem - nematoda - pratylenchus - heteroderidae - tylenchidae - groenbemesters - host range - plant diseases - plant pests - soil - nematoda - pratylenchus - heteroderidae - tylenchidae - green manures
Potato crop growth as influenced by potato cyst nematodes (Globodera pallida) and abiotic factors
Ruijter, F. de - \ 1998
Agricultural University. Promotor(en): G.R. Findenegg; A.J. Haverkort. - S.l. : De Ruijter - ISBN 9789054858195 - 121
solanum tuberosum - aardappelen - plantenplagen - pratylenchus - heteroderidae - tylenchidae - bodem - nematoda - solanum tuberosum - potatoes - plant pests - pratylenchus - heteroderidae - tylenchidae - soil - nematoda
The objective of the research described in this thesis was to determine the major mechanisms by which potato cyst nematodes reduce potato crop growth and to explain interactions known to occur with cultivar and abiotic factors. Understanding of these interactions may lead to strategies that potato growers can use to minimise nematode damage.
The research concentrated on the interaction between nematodes and soil-related factors. Experiments were carried out, mainly under field conditions, in which the effects of varying levels of nematode density, soil compaction, soil pH and phosphorus fertilisation on crop growth of potato cultivars were studied over time. Two methods for studying root growth in the field were compared and special attention was paid to the effects of nematodes on root growth.
It was found that potato cyst nematodes reduced crop growth at early stages of growth by inducing or aggravating phosphorus deficiency. Compensatory root growth alleviated phosphorus deficiency at later stages of growth. Application of phosphorus fertiliser reduced or prevented nematode-induced phosphorus deficiency, but could not fully prevent nematode damage. Obviously, penetration of nematodes in the roots also impaired crop photosynthesis also through mechanisms other than nutrient deficiency.
At late stages of growth, nematodes accelerated crop senescence. This was associated with reduced concentrations of nutrients in the foliage, though it seems likely that more mechanisms could be responsible. To resolve this, further study of the senescence of infested crops and options for remedying this is required.
It was found that tolerance of cultivars to potato cyst nematodes is associated with production of extra roots and large tops, a characteristic of late maturing potato cultivars. The influence of soil parameters on nematode damage was also found to depend on the amount of foliage produced. It is inferred that crops with large tops suffer little yield loss as they are able to maintain ground cover and light interception, even after infestation by potato cyst nematodes.
It is concluded that farmers can minimise yield loss by choosing tolerant cultivars and by cultural measures. It is suggested that initial nematode-induced phosphorus deficiency can be relieved by fertilisation methods that increase phosphorus in infested plants to adequate levels. Crop senescence may be delayed by increasing nitrogen in infested plants, e.g. by foliar application of a nitrogen fertiliser, but this requires further study.
Genetic diversity of the potato cyst nematode in the Netherlands
Folkertsma, R.T. - \ 1997
Agricultural University. Promotor(en): R.W. Goldbach; F.J. Gommers; J. Bakker. - S.l. : Folkertsma - ISBN 9789054857488 - 88
plantenplagen - pratylenchus - heteroderidae - tylenchidae - solanum tuberosum - aardappelen - genetische variatie - overerving - rassen (dieren) - rassen (taxonomisch) - moleculaire genetica - plantenveredeling - ziekteresistentie - plaagresistentie - globodera pallida - globodera rostochiensis - plant pests - pratylenchus - heteroderidae - tylenchidae - solanum tuberosum - potatoes - genetic variation - inheritance - breeds - races - molecular genetics - plant breeding - disease resistance - pest resistance - globodera pallida - globodera rostochiensis
The potato cyst nematodes Globodera rostochiensis (Woll.) Skarbilovich and G. pallida (Stone) originate from the Andes region in South America and have been introduced into Western Europe since 1850. Both species are successful colonizers. Once primary founders have established vital populations, an area is rapidly colonized by secondary founding events. The mode of spread results in patchy distribution patterns. Analyses of the processes that influence the spatial variations in virulence are of major importance for the control by means of host plant resistance. The ability to unravel the mosaic distribution patterns of the two species and their pathotypes enables breeders and growers to anticipate on the dynamics of virulent populations. The aim of this thesis was to analyse the intra- and interspecific variation of G. rostochiensis and G. pallida in the Netherlands and to obtain insight in the processes that determine the spatial variations in protein, DNA and (a)virulence polymorphisms.
The molecular variation between the sibling species G.rostochiensis and G.pallida is remarkably large. The RAPD technique revealed a total of 250 DNA fragments, of which only nine DNA fragments were common to both species (Chapter 3). Similar results were obtained with the AFLP assay. A total of 1000 AFLP fragments was amplified, of which only 64 fragments could be identified in both species (Chapter 4). These results agreed with previous investigations using 2-DGE and show that morphologically nearly indistinguishable organisms can be quite distinct the molecular level.
The extensive genetic differentiation of G.rostochiensis and G . pallida offers perspectives for the development of a diagnostic assay. In addition the PCR technique enables the amplification of species specific fragments from small numbers of cysts extracted from soil samples. For example, G. rostochiensis specific DNA fragments can be amplified from single juveniles (Chapter 1).
The intraspecific variation of G.rostochiensis as revealed by RAPDs and AFLPs is relatively low (Chapter 3 and 4). The proportion of polymorphic DNA fragments among nine G. rostochiensis populations was 19% and 15.8%, respectively. Three clusters of populations were identified and each cluster could be described by one or more specific DNA fragments.
The intraspecific variation of G.pallida, as revealed with RAPDs or AFLPs, is larger in comparison with G.rostochiensis (Chapter 3 and 4). The proportion of polymorphic RAPD fragments among 17 populations was 46%. For the AFLP assay this figure was 23% polymorphic AFLP fragments among 15 populations. The majority of the populations displayed a continuous range of variations. Only a few clearly diverged clusters could be discriminated on the basis of specific DNA fragments.
Various groups have applied the RAPD technique to study the genetic divergence among conspecific populations of plant parasitic nematodes. The validity of this technique was evaluated in chapter 4 by comparison of the clustering of 36 G.pallida populations based on RAPD and 2-DGE data. Both data sets demonstrated that the majority of the G.pallida populations were not clearly differentiated from each other. The overall correlation between the distance matrices derived from both data sets was low. Careful examination of the separate dendrograms showed similarity in clustering only for clearly diverged populations or groups of populations.
Although the AFLP and RAPD technique are simple, fast and require only minute amounts of biological material, they are not suitable to resolve the subtle differences among potato cyst nematode populations. Quantitative variation in allele frequencies is often not resolved with those techniques, which is, among others, due to the virtual inability to recognize co-dominant alleles and the non-linear amplification of DNA fragments. In chapter 6 and 7 the genetic variation was studied by analysing pools of individuals with 2-DGE. The ratios between the protein quantities produced by the codominant alleles are appropriate measures for the allele frequencies. The correctness of this method has been confirmed by 2-DGE of single individuals (De Boer etal ., 1992)
bottleneck effects on the secondary founders
The intraspecific variation among potato cyst nematode populations in Europe is predominantly determined by the genetic constitution of the primary founders, directly or indirectly introduced from South America, and the effect of random genetic drift on the secondary founders. To obtain insight in these processes, 226 G.pallida populations from the Netherlands were analyzed with 2- DGE. The results strongly suggest that these populations originate from one source, or in case of multiple introductions, from a number of sources with a similar genetic makeup.
The genetic differentiation of the 226 G.pallida populations indicate that the colonization of the Netherlands has been accompanied by extensive random genetic drift. Only a limited proportion of the populations appeared to be identical. It is also shown, that the bottleneck effects differ between regions. Significant variation in population structure was observed between the three investigated areas. The genetic variation within G.pallida populations from north Friesland and the IJsselmeerpolders is in general smaller than within populations from the northeast Netherlands. A plausible explanation for this phenomena is the low multiplication rate of potato cyst nematodes due to wider crop rotation schemes in the IJsselmeerpolders and north Friesland. These factors result in a slow expansion of newly founded populations, which enhances the effect of drift.
gene-pool similarity concept
The gene-pool similarity concept rests on the hypothesis that in the absence of selection pressure by host plant resistance, degrees of similarity between populations revealed by molecular techniques are also reflected at virulence loci, including those not yet resolved. To test this concept, the genetic variation revealed by 2-DGE among 102 G.pallida populations was compared with the variation in virulence towards two resistant cultivars. This analysis showed that a decrease in genetic distance among populations is accompanied with a decrease in variation in virulence. In addition it is demonstrated that the gene pool similarity concept is also applicable to loci determining the variation in fitness among populations. The variation in Pf/Pi values among the 102 populations on Désirée is in general smaller between closely related populations than between distantly related populations.
breeding for resistance
Breeding for resistance has been dominated by trial-and-error approaches, which has stimulated the view that control by means of host plant resistance is unavoidably a short-term approach due to the 'appearance' of virulent populations. The pervasive myth that breeding for resistance against potato cyst nematodes is a lost arms race is challenged by the results of this thesis. Until recently it was assumed that the genetic variation of G.pallida in the Netherlands was too large to produce potato cultivars with broad-spectrum resistance. In this thesis it is shown that the genetic diversity introduced from the Andes region has been limited and that the variation among the Dutch G.pallida populations is mainly the result of random genetic drift. The elaborate analysis of 226 Dutch G.pallida populations offers perspectives to obtain potato cultivars with broad and durable resistance. The gene pool similarities revealed by 2-DGE can be used as guidance in testing the effectiveness of new sources of resistance.
