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.

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Evolution of Hyaloperonospora effectors: ATR1 effector homologs from sister species of the downy mildew pathogen H. arabidopsidis are not recognised by RPP1WsB
Solovyeva, I. ; Schmuker, A. ; Cano, L.M. ; Damme, M. van; Ploch, S. ; Kamoun, S. ; Thines, M. - \ 2015
Mycological Progress 14 (2015). - ISSN 1617-416X - 9 p.
plant immune-system - phylogenetic-relationships - peronospora-parasitica - oomycete effector - resistance gene - proteins - sequences - thaliana - reveals - plasmopara
Like other plant-pathogenic oomycetes, downy mildew species of the genus Hyaloperonospora manipulate their hosts by secreting effector proteins. Despite intense research efforts devoted to deciphering the virulence and avirulence activities of effectors in the H. arabidopsidis/Arabidopsis thaliana pathosystem, there is only a single study in this pathosystem on the variation of effectors and resistance genes in natural populations, and the evolution of these effectors in the context of pathogen evolution is studied even less. In this work, the identification of A rabidopsis t haliana recognised (ATR)1-homologs is reported in two sister species of H. arabidopsidis, H. thlaspeos-perfoliati, and H. crispula, which are specialized on the host plants Microthlaspi perfoliatum and Reseda lutea, respectively. ATR1-diversity within these sister species of H. arabidopsidis was evaluated, and the ATR1-homologs from different isolates of H. thlaspeos-perfoliati and H. crispula were tested to see if they would be recognised by the previously characterised RPP1-WsB protein from A. thaliana. None of the effectors from the sister species was recognised, suggesting that due to the adaptation to altered or new targets after a host jump, features of variable effectors might vary to a degree that recognition of orthologous Avr-causing effectors is no longer effective and probably does not contribute to non-host immunity.
A plant U-box protein, PUB4, regulates asymmetric cell division and cell proliferation in the root meristem
Kinoshita, A. ; Hove, C.A. ten; Tabata, R. ; Yamada, M. ; Shimizu, N. ; Ishida, T. ; Yamaguchi, K. ; Shigenobu, S. ; Takebayashi, Y. ; Luchies, J. ; Kobayashi, M. ; Kurata, T. ; Wada, T. ; Seo, M. ; Hasebe, M. ; Blilou, I. ; Fukuda, H. ; Scheres, B. ; Heidstra, R. ; Kamiya, Y. ; Sawa, S. - \ 2015
Development 142 (2015). - ISSN 0950-1991 - p. 444 - 453.
receptor-like kinase - arabidopsis shoot meristem - of-function phenotypes - cle peptides - gene-expression - repeat protein - differentiation - thaliana - organization - growth
The root meristem (RM) is a fundamental structure that is responsible for postembryonic root growth. The RM contains the quiescent center (QC), stem cells and frequently dividing meristematic cells, in which the timing and the frequency of cell division are tightly regulated. In Arabidopsis thaliana, several gain-of-function analyses have demonstrated that peptide ligands of the CLAVATA3 (CLV3)/EMBRYO SURROUNDING REGION-RELATED (CLE) family are important for maintaining RM size. Here, we demonstrate that a plant U-box E3 ubiquitin ligase, PUB4, is a novel downstream component of CLV3/CLE signaling in the RM. Mutations in PUB4 reduced the inhibitory effect of exogenous CLV3/CLE peptide on root cell proliferation and columella stem cell maintenance. Moreover, pub4 mutants grown without exogenous CLV3/CLE peptide exhibited characteristic phenotypes in the RM, such as enhanced root growth, increased number of cortex/endodermis stem cells and decreased number of columella layers. Our phenotypic and gene expression analyses indicated that PUB4 promotes expression of a cell cycle regulatory gene, CYCD6;1, and regulates formative periclinal asymmetric cell divisions in endodermis and cortex/endodermis initial daughters. These data suggest that PUB4 functions as a global regulator of cell proliferation and the timing of asymmetric cell division that are important for final root architecture.
A Quantitative and Dynamic Model of the Arabidopsis Flowering Time Gene Regulatory Network
Valentim, F.L. ; Mourik, S. van; Posé, D. ; Kim, M.C. ; Schmid, M. ; Ham, R.C.H.J. van; Busscher, M. ; Sanchez Perez, G.F. ; Molenaar, J. ; Angenent, G.C. ; Immink, R.G.H. ; Dijk, A.D.J. van - \ 2015
PLoS ONE 10 (2015)2. - ISSN 1932-6203
floral transition - feedback loops - ft protein - expression - induction - transport - thaliana - signals - leafy - soc1
Various environmental signals integrate into a network of floral regulatory genes leading to the final decision on when to flower. Although a wealth of qualitative knowledge is available on how flowering time genes regulate each other, only a few studies incorporated this knowledge into predictive models. Such models are invaluable as they enable to investigate how various types of inputs are combined to give a quantitative readout. To investigate the effect of gene expression disturbances on flowering time, we developed a dynamic model for the regulation of flowering time in Arabidopsis thaliana. Model parameters were estimated based on expression time-courses for relevant genes, and a consistent set of flowering times for plants of various genetic backgrounds. Validation was performed by predicting changes in expression level in mutant backgrounds and comparing these predictions with independent expression data, and by comparison of predicted and experimental flowering times for several double mutants. Remarkably, the model predicts that a disturbance in a particular gene has not necessarily the largest impact on directly connected genes. For example, the model predicts that SUPPRESSOR OF OVEREXPRESSION OF CONSTANS (SOC1) mutation has a larger impact on APETALA1 (AP1), which is not directly regulated by SOC1, compared to its effect on LEAFY (LFY) which is under direct control of SOC1. This was confirmed by expression data. Another model prediction involves the importance of cooperativity in the regulation of APETALA1 (AP1) by LFY, a prediction supported by experimental evidence. Concluding, our model for flowering time gene regulation enables to address how different quantitative inputs are combined into one quantitative output, flowering time.
Introgression Browser: High throughput whole-genome SNP visualization
Aflitos, S.A. ; Sanchez Perez, G.F. ; Ridder, D. de; Fransz, P. ; Schranz, M.E. ; Jong, J.H.S.G.M. de; Peters, S.A. - \ 2015
The Plant Journal 82 (2015)1. - ISSN 0960-7412 - p. 174 - 182.
in-situ hybridization - alien chromosomes - recombination - tomato - markers - thaliana - potato - identification - organization - improvement
Breeding by introgressive hybridization is a pivotal strategy to broaden the genetic basis of crops. Usually, the desired traits are monitored in consecