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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    Understanding plant immunity as a surveillance system to detect invasion
    Cook III, D.E. ; Mesarich, C.H. ; Thomma, B.P.H.J. - \ 2015
    Annual Review of Phytopathology 53 (2015). - ISSN 0066-4286 - p. 541 - 563.
    disease-resistance gene - bacterial elicitor flagellin - syringae effectors avrb - host-selective toxins - innate immunity - arabidopsis-thaliana - molecular-patterns - microbe interactions - durable resistance - necrotrophic pathogens
    Various conceptual models to describe the plant immune system have been presented. The most recent paradigm to gain wide acceptance in the field is often referred to as the zigzag model, which reconciles the previously formulated gene-for-gene hypothesis with the recognition of general elicitors in a single model. This review focuses on the limitations of the current paradigm of molecular plant-microbe interactions and how it too narrowly defines the plant immune system. As such, we discuss an alternative view of plant innate immunity as a system that evolves to detect invasion. This view accommodates the range from mutualistic to parasitic symbioses that plants form with diverse organisms, as well as the spectrum of ligands that the plant immune system perceives. Finally, how this view can contribute to the current practice of resistance breeding is discussed.
    DOG1-imposed dormancy mediates germination responses to temperature cues
    Murphey, M. ; Kovach, K. ; Elnacash, T. ; He, H. ; Bentsink, L. ; Donohue, K. - \ 2015
    Environmental and Experimental Botany 112 (2015). - ISSN 0098-8472 - p. 33 - 43.
    seed-maturation environment - quantitative trait locus - recent climate-change - arabidopsis-thaliana - life-history - ectopic expression - niche construction - natural-selection - dog1-like genes - dog1
    Seed dormancy and environment-dependent germination requirements interact to determine the timing of germination in natural environments. This study tested the contribution of the dormancy gene Delay Of Germination 1 (DOG1) to primary and secondary dormancy induction in response to environmental cues, and evaluated how DOG1-mediated dormancy influenced germination responses to different temperature cues. We verified that DOG1 is involved in the induction of primary dormancy in response to cool seed-maturation temperature experienced by maternal plants, and we found that it is also involved in secondary dormancy in response to warm and prolonged cold stratification experienced by seeds during imbibition. DOG1-imposed dormancy can also mediate germination responses to environmental conditions, including cold stratification and germination temperatures experienced by imbibing seeds. Specifically, germination responsiveness to temperature cues is most apparent when seeds exhibit an intermediate degree of dormancy. However, DOG1 itself does not seem to directly regulate the response to cold stratification nor does it determine the function of temperature-dependent germination, since DOG1 mutants were capable of exhibiting increased germination after cold stratification as well as temperature-dependent germination. Instead, DOG1 has major effects on germination behavior primarily by exposing or masking underlying environmental sensitivity, and thereby strongly influences how environmentally responsive germination can be, and when during a season, it is likely to exhibit environmental sensitivity.
    Organizer-Derived WOX5 Signal Maintains Root Columella Stem Cells through Chromatin-Mediated Repression of CDF4 Expression.
    Pi, L. ; Graaff, E. van der; Llavata Peris, C.I. ; Weijers, D. ; Henning, L. ; Groot, E. de; Laux, T. - \ 2015
    Developmental Cell 33 (2015)5. - ISSN 1534-5807 - p. 576 - 588.
    histone deacetylase - arabidopsis-thaliana - transcriptional repression - gene-expression - wuschel - meristem - shoot - topless - protein - fate
    Stem cells in plants and animals are maintained pluripotent by signals from adjacent niche cells. In plants, WUSCHEL HOMEOBOX (WOX) transcription factors are central regulators of stem cell maintenance in different meristem types, yet their molecular mode of action has remained elusive. Here we show that in the Arabidopsis root meristem, the WOX5 protein moves from the root niche organizer, the quiescent center, into the columella stem cells, where it directly represses the transcription factor gene CDF4. This creates a gradient of CDF4 transcription, which promotes differentiation opposite to the WOX5 gradient, allowing stem cell daughter cells to exit the stem cell state. We further show that WOX5 represses CDF4 transcription by recruiting TPL/TPR co-repressors and the histone deacetylase HDA19, which consequently induces histone deacetylation at the CDF4 regulatory region. Our results show that chromatin-mediated repression of differentiation programs is a common strategy in plant and animal stem cell niches.
    Large-Scale Phenomics Identifies Primary and Fine-Tuning Roles for CRKs in Responses Related to Oxidative Stress.