Resistance to root-knot nematodes, Meloidogyne spp., in potato
Janssen, G.J.W. - \ 1997
Agricultural University. Promotor(en): E. Jacobsen. - S.l. : Janssen - ISBN 9789054856764 - 111
plantenveredeling - ziekteresistentie - plaagresistentie - solanum tuberosum - aardappelen - plantenplagen - pratylenchus - heteroderidae - tylenchidae - plant breeding - disease resistance - pest resistance - solanum tuberosum - potatoes - plant pests - pratylenchus - heteroderidae - tylenchidae
Root-knot nematodes, Meloidogyne spp., are world-wide one of the most damaging pests to arable farming. In North Western Europe, the species M. chitwoodi, M. fallax and M. hapla are becoming a serious problem in potato growing areas as a result of recent changes in crop rotation, that now include highly profitable host crops, and a reduced use of nematicides in potato. The root-knot nematodes can cause yield reduction and deteriorate the quality of the tuber to an unmarketable product. Since root-knot nematodes can multiply inside the tuber, infected potato tubers are a threat to infest Meloidogyne-free fields. To prevent this way of dispersal, quarantine measures will be in force for seed tubers in the countries of the European Community from August 1997.
Plant resistance is an effective, economical and environmentally safe alternative to control root-knot nematodes, but resistance is lacking in the presently used potato cultivars. The goal of the research described in this thesis was to identify and evaluate sources of resistance to M. chitwoodi, M. fallax and M. hapla and, if present, to initiate the transfer of resistance into cultivated potato.
A large screening of wild Solanum spp. was performed to identify sources of resistance to M. chitwoodi, M. fallax and/or M. hapla by selecting seedlings, which showed no to hardly any reproduction of the nematodes on the roots. High levels of resistance to both M. chitwoodi and M. fallax were observed in genotypes of S. bulbocastanum, S. cardiophyllum, S. brachistotrichum, S. fendleri and S. hougasii, whereas additionally moderate resistance to M. fallax was present in S. stoloniferum and S. chacoense and to M. chitwoodi in S. gourlayi. More Solanum species were selected with resistance to M. hapla, namely S. bulbocastanum, S. brachistotrichum, S. cardiophyllum, S. arnezii, S. chacoense, S. tarijense, S. boliviense, S. gourlayi, S. microdontum, S. sparsipilum, S spegazzinii, S. sucrense, S. acaule and S. hougasii. In general, resistance to M. chitwoodi and M. fallax was restricted to Solanum species originating from Central America, whereas resistance to M. hapla was present in numerous Central- and South American Solanum species. This might indicate that co-evolution has occurred between M. chitwoodi and related M. fallax and Central American Solanum species.
The following step was the evaluation of resistance with regard to the effectivity and working spectrum. In a glasshouse, resistant and susceptible Solanum genotypes were tested with two to four populations of M. chitwoodi, M. fallax and M. hapla to determine the level of resistance and to detect the presence of virulent populations within these Meloidogyne species. Resistant genotypes of S. bulbocastanum, S. hougasii, S. cardiophyllum and S. fendleri showed an almost absolute level of resistance and were able to suppress all populations of M. chitwoodi and M. fallax tested. Some genotypes of S. chacoense and S. stoloniferum showed moderate resistance to M. fallax, but not or in a lesser extent to M. chitwoodi. In contrast, large differences in virulence were observed between the four tested populations of M. hapla on resistant genotypes of S. bulbocastanum, S. hougasii, S. chacoense, S. gourlayi, S. sparsipilum and S. spegazzinii. Some genotypes with resistance to M. chitwoodi, M. fallax andlor M. hapla were also tested against isolates of the tropical and subtropical Meloidogyne species M. incognita, M. arenaria and M. javanica, but resistance was not effective to these high temperature adapted species.
The effectivity of resistance of some selected wild Solanum species was also evaluated under natural field conditions. In two fields in the Netherlands, naturally infested with M. hapla or M. fallax, the level of infection of soil surrounding resistant and susceptible genotypes was followed during a growing season. From August onwards, large differences in number of second-stage juveniles were present between resistant and susceptible genotypes. At the end of the growing season, the level of infection in soil of resistant wild Solanum genotypes was equal or lower compared to the beginning, whereas soil surrounding susceptible wild and cultivated genotypes showed a 7- to 22-fold increase of nematode infection. The results were comparable with the resistance tests in glasshouse experiments.
An important feature for a rapid introgression of resistance is the inheritance and this has been investigated for the resistance to M. chitwoodi and M. fallax in S.fendleri, S. hougasii and S. stoloniferum. Although these Solanum species are polyploid, a disomic genetic behaviour can be expected as earlier indicated by cytogenetic and genetic studies. Various populations were produced from crosses between resistant and susceptible plants, self- pollinations and backcrosses within the wild Solanum species and segregation patterns of progenies in resistant and susceptible plants were analysed. The progeny tests of S. fendleri clearly indicated the action of a single dominantly inherited gene, effective against both M. chitwoodi and M. fallax, and the symbol R mc2 is proposed for this gene. In the case of S. hougasii, difficulties were met in producing backcross populations, but results also indicated the presence of a simple dominant factor for both nematode species. From the results of progeny tests of S. stoloniferum, it was concluded that several additive genes are involved.