    Bourdais, G. ; Burdiak, P. ; Gauthier, A. ; Nitsch, L.M.C. ; Salojärvi, J. ; Rayapuram, C. ; Idänheimo, N. ; Hunter, K. ; Kimura, S. ; Merilo, E. ; Vaattovaara, A. ; Oracz, K. ; Kaufholdt, D. ; Pallon, A. ; Anggoro, D.T. ; Glów, D. ; Lowe, J. ; Zhou, J. ; Mohammadi, O. ; Puukko, T. ; Albert, A. ; Lang, H. ; Ernst, D. ; Kollist, H. ; Brosché, M. ; Durner, J. ; Borst, J.W. ; Collinge, D.B. ; Karpinski, S. ; Lyngkjær, M.F. ; Robatzek, S. ; Wrzaczek, M. ; Kangasjärvi, J. - \ 2015
    Plos Genetics 11 (2015)7. - ISSN 1553-7404
    receptor-like kinase - multiple sequence alignment - arabidopsis-thaliana - cell-death - protein-kinase - transcriptional regulation - pseudomonas-syringae - flagellin perception - light acclimation - stomatal immunity
    Cysteine-rich receptor-like kinases (CRKs) are transmembrane proteins characterized by the presence of two domains of unknown function 26 (DUF26) in their ectodomain. The CRKs form one of the largest groups of receptor-like protein kinases in plants, but their biological functions have so far remained largely uncharacterized. We conducted a large-scale phenotyping approach of a nearly complete crk T-DNA insertion line collection showing that CRKs control important aspects of plant development and stress adaptation in response to biotic and abiotic stimuli in a non-redundant fashion. In particular, the analysis of reactive oxygen species (ROS)-related stress responses, such as regulation of the stomatal aperture, suggests that CRKs participate in ROS/redox signalling and sensing. CRKs play general and fine-tuning roles in the regulation of stomatal closure induced by microbial and abiotic cues. Despite their great number and high similarity, large-scale phenotyping identified specific functions in diverse processes for many CRKs and indicated that CRK2 and CRK5 play predominant roles in growth regulation and stress adaptation, respectively. As a whole, the CRKs contribute to specificity in ROS signalling. Individual CRKs control distinct responses in an antagonistic fashion suggesting future potential for using CRKs in genetic approaches to improve plant performance and stress tolerance.
    Strigolactones, a Novel Carotenoid-Derived Plant Hormone
    Al-Babili, S. ; Bouwmeester, H.J. - \ 2015
    Annual Review of Plant Biology 66 (2015). - ISSN 1543-5008 - p. 161 - 186.
    arbuscular mycorrhizal symbiosis - low phosphorus availability - abscisic-acid biosynthesis - in-vitro characterization - cytochrome b(6)f complex - root-system architecture - tiller bud outgrowth - box protein max2 - germination stimulants - arabidopsis-thaliana
    Strigolactones (SLs) are carotenoid-derived plant hormones and signaling molecules. When released into the soil, SLs indicate the presence of a host to symbiotic fungi and root parasitic plants. In planta, they regulate several developmental processes that adapt plant architecture to nutrient availability. Highly branched/tillered mutants in Arabidopsis, pea, and rice have enabled the identification of four SL biosynthetic enzymes: a cis/trans-carotene isomerase, two carotenoid cleavage dioxygenases, and a cytochrome P450 (MAX1). In vitro and in vivo enzyme assays and analysis of mutants have shown that the pathway involves a combination of new reactions leading to carlactone, which is converted by a rice MAX1 homolog into an SL parent molecule with a tricyclic lactone moiety. In this review, we focus on SL biosynthesis, describe the hormonal and environmental factors that determine this process, and discuss SL transport and downstream signaling as well as the role of SLs in regulating plant development.
    Large-scale evolutionary analysis of genes and supergene clusters from terpenoid modular pathways provides insights into metabolic diversification in flowering plants.
    Hofberger, J.A. ; Ramirez, A.M. ; Bergh, E. van den; Zhu, X. ; Bouwmeester, H.J. ; Schuurink, R.C. ; Schranz, M.E. - \ 2015
    PLoS ONE 10 (2015)6. - ISSN 1932-6203 - 37 p.