The introgression of resistance from various wild Central American Solanum species into the cultivated potato has been initiated through interspecific hybridisation. Crosses were made between diploid S. tuberosum and diploid S. bulbocastanum, S. brachistotrichum and S. cardiophyllum, but no plants were obtained from these crosses. From crosses of tetraploid S. tuberosum with tetraploid S. stoloniferum and S. fendleri, and of diploid S. tuberosum with hexaploid S. hougasii few seeds leading to tetraploid hybrids were obtained, sometimes after in vitro culture of immature seeds. The hybrid status was confirmed with RAPD markers and the ploidy level was analysed using flow cytometry. These cross combinations were thought not to be possible according to the Endosperm Balance Number hypothesis and the hybrids obtained are considered to be escapes. Backcrosses were made and a variable number of seeds leading to first backcrossed genotypes (BC 1 's) was produced depending on the hybrid genotype. The introgression of resistance to root-knot nematodes from S.fendleri, S. stoloniferum and S. hougasii has now advanced to the evaluation of resistant BC 1 's for other traits before continuation of further backcrosses.
In conclusion, resistance to the root-knot nematodes M. chitwoodi, M. fallax and M. hapla has been identified in various Solanum species and has the potential to become an effective tool to control these pathogens under field conditions after transfer into cultivated potato. The first steps of introgression of resistance into S. tuberosum has been made. The introduction of multiple sources of resistance in new potato cultivars will enable a resistance management based on durable exploitation of useful resistance genes from natural resources.
|Aktiviteit van trichodoride aaltjes : een sleutel voor de beheersing van tabaksratelvirus : eindverslag van het projekt 'Overleving en aktiviteit van virusoverdragende nematoden (Trichodoridae) in de bloembollenteelt'
Zoon, F.C. ; Pavlickova, E. ; Heij, A. de - \ 1996
Wageningen : IPO-DLO (Urgentieprogramma bollenziekte- en veredelingsonderzoek ) - 20
experimenten - heteroderidae - nederland - bloembollen - plantenziekten - plantenplagen - gewasbescherming - plantenvirussen - pratylenchus - onderzoek - tabaksratelvirus - tylenchidae - trichodoridae - experiments - heteroderidae - netherlands - ornamental bulbs - plant diseases - plant pests - plant protection - plant viruses - pratylenchus - research - Tobacco rattle virus - tylenchidae - trichodoridae
Populatiedynamica van het wortellesie-aaltje (Pratylenchus penetrans) in de boom- en fruitteelt
Schepman, M.A. - \ 1996
Boskoop : Proefstation voor de Boomkwekerij (Rapport / Boomteeltpraktijkonderzoek 41) - 53
vruchtbomen - heteroderidae - nederland - boomgaarden - houtachtige planten als sierplanten - plantenplagen - pratylenchus - tylenchidae - fruit trees - heteroderidae - netherlands - orchards - ornamental woody plants - plant pests - pratylenchus - tylenchidae
Eindevaluatie programma bodemgezondheid (Terra)
Anonymous, - \ 1996
Lelystad etc. : PAGV [etc.] - 40
aardappelen - solanum tuberosum - heteroderidae - nematoda - tylenchidae - gewasbescherming - nederland - potatoes - solanum tuberosum - heteroderidae - nematoda - tylenchidae - plant protection - netherlands
Doel is de grondontsmetting tegen het aardappelcystenaaltje zodanig terug te brengen, dat de MJP-G doelen op dit gebied gerealiseerd kunnen worden. De natte grondontsmetting is in deze periode met 77% verminderd volgens de Nefyto -gegevens
|Er is een relatie tussen calciumgehalte en tolerantie
Haverkort, A.J. ; Ruijter, F. de; Boerma, M. ; Waart, M. van de - \ 1996
Aardappelwereld 50 (1996)12. - ISSN 0169-653X - p. 51 - 53.