    isopentenyl diphosphate isomerases - disease resistance genes - arabidopsis-thaliana - genome sequence - whole-genome - protein families - draft genome - isoprenoid biosynthesis - secondary metabolism - oxidosqualene cyclase
    An important component of plant evolution is the plethora of pathways producing more than 200,000 biochemically diverse specialized metabolites with pharmacological, nutritional and ecological significance. To unravel dynamics underlying metabolic diversification, it is critical to determine lineage-specific gene family expansion in a phylogenomics framework. However, robust functional annotation is often only available for core enzymes catalyzing committed reaction steps within few model systems. In a genome informatics approach, we extracted information from early-draft gene-space assemblies and non-redundant transcriptomes to identify protein families involved in isoprenoid biosynthesis. Isoprenoids comprise terpenoids with various roles in plant-environment interaction, such as pollinator attraction or pathogen defense. Combining lines of evidence provided by synteny, sequence homology and Hidden-Markov-Modelling, we screened 17 genomes including 12 major crops and found evidence for 1,904 proteins associated with terpenoid biosynthesis. Our terpenoid genes set contains evidence for 840 core terpene-synthases and 338 triterpene-specific synthases. We further identified 190 prenyltransferases, 39 isopentenyl-diphosphate isomerases as well as 278 and 219 proteins involved in mevalonate and methylerithrol pathways, respectively. Assessing the impact of gene and genome duplication to lineage-specific terpenoid pathway expansion, we illustrated key events underlying terpenoid metabolic diversification within 250 million years of flowering plant radiation. By quantifying Angiosperm-wide versatility and phylogenetic relationships of pleiotropic gene families in terpenoid modular pathways, our analysis offers significant insight into evolutionary dynamics underlying diversification of plant secondary metabolism. Furthermore, our data provide a blueprint for future efforts to identify and more rapidly clone terpenoid biosynthetic genes from any plant species.
    The epigenetic footprint of poleward range-expanding plants in apomictic dandelions
    Preite, V. ; Snoek, L.B. ; Oplaat, C. ; Biere, A. ; Putten, W.H. van der; Verhoeven, K.J.F. - \ 2015
    Molecular Ecology 24 (2015)17. - ISSN 0962-1083 - p. 4406 - 4418.
    dna methylation polymorphism - arabidopsis-thaliana - geographic parthenogenesis - ecological epigenetics - phenotypic plasticity - cytosine methylation - population-structure - japanese knotweed - common dandelion - taraxacum
    Epigenetic modifications, such as DNA methylation variation, can generate heritable phenotypic variation independent of the underlying genetic code. However, epigenetic variation in natural plant populations is poorly documented and little understood. Here, we test if northward range expansion of obligate apomicts of the common dandelion (Taraxacum officinale) is associated with DNA methylation variation. We characterized and compared patterns of genetic and DNA-methylation variation in greenhouse-reared offspring of T. officinale that were collected along a latitudinal transect of northward range expansion in Europe. Genetic AFLP and epigenetic MS-AFLP markers revealed high levels of local diversity and modest but significant heritable differentiation between sampling locations and between the Southern, Central and Northern regions of the transect. Patterns of genetic and epigenetic variation were significantly correlated, reflecting the genetic control over epigenetic variation and/or the accumulation of lineage-specific spontaneous epimutations, which may be selectively neutral. In addition, we identified a small component of DNA methylation differentiation along the transect that is independent of genetic variation. This epigenetic differentiation might reflect environment-specific induction or, in case the DNA methylation variation affects relevant traits and fitness, selection of heritable DNA methylation variants. Such generated epigenetic variants might contribute to the adaptive capacity of individual asexual lineages under changing environments. Our results highlight the potential of heritable DNA methylation variation to contribute to population differentiation along ecological gradients. Further studies are needed using higher-resolution methods to understand the functional significance of such natural occurring epigenetic differentiation.
    Genome-Wide Mapping of Structural Variations Reveals a Copy Number Variant That Determines Reproductive Morphology in Cucumber
    Zhang, Z. ; Mao, L. ; Chen, Junshi ; Bu, F. ; Li, G. ; Sun, J. ; Li, S. ; Sun, H. ; Jiao, C. ; Blakely, R. ; Pan, J. ; Cai, R. ; Luo, R. ; Peer, Y. Van de; Jacobsen, E. ; Fei, Z. ; Huang, S. - \ 2015
    The Plant Cell 27 (2015)6. - ISSN 1040-4651 - p. 1595 - 1604.
    indel-associated mutation - tuberculate fruit gene - false discovery rate - arabidopsis-thaliana - population-scale - functional impact - sequencing data - synthase gene - paired-end - sativus l.
    Structural variations (SVs) represent a major source of genetic diversity. However, the functional impact and formation mechanisms of SVs in plant genomes remain largely unexplored. Here, we report a nucleotide-resolution SV map of cucumber (Cucumis sativas) that comprises 26,788 SVs based on deep resequencing of 115 diverse accessions. The largest proportion of cucumber SVs was formed through nonhomologous end-joining rearrangements, and the occurrence of SVs is closely associated with regions of high nucleotide diversity. These SVs affect the coding regions of 1676 genes, some of which are associated with cucumber domestication. Based on the map, we discovered a copy number variation (CNV) involving four genes that defines the Female (F) locus and gives rise to gynoecious cucumber plants, which bear only female flowers and set fruit at almost every node. The CNV arose from a recent 30.2-kb duplication at a meiotically unstable region, likely via microhomology-mediated break-induced replication. The SV set provides a snapshot of structural variations in plants and will serve as an important resource for exploring genes underlying key traits and for facilitating practical breeding in cucumber.
    Immune activation mediated by the late blight resistance protein R1 requires nuclear localization of R1 and AVR1
    Du, Y. ; Berg, J. ; Govers, F. ; Bouwmeester, K. - \ 2015
    New Phytologist 207 (2015)3. - ISSN 0028-646X - p. 735 - 747.
    disease-resistance - phytophthora-infestans - arabidopsis-thaliana - innate immunity - plant immunity - receptor - recognition - potato - gene - component
    Resistance against oomycete pathogens is mainly governed by intracellular nucleotide-binding leucine-rich repeat (NLR) receptors that recognize matching avirulence (AVR) proteins from the pathogen, RXLR effectors that are delivered inside host cells. Detailed molecular understanding of how and where NLR proteins and RXLR effectors interact is essential to inform the deployment of durable resistance (R) genes. Fluorescent tags, nuclear localization signals (NLSs) and nuclear export signals (NESs) were exploited to determine the subcellular localization of the potato late blight protein R1 and the Phytophthora infestans RXLR effector AVR1, and to target these proteins to the nucleus or cytoplasm. Microscopic imaging revealed that both R1 and AVR1 occurred in the nucleus and cytoplasm, and were in close proximity. Transient expression of NLS- or NES-tagged R1 and AVR1 in Nicotiana benthamiana showed that activation of the R1-mediated hypersensitive response and resistance required localization of the R1/AVR1 pair in the nucleus. However, AVR1-mediated suppression of cell death in the absence of R1 was dependent on localization of AVR1 in the cytoplasm. Balanced nucleocytoplasmic partitioning of AVR1 seems to be a prerequisite. Our results show that R1-mediated immunity is activated inside the nucleus with AVR1 in close proximity and suggest that nucleocytoplasmic transport of R1 and AVR1 is tightly regulated.
    Remarkably divergent regions punctuate the genome assembly of the Caenorhabditis elegans Hawaiian strain CB4856
    Thompson, O.A. ; Snoek, L.B. ; Nijveen, H. ; Sterken, M.G. ; Volkers, R.J.M. ; Brenchley, R. ; Hof, A. van 't; Bevers, R.P.J. ; Cossins, A.R. ; Yanai, I. ; Hajnal, A. ; Schmid, T. ; Perkins, J.D. ; Spencer, D. ; Kruglyak, L. ; Andersen, E.C. ; Moerman, D.G. ; Hillier, L.W. ; Kammenga, J.E. ; Waterston, R.H. - \ 2015
    Genetics 200 (2015)3. - ISSN 0016-6731 - p. 975 - 989.
    natural variation data - c. elegans - arabidopsis-thaliana - gene - polymorphism - populations - diversity - nematodes - dna - evolutionary
    The Hawaiian strain (CB4856) of Caenorhabditis elegans is one of the most divergent from the canonical laboratory strain N2 and has been widely used in developmental, population and evolutionary studies. To enhance the utility of the strain, we have generated a draft sequence of the CB4856 genome, exploiting a variety of resources and strategies. The CB4856 genome when compared against the N2 reference has 327,050 single nucleotide variants (SNVs) and 79,529 insertion-deletion events (indels) that result in a total of 3.3 megabasepairs (Mb) of N2 sequence missing from CB4856 and 1.4 Mb of sequence present in CB4856 not present in N2. As previously reported, the density of SNVs varies along the chromosomes, with the arms of chromosomes showing greater average variation than the centers. In addition, we find 61 regions totaling 2.8 Mb, distributed across all six chromosomes, that have a greatly elevated SNV density, ranging from 2% to 16% SNVs. A survey of other wild isolates show that the two alternative haplotypes for each region are widely distributed, suggesting they have been maintained by balancing selection over long evolutionary times. These divergent regions contain an abundance of genes from large rapidly evolving families encoding F-box, MATH, BATH, seven-transmembrane G-coupled receptors, and nuclear hormone receptors suggesting that they provide selective advantages in natural environments. The draft sequence makes available a comprehensive catalog of sequence differences between the CB4856 and N2 strains that will facilitate the molecular dissection of their phenotypic differences. Our work also emphasizes the importance of going beyond simple alignment of reads to a reference genome when assessing differences between genomes.