calcium - cultivars - vroegheid - heteroderidae - nematoda - plantenveredeling - aardappelen - pratylenchus - rassen (taxonomisch) - bodem - solanum tuberosum - tylenchidae - rassen (planten) - calcium - cultivars - earliness - heteroderidae - nematoda - plant breeding - potatoes - pratylenchus - races - soil - solanum tuberosum - tylenchidae - varieties
Towards identification of oesophageal gland proteins in Globodera rostochiensis
Boer, J.M. de - \ 1996
Agricultural University. Promotor(en): R.W. Goldbach; F.J. Gommers. - S.l. : De Boer - ISBN 9789054855408 - 144
chemotaxonomie - plantenplagen - pratylenchus - heteroderidae - tylenchidae - eiwitten - lymfe - excretie - secretie - klieren (dier) - chemotaxonomy - plant pests - pratylenchus - heteroderidae - tylenchidae - proteins - lymph - excretion - secretion - glands (animal)
Secretory proteins from the dorsal and subventral oesophageal glands of potato cyst- nematodes (Globodera rostochiensis and G.pallida ) are considered to play an important role in the induction and exploitation of the specialized feeding cells (syncytia) that these parasites establish in the roots of their host plant. Identification of these secretory proteins will provide insight into the mechanisms involved in the formation of these syncytia, and is likely to aid in the development of novel forms of (artificial) host plant resistance to potato cyst-nematode infection. This thesis presents the data which were collected during a search for the oesophageal gland secretory proteins of G.rostochiensis.
In the first part of the investigations (Chapters 2 to 5) the proteins of G.rostochiensis are examined using two-dimensional gel electrophoresis (2D-GE) followed by silver staining. Chapter 2 compares the protein patterns of two motile (2nd-stage juveniles (J2) and males) and two sedentary (4th-stage females and adult females) developmental stages using conventional (2D-GE) in large gels. This demonstrated very large differences in protein composition between these four developmental stages, and it was estimated that 74% of the polypeptides visible in these gels showed variations in their presence or abundance. The highest similarity index values were calculated for the protein patterns of both motile stages (0.674) and of both sedentary stages (0.767) with decreased values for all other pairwise comparisons.
Chapter 3 introduces a miniature 2D-GE technique of which the high sensitivity is demonstrated by its ability to genotype single females of G. pallida . In Chapter 4 this mini 2D-GE technique is used to analyse the proteins of the complete range of post-embryonic developmental stages of G. rostochiensis. This analysis demonstrated large changes in protein pattern during the transformation of preparasitic J2 into sedentary J3 and during the metamorphosis of males into adults. The changes in abundance of three muscle proteins showed that during these two events the body-wall musculature is respectively broken down and restored. It is concluded that 4th-stage male juveniles complete their metamorphosis to adults using protein resources that they have aqcuired while feeding as 2nd- and 3rd-stage juveniles. From the occurrence of several characteristic dominant proteins in the male juvenile stages it is postulated that cyst-nematodes may use a system of storage proteins to complete the different phases of their life-cycle.
Because of the large differences between the 2D-GE patterns of the developmental stages examined in Chapters 2 and 4, it was not possible to identify putative oesophageal gland proteins in these gels. Therefore, in Chapter 5 adult males and J2 are dissected into anterior parts (containing the oesophageal glands) and posterior parts (without the glands) and the protein composition of these body fragments. is analysed using mini 2D- GE. This identified a single polypeptide of 34.4 kDa which was characteristic of the anterior part of both J2 and males. Although this protein may originate from an oesophageal gland, this could not be confirmed with certainty, and other explanations for its origin remain as yet equally plausible.
The second part of the investigations (Chapters 6 and 7) describes the production of monoclonal antibodies (MAbs) against antigens from G.rostochiensis with the aim to identify oesophageal gland proteins. In Chapter 6 mice were immunized with antigen samples derived from preparasitic J2 and fourthstage females, and MAbs produced by hybridoma cell lines were screened with immunofluorescence microscopy for reactivity with structures within J2. This identified MAbs with various binding specificities, including 5 MAbs which reacted strongly with the subventral oesophageal glands. Unfortunately, these latter MAbs did not identify oesophageal gland proteins on Western blots of J2, indicating that their epitopes were sensitive to denaturation by the electrophoresis detergent SDS.
In Chapter 7 mice were therefore immunized with partially purified SDS-denatured proteins from J2, which had been collected by preparative continuous flow electrophoresis. This produced 12 new MAbs against the subventral glands, of which 11 reacted with proteins on Western blots of J2. Together these MAbs identified 4 proteins of respectively 30, 31, 39 and 49 kDa. Immunoelectron microscopy with one of these MAbs showed a specific binding to the contents of the secretory granules within the subventral glands of J2, indicating that these proteins are indeed the secretory products of these gland cells. It is discussed in Chapter 7 that the antibodies to the subventral gland proteins may be useful for engineering resistance to cyst-nematodes into potato by means of 'plantibody' technology.