    Variation in plant-mediated interactions between rhizobacteria and caterpillars: potential role of soil composition
    Pangesti, N.P.D. ; Pineda Gomez, A.M. ; Dicke, M. ; Loon, J.J.A. van - \ 2015
    Plant Biology 17 (2015)2. - ISSN 1435-8603 - p. 474 - 483.
    induced systemic resistance - arbuscular mycorrhizal symbiosis - arabidopsis-thaliana - insect herbivores - gene-expression - jasmonic acid - pseudomonas-fluorescens - microbes - bacteria - immunity
    Selected strains of non-pathogenic rhizobacteria can trigger induced systemic resistance (ISR) in plants against aboveground insect herbivores. However, the underlying mechanisms of plant-mediated interactions between rhizobacteria and herbivorous insects are still poorly understood. Using Arabidopsis thaliana Col-0-Pseudomonas fluorescens WCS417r as a model system, we investigated the performance and the molecular mechanisms underlying plant-mediated effects of rhizobacteria on the generalist caterpillar Mamestra brassicae and the specialist Pieris brassicae. Rhizobacteria colonisation of Arabidopsis roots resulted in decreased larval weight of M. brassicae, whereas no effect was observed on larval weight of P. brassicae. Using a jasmonic acid (JA)-impaired mutant (dde2-2), we confirmed the importance of JA in rhizobacteria-mediated ISR against M. brassicae. Interestingly, in some experiments we also observed rhizobacteria-induced systemic susceptibility to M. brassicae. The role of soil composition in the variable outcomes of microbe-plant-insect interactions was then assessed by comparing M. brassicae performance and gene transcription in plants grown in potting soil or a mixture of potting soil and sand in a 1:1 ratio. In a mixture of potting soil and sand, rhizobacteria treatment had a consistent negative effect on M. brassicae, whereas the effect was more variable in potting soil. Interestingly, at 24 h post-infestation (hpi) rhizobacteria treatment primed plants grown in a mixture of potting soil and sand for stronger expression of the JA- and ethylene-regulated genes PDF1.2 and HEL, respectively. Our study shows that soil composition can modulate rhizobacteria-plant-insect interactions, and is a factor that should be considered when studying these belowground-aboveground interactions.
    Genetic basis and detection of unintended effects in genetically modified crop plants
    Ladics, G.S. ; Bartholomaeus, A. ; Bregitzer, P. ; Doerrer, N.G. ; Gray, A. ; Holzhauzer, T. ; Jordan, M. ; Keese, P. ; Kok, E.J. ; Macdonald, P. ; Parrott, W. ; Privalle, L. ; Raybould, A. ; Rhee, S.Y. ; Rice, E. ; Romeis, J. ; Vaughn, J. ; Wal, J.M. ; Glenn, K. - \ 2015
    Transgenic Research 24 (2015)4. - ISSN 0962-8819 - p. 587 - 603.
    weed risk-assessment - biochemical pathway database - engineered breeding stacks - multiple fungal pathogens - metabolic flux analysis - somaclonal variation - safety assessment - intellectual disability - arabidopsis-thaliana - transgenic barley
    In January 2014, an international meeting sponsored by the International Life Sciences Institute/Health and Environmental Sciences Institute and the Canadian Food Inspection Agency titled “Genetic Basis of Unintended Effects in Modified Plants” was held in Ottawa, Canada, bringing together over 75 scientists from academia, government, and the agro-biotech industry. The objectives of the meeting were to explore current knowledge and identify areas requiring further study on unintended effects in plants and to discuss how this information can inform and improve genetically modified (GM) crop risk assessments. The meeting featured presentations on the molecular basis of plant genome variability in general, unintended changes at the molecular and phenotypic levels, and the development and use of hypothesis-driven evaluations of unintended effects in assessing conventional and GM crops. The development and role of emerging “omics” technologies in the assessment of unintended effects was also discussed. Several themes recurred in a number of talks; for example, a common observation was that no system for genetic modification, including conventional methods of plant breeding, is without unintended effects. Another common observation was that “unintended” does not necessarily mean “harmful”. This paper summarizes key points from the information presented at the meeting to provide readers with current viewpoints on these topics.
    A complex interplay of tandem- and whole genome duplication drives expansion of the L-type lectin receptor kinase gene family in the brassicaceae
    Hofberger, J.A. ; Nsibo, D.L. ; Govers, F. ; Bouwmeester, K. ; Schranz, M.E. - \ 2015
    Genome Biology and Evolution 7 (2015)3. - ISSN 1759-6653 - p. 720 - 734.
    disease resistance genes - arabidopsis-thaliana - phylogenetic analysis - triggered immunity - provides insight - wide analysis - evolution - plants - diversification - expression
    The comparative analysis of plant gene families in a phylogenetic framework has greatly accelerated due to advances in next generation sequencing. In this study, we provide an evolutionary analysis of the L-type lectin receptor kinase and L-type lectin domain proteins (L-type LecRKs and LLPs) that are considered as components in plant immunity, in the plant family Brassicaceae and related outgroups. We combine several lines of evidence provided by sequence homology, HMM-driven protein domain annotation, phylogenetic analysis and gene synteny for large-scale identification of L-type LecRK and LLP genes within nine core-eudicot genomes. We show that both polyploidy and local duplication events (tandem duplication and gene transposition duplication) have played a major role in L-type LecRK and LLP gene family expansion in the Brassicaceae. We also find significant differences in rates of molecular evolution based on the mode of duplication. Additionally, we show that LLPs share a common evolutionary origin with L-type LecRKs and provide a consistent gene family nomenclature. Finally, we demonstrate that the largest and most diverse L-type LecRK clades are lineage-specific. Our evolutionary analyses of these plant immune components provide a framework to support future plant resistance breeding.
    Isolation and identification of 4-a-rhamnosyloxy benzyl glucosinolate in Noccaea caerulescens showing intraspecific variation
    Graaf, R.M. de; Krosse, S. ; Swolfs, A.E.M. ; Brinke, E. te; Prill, N. ; Leimu, R. ; Galen, P.M. van; Wang, Y. ; Aarts, M.G.M. ; Dam, N.M. van - \ 2015
    Phytochemistry 110 (2015). - ISSN 0031-9422 - p. 166 - 171.
    hyperaccumulator thlaspi-praecox - moringa-oleifera l. - mustard oil bomb - arabidopsis-thaliana - plants - isothiocyanates - stenopetala - accumulation - brassicaceae - profiles
    Glucosinolates are secondary plant compounds typically found in members of the Brassicaceae and a few other plant families. Usually each plant species contains a specific subset of the ~130 different glucosinolates identified to date. However, intraspecific variation in glucosinolate profiles is commonly found. Sinalbin (4-hydroxybenzyl glucosinolate) so far has been identified as the main glucosinolate of the heavy metal accumulating plant species Noccaea caerulescens (Brassicaceae). However, a screening of 13 N. caerulescens populations revealed that in 10 populations a structurally related glucosinolate was found as the major component. Based on nuclear magnetic resonance (NMR) and mass spectrometry analyses of the intact glucosinolate as well as of the products formed after enzymatic conversion by sulfatase or myrosinase, this compound was identified as 4-a-rhamnosyloxy benzyl glucosinolate (glucomoringin). So far, glucomoringin had only been reported as the main glucosinolate of Moringa spp. (Moringaceae) which are tropical tree species. There was no apparent relation between the level of soil pollution at the location of origin, and the presence of glucomoringin. The isothiocyanate that is formed after conversion of glucomoringin is a potent antimicrobial and antitumor agent. It has yet to be established whether glucomoringin or its breakdown product have an added benefit to the plant in its natural habitat
    AIL and HDG proteins act antagonistically to control cell proliferation
    Horstman, A. ; Fukuoka, H. ; Muino Acuna, J.M. ; Nitsch, L.M.C. ; Guo, Changhao ; Passarinho, P.A. ; Sanchez Perez, G.F. ; Immink, R.G.H. ; Angenent, G.C. ; Boutilier, K.A. - \ 2015
    Development 142 (2015). - ISSN 0950-1991 - p. 454 - 464.
    arabidopsis-thaliana - transcription factors - plant transformation - ectopic expression - quantitative pcr - chip-seq - differentiation - genes - plethora - growth
    AINTEGUMENTA-LIKE (AIL) transcription factors are key regulators of cell proliferation and meristem identity. Although AIL functions have been well described, the direct signalling components of this pathway are largely unknown.We show that BABY BOOM(BBM) and other AIL proteins physically interact with multiple members of the L1-expressed HOMEODOMAIN GLABROUS (HDG) transcription factor family, including HDG1, HDG11 and HDG12. Overexpression of HDG1, HDG11 and HDG12 restricts growth due to root and shoot meristem arrest, which is associated with reduced expression of genes involved in meristem development and cell proliferation pathways, whereas downregulation of multiple HDG genes promotes cell overproliferation. These results suggest a role for HDG proteins in promoting cell differentiation. We also reveal a transcriptional network in which BBM andHDG1regulate several common target genes, and whereBBM/AIL and HDG regulate the expression of each other. Taken together, these results suggest opposite roles for AIL and HDG proteins, with AILs promoting cell proliferation and HDGs stimulating cell differentiation, and that these functions are mediated at both the protein-protein interaction and transcriptional level.