The MAbs to the oesophageal gland proteins from Chapter 7 will be valuable tools in future studies relating to the nature of these antigens and their possible function in the host-parasite interaction. In a following thesis by colleague G. Smant results of such further studies will be presented, and this will include the identification of the abovementioned subventral gland proteins in 2D-gels of G. rostochiensis.
|Methoden voor bepaling van de relatieve vatbaarheid van aardappelrassen voor aardappelcysteaaltjes in de kas
Beniers, A. - \ 1995
Wageningen : CPRO-DLO - 41
ziekteresistentie - heteroderidae - plaagresistentie - plantenveredeling - plantenplagen - aardappelen - pratylenchus - solanum tuberosum - tylenchidae - disease resistance - heteroderidae - pest resistance - plant breeding - plant pests - potatoes - pratylenchus - solanum tuberosum - tylenchidae
|Langdurige bewaring van wortelknobbelaaltjes bij -196 °C
Veldhuis, W.B.J. ; Beek, J.G. van der; Zijlstra, C. ; Silfhout, C.H. van - \ 1995
Gewasbescherming 26 (1995)2. - ISSN 0166-6495 - p. 64 - 67.
ziekteresistentie - genetische variatie - genetica - heritability - heteroderidae - plaagresistentie - plantenveredeling - plantenplagen - pratylenchus - bescherming - onderzoek - opslag - tylenchidae - wetenschap - wetenschappelijk onderzoek - disease resistance - genetic variation - genetics - heritability - heteroderidae - pest resistance - plant breeding - plant pests - pratylenchus - protection - research - storage - tylenchidae - science - scientific research
Ter ondersteuning van het veredelen op resistentie vindt op het DLO-instituut voor Plantenziektenkundig Onderzoek virulentieonderzoek aan wortelknobbelaaltjes plaats. Verschillende populaties worden onderzocht op virulentie en andere eigenschappen. Het instandhouden van deze populaties is problematisch. Om die reden is gezocht naar een vorm van langdurige bewaring, waarbij de uitgangspopulatie later ook nog beschikbaar is, hetgeen belangrijk kan zijn voor genetisch onderzoek
|An advisory system for the management of potato cyst nematodes (Globodera spp)
Been, T.H. ; Schomaker, C.H. ; Seinhorst, J.W. - \ 1995
In: Potato ecology and modelling of crops under conditions limiting growth : proceedings of the second international potato modeling conference, held in Wageningen 17 - 19 May, 1994 / Haverkort, A.J., MacKerron, D.K.L., - p. 305 - 355.
automatisering - computersimulatie - heteroderidae - nematoda - planning - aardappelen - pratylenchus - simulatie - simulatiemodellen - bodem - solanum tuberosum - tylenchidae - automation - computer simulation - heteroderidae - nematoda - planning - potatoes - pratylenchus - simulation - simulation models - soil - solanum tuberosum - tylenchidae
|Invloed van diflubenzuron en Steinernema feltiae op de opbrengst van de champignon Agaricus bisporus
Scheepmaker, J.W.A. ; Geels, F.P. ; Smits, P.H. - \ 1995
De Champignoncultuur 39 (1995)2. - ISSN 0009-1316 - p. 55 - 59.
gewasbescherming - insecticiden - acariciden - mollusciciden - agaricus - oogsttoename - oogstverliezen - opbrengsten - insecten - plantenplagen - compost - groeimedia - culicidae - chironomidae - cecidomyiidae - tabanidae - dolichopodidae - bombyliidae - stratiomyidae - phoridae - pratylenchus - heteroderidae - tylenchidae - nematocera - brachycera - plant protection - insecticides - acaricides - molluscicides - agaricus - yield increases - yield losses - yields - insects - plant pests - composts - growing media - culicidae - chironomidae - cecidomyiidae - tabanidae - dolichopodidae - bombyliidae - stratiomyidae - phoridae - pratylenchus - heteroderidae - tylenchidae - nematocera - brachycera
Nematoden ter bestrijding van de champignonmug en de champignonvlieg. Ze vormen een alternatief voor de chemische bestrijding met het insekticide diflubenzuron
|A growth model for plants attacked by nematodes
Schomaker, C.H. ; Been, T.H. ; Seinhorst, J.W. - \ 1995
In: Potato ecology and modelling of crops under conditions limiting growth : proceedings of the second international potato modeling conference, held in Wageningen 17 - 19 May, 1994 / Haverkort, A.J., MacKerron, D.K.L., - p. 197 - 214.