    Marker-Based Estimation of Heritability in Immortal Populations
    Kruijer, W.T. ; Boer, M.P. ; Malosetti, M. ; Flood, P.J. ; Engel, B. ; Kooke, R. ; Keurentjes, J.J.B. ; Eeuwijk, F.A. van - \ 2015
    Genetics 199 (2015)2. - ISSN 0016-6731 - p. 379 - 398.
    genome-wide association - multi-environment trials - quantitative trait loci - plant-breeding trials - linear mixed models - arabidopsis-thaliana - missing heritability - complex traits - selection - prediction
    Heritability is a central parameter in quantitative genetics, both from an evolutionary and a breeding perspective. For plant traits heritability is traditionally estimated by comparing within and between genotype variability. This approach estimates broad-sense heritability, and does not account for different genetic relatedness. With the availability of high-density markers there is growing interest in marker based estimates of narrow-sense heritability, using mixed models in which genetic relatedness is estimated from genetic markers. Such estimates have received much attention in human genetics but are rarely reported for plant traits. A major obstacle is that current methodology and software assume a single phenotypic value per genotype, hence requiring genotypic means. An alternative that we propose here, is to use mixed models at individual plant or plot level. Using statistical arguments, simulations and real data we investigate the feasibility of both approaches, and how these affect genomic prediction with G-BLUP and genome-wide association studies. Heritability estimates obtained from genotypic means had very large standard errors and were sometimes biologically unrealistic. Mixed models at individual plant or plot level produced more realistic estimates, and for simulated traits standard errors were up to 13 times smaller. Genomic prediction was also improved by using these mixed models, with up to a 49% increase in accuracy. For GWAS on simulated traits, the use of individual plant data gave almost no increase in power. The new methodology is applicable to any complex trait where multiple replicates of individual genotypes can be scored. This includes important agronomic crops, as well as bacteria and fungi.
    Fruit illumination stimulates cell division but has no detectable effect on fruit size in tomato (Solanum lycopersicum)
    Okello, R.C. ; Heuvelink, E. ; Visser, P.H.B. de; Lammers, M. ; Maagd, R.A. de; Marcelis, L.F.M. ; Struik, P.C. - \ 2015
    Physiologia Plantarum 154 (2015)1. - ISSN 0031-9317 - p. 114 - 127.
    arabidopsis-thaliana - elongation growth - plant development - seed development - sink metabolism - cucumber fruits - gene-expression - hormone-levels - abscisic-acid - phytochrome-b
    Light affects plant growth through assimilate availability and signals regulating development. The effects of light on growth of tomato fruit were studied using cuvettes with light-emitting diodes providing white, red or blue light to individual tomato trusses for different periods during daytime. Hypotheses tested were as follows: (1) light-grown fruits have stronger assimilate sinks than dark-grown fruits, and (2) responses depend on light treatment provided, and fruit development stage. Seven light treatments [dark, 12-h white, 24-h white, 24-h red and 24-h blue light, dark in the first 24 days after anthesis (DAA) followed by 24-h white light until breaker stage, and its reverse] were applied. Observations were made between anthesis and breaker stage at fruit, cell and gene levels. Fruit size and carbohydrate content did not respond to light treatments while cell division was strongly stimulated at the expense of cell expansion by light. The effects of light on cell number and volume were independent of the combination of light color and intensity. Increased cell division and decreased cell volume when fruits were grown in the presence of light were not clearly corroborated by the expression pattern of promoters and inhibitors of cell division and expansion analyzed in this study, implying a strong effect of posttranscriptional regulation. Results suggest the existence of a complex homeostatic regulatory system for fruit growth in which reduced cell division is compensated by enhanced cell expansion.
    The Top 10 oomycete pathogens in molecular plant pathology
    Kamoun, S. ; Furzer, O. ; Jones, J.D.G. ; Judelson, H.S. ; Ali, G.S. ; Dalio, R.J.D. ; Roy, S.G. ; Schena, L. ; Zambounis, A. ; Panabières, F. ; Cahill, D. ; Ruocco, M. ; Figueiredo, A. ; Chen, X.R. ; Hulvey, J. ; Stam, R. ; Lamour, K. ; Gijzen, M. ; Tyler, B.M. ; Grünwald, N.J. ; Mukhtar, M.S. ; Tomé, D.F.A. ; Tör, M. ; Ackerveken, G. van den; McDowell, J. ; Daayf, F. ; Fry, W.E. ; Lindqvist-Kreuze, H. ; Meijer, H.J.G. ; Petre, B. ; Ristaino, J. ; Yoshida, K. ; Birch, P.R.J. ; Govers, F. - \ 2015
    Molecular Plant Pathology 16 (2015)4. - ISSN 1464-6722 - p. 413 - 434.