computersimulatie - heteroderidae - nematoda - aardappelen - pratylenchus - simulatie - simulatiemodellen - bodem - solanum tuberosum - tylenchidae - oogsttoename - oogstverliezen - opbrengsten - computer simulation - heteroderidae - nematoda - potatoes - pratylenchus - simulation - simulation models - soil - solanum tuberosum - tylenchidae - yield increases - yield losses - yields
Mapping and characterisation of quantitative trait loci conferring nematode resistance in Solanum spegazzinii
Kreike, C.M. - \ 1995
Agricultural University. Promotor(en): C. Heyting; W.J. Stiekema. - S.l. : Kreike - ISBN 9789054854081 - 103
solanum tuberosum - aardappelen - plantenplagen - pratylenchus - heteroderidae - tylenchidae - chromosoomkaarten - genkartering - genetische modificatie - recombinant dna - plantenveredeling - ziekteresistentie - plaagresistentie - planten - globodera - solanum tuberosum - potatoes - plant pests - pratylenchus - heteroderidae - tylenchidae - chromosome maps - gene mapping - genetic engineering - recombinant dna - plant breeding - disease resistance - pest resistance - plants - globodera
This thesis describes the mapping and characterisation of QTLs, in Solanum spegazzinii, that are involved in resistance to the potato cyst-nematodes Globodera rostochiensis and G. pallida. For this purpose an RFLP linkage map of potato is constructed based on the offspring from non-inbred parents. Phenomena like distorted segregation and reduced recombination that are observed during linkage analysis are discussed. Several QTLs are mapped that are involved in resistance to G.rostochiensis and one major QTL that is involved in resistance to G.pallida. Single point analysis and interval mapping are employed for the localisation of the QTLs. Other quantitative traits like tuber yield and root development are mapped as well. In addition a method is described for the nonradioactive detection of single copy DNA-DNA hybrids.
Molecular characterization of the beet cyst nematode (Heterodera schachtii) resistance locus Hs1
Salentijn, E.M.J. - \ 1995
Agricultural University. Promotor(en): A. van Kammen; W.J. Stiekema. - S.l. : Salentijn - ISBN 9789054853930 - 119
beta vulgaris - suikerbieten - plantenveredeling - ziekteresistentie - plaagresistentie - moleculaire biologie - plantenziektekunde - plantenplagen - pratylenchus - heteroderidae - tylenchidae - moleculaire genetica - beta vulgaris - sugarbeet - plant breeding - disease resistance - pest resistance - molecular biology - plant pathology - plant pests - pratylenchus - heteroderidae - tylenchidae - molecular genetics
The white beet cyst nematode (BCN), Heterodera schachtii Schm. is a serious pest in sugar beet ( B. vulgaris L.) cultivation and is widely distributed throughout most of the beet-growing areas in the world (Cooke 1987). The economical losses due to infestation with the nematode are considerable (approximately 1200 dutch guilders or $ 600 per ha. at a rate of 25 % -30 % loss) and can mainly be ascribed to the intensive growing of sugar beet and other crops like oilseed rape which allow the nematode to multiply. The damage consists of wilting and a loss in root yield and sugar content (Mesken & Lekkerkerker 1988). Due to the lack of paying non-host crops to widen the rotation scheme, control of the beet cyst nematode population relies heavily on the use of nematicides. An alternative way, in which control might be achieved, is the use of resistant varieties. However, breeding for nematode resistance in sugar beet is extremely difficult and time consuming and did not yet result in stable nematode resistant material. Nevertheless, from crosses between sugar beet and BCN resistant wild beets three types of BCN resistant plants were obtained: monosomic additions, monosomic fragment additions and diploid introgressions. The BCN resistance of the monosomic additions (2n = 18 + 1) and the monosomic fragment additions (2n = 18 + f) is highly unstable whereas the resistance of the diploids appears to be more stable but also does not reach an acceptable level of stability (Lange et al. 1990; Van Geyt et al. 1990). Because of the difficulty to obtain stable resistant sugar beet varieties by traditional breeding, a program was started in april 1988 which aims at the isolation of BCN resistance gene(s) from wild beets of the section Procumbentes. The ultimate goals of this project are the transfer of the isolated resistance gene(s) to sugar beet to obtain stable resistant varieties and to elucidate the mode of action of the BCN resistance gene. Although, several groups are working on the isolation of genes conferring resistance to plant-parasitic nematodes, no such gene is isolated yet.
This thesis describes work aimed at the isolation of the BCN-resistance genes Hs1 pat-1 and Hs1 pro-1 via 'positional cloning' (Wicking and Williamsom 1991). 'Positional cloning' is a strategy for isolating genes which are only defined by their phenotype, a condition that holds for the BCN-resistance genes. For positional cloning the gene of interest is localized on the genome with respect to molecular markers. Next, flanking markers can be identified and used for the onset and termination of a chromosomal walk, which is the identification of a continuous set (contig) of overlapping DNA clones that connect the two flanking markers. A Yeast Artificial Chromosome (YAC) library (Burke et al. 1987, Ward & Jen 1990) that contains large cloned DNA-fragments of several hundred kilobases can aid the spanning of large chromosomal distances between the markers. Furthermore, the separation and manipulation of large chromosome fragments by Pulsed Field Gel Electrophoresis can be employed for the construction of a long-range physical map of the region. Finally, the essential chromosomal region, cloned in one or several contiguous YACs and subcloned in cosmids, is analyzed for the presence of candidate genes which are then screened for a functional BCN resistance gene.
Chapter 1 of this thesis describes morphological and genetic features of the plant-BCN interaction. This information is important for the ultimate development of nematode resistant plants. Furthermore, the positional cloning strategy for isolating genes is described in detail and the state of art for the identification and cloning of various nematodes resistance genes is given.
Chapter 2 describes the isolation of molecular markers linked to the BCN resistance locus, Hs1, which is the first prerequisite for positional cloning of the gene(s). The plant material which was used consisted of sugar beets with an introgressed wild beet chromosome fragment containing the resistance gene(s). Since the resistance in this material segregates in a nonMendelian way, a deletion mapping strategy was employed to order the markers with respect to the resistance locus.
Chapter 3 describes the characterization of a marker which is highly repetitive in wild beets and closely linked to Hs1 pat-1 and Hs1 pro-1 . The long-range physical organization of the repeat is studied by employing the PFGE-technology.
Chapter 4 describes the construction of a YAC-library from BCN-resistant sugar beet (AN5-203b) containing an additional fragment of a wild beet chromosome. This library was screened with a marker localized near the Hs1 pat-1 gene to provide a starting point for the assembly of a YAC- contig spanning the resistance locus.
Chapter 5 describes the isolation, characterization and deletion mapping of additional PCR-based RAPD markers.
In Chapter 6 physical distances around three markers linked to Hs1 pat-1 are determined which has resulted in a first generation physical map of the resistance locus.
Chapter 7 is a general discussion of the research which will be necessary for the ultimate positional cloning of the resistance genes. Furthermore, different strategies for the engineering of nematode resistant plants are discussed.
Towards isolation of the tomato root-knot nematode resistance gene MI via positional cloning
Daelen, R.A.J.J. van - \ 1995
Agricultural University. Promotor(en): A. van Kammen; W.J.T. Zabel. - S.l. : Van Daelen - ISBN 9789054853725 - 126
pratylenchus - heteroderidae - tylenchidae - moleculaire genetica - genetische modificatie - recombinant dna - pratylenchus - heteroderidae - tylenchidae - molecular genetics - genetic engineering - recombinant dna
Root-knot nematodes of the genus Meloidogyne are severe pathogens of plants and worldwide they cause damage to many economically important crops like potato, rice, cotton, and tomato. So the control of nematodes and the protection of plants against nematode damage are matters of major concern. Some plants carry resistance genes which prevent damage by nematodes. If these resistance genes would become available for introducing into other plant species, this could be of considerable economic importance. From a fundamental point of view, nematode resistance genes are also very interesting since they control the interaction between plants and parasites in a very specific manner. The Mi -gene of tomato is a single dominant gene, located on chromosome 6, that confers resistance against several species of root-knot nematodes and may serve as a model for the study of plant-nematode interactions. Such studies, to date, are severely hampered by a lack of knowledge of the proteins and the functions of the proteins encoded by the resistance genes. If the product of the gene is not known, the isolation of such a gene is very difficult. But nowadays several approaches have been developed to isolate genes that are only characterized by phenotype and genetic position. In chapter 1 an overview is presented of the different approaches, their relevance to the isolation of the nematode resistance gene Mi is evaluated.
The most relevant procedure for isolating the Mi -gene seemed to be positional cloning. This approach involves the identification of tightly linked molecular markers followed by a chromosomal walk which starts at these markers. The walk results in cloning of all sequences between two markers at either side of the gene. The gene itself can subsequently be identified from these sequences using the information encoded in the sequence. In order to proceed with the positonal cloning approach several technical requirements have to be met which were, at the onset of the present work, not available. The development and application of these new techniques is described in this thesis.
First of all, an efficient method for isolating and handling of megabase-sized plant DNA had to be developed, which is described in chapter 2. Furthermore, the technical means to electrophoretically separate large DNA fragments, by so called pulsed field gel electrophoresis, were becoming commercially available at the beginning of this work. In chapter 3, the application of these techniques to physically characterize large genomic regions and the construction of long range restriction maps for two Mi -flanking markers, GP79 and Aps-1 , are described. These maps provided the first physical characterization of parts of the Mi -region that was sofar only genetically characterized. The work described in this thesis has focused on Aps-1 and GP79 since those were the earliest available tightly linked markers. By now many other markers, not available at the onset of the work, are known.
The yeast artificial chromosome (YAC) cloning system allows for the cloning of fragments many hundred kb's in size. Such very large DNA fragments are an essential ingredient for chromosomal walking. The characteristics of YAC cloning are reviewed in chapter 4. For YAC cloning of plant DNA several technical adaptations were necessary, These were worked out in detail in the construction and characterization of a tomato Cla I YAC library, as described in chapter 5, and of a partial Eco RI YAC library, as described in chapter 6. Finally, in chapter 7, the lessons learned from the excercises described in the chapters 2, 3, 5 and 6 are evaluated, along with a discussion of how to proceed further now the techniques required for positional cloning the Mi -gene are available.