    grapevine downy mildew - irish potato famine - sudden oak death - blister rusts albuginaceae - eastern united-states - 3 clonal lineages - nb-lrr gene - phytophthora-infestans - plasmopara-viticola - arabidopsis-thaliana
    Oomycetes form a deep lineage of eukaryotic organisms that includes a large number of plant pathogens that threaten natural and managed ecosystems. We undertook a survey to query the community for their ranking of plant pathogenic oomycete species based on scientific and economic importance. In total, we received 263 votes from 62 scientists in 15 countries for a total of 33 species. The Top 10 species and their ranking are: (1) Phytophthora infestans; (2, tied) Hyaloperonospora arabidopsidis; (2, tied) Phytophthora ramorum; (4) Phytophthora sojae; (5) Phytophthora capsici; (6) Plasmopara viticola; (7) Phytophthora cinnamomi; (8, tied) Phytophthora parasitica; (8, tied) Pythium ultimum; and (10) Albugo candida. The article provides an introduction to these 10 taxa and a snapshot of current research. We hope that the list will serve as a benchmark for future trends in oomycete research.
    On selection for flowering time plasticity in response to density
    Vermeulen, P.J. - \ 2015
    New Phytologist 205 (2015)1. - ISSN 0028-646X - p. 429 - 439.
    arabidopsis-thaliana - phenotypic plasticity - shade-avoidance - adaptive plasticity - impatiens-capensis - dependent selection - plant-populations - genetic-variation - local adaptation - life-history
    Different genotypes often exhibit opposite plastic responses in the timing of the onset of flowering with increasing plant density. In experimental studies, selection for accelerated flowering is generally found. By contrast, game theoretical studies predict that there should be selection for delayed flowering when competition increases. Combining different optimality criteria, the conditions under which accelerated or delayed flowering in response to density would be selected for are analysed with a logistic growth simulation model. To maximize seed production at the whole-stand level (simple optimization), selection should lead to accelerated flowering at high plant density, unless very short growing seasons select for similar onset of flowering at all densities. By contrast, selection of relative individual fitness will lead to delayed flowering when season length is long and/or growth rates are high. These different results give a potential explanation for the observed differences in direction of the plastic responses within and between species, including homeostasis, as a result of the effect of the variation in season length on the benefits of delayed flowering. This suggests that limited plasticity can evolve without the costs and limits that are currently thought to constrain the evolution of plasticity.
    The Cellulase KORRIGAN Is Part of the Cellulose Synthase Complex
    Vain, T. ; Crowell, E.F. ; Timpano, H. ; Biot, E. ; Desprez, T. ; Mansoori Zangir, N. ; Trindade, L.M. ; Pagant, S. ; Robert, S. ; Hofte, H. ; Gonneau, M. ; Vernhettes, S. - \ 2014
    Plant Physiology 165 (2014)4. - ISSN 0032-0889 - p. 1521 - 1532.
    secondary cell-wall - arabidopsis-thaliana - genetic-evidence - plasma-membrane - higher-plants - endo-1,4-beta-glucanase - microtubules - trafficking - elongation - endo-1,4-beta-d-glucanase
    Plant growth and organ formation depend on the oriented deposition of load-bearing cellulose microfibrils in the cell wall. Cellulose is synthesized by a large relative molecular weight cellulose synthase complex (CSC), which comprises at least three distinct cellulose synthases. Cellulose synthesis in plants or bacteria also requires the activity of an endo-1,4-beta-D-glucanase, the exact function of which in the synthesis process is not known. Here, we show, to our knowledge for the first time, that a leaky mutation in the Arabidopsis (Arabidopsis thaliana) membrane-bound endo-1,4-beta-D-glucanase KORRIGAN1 (KOR1) not only caused reduced CSC movement in the plasma membrane but also a reduced cellulose synthesis inhibitor-induced accumulation of CSCs in intracellular compartments. This suggests a role for KOR1 both in the synthesis of cellulose microfibrils and in the intracellular trafficking of CSCs. Next, we used a multidisciplinary approach, including live cell imaging, gel filtration chromatography analysis, split ubiquitin assays in yeast (Saccharomyces cerevisiae NMY51), and bimolecular fluorescence complementation, to show that, in contrast to previous observations, KOR1 is an integral part of the primary cell wall CSC in the plasma membrane.
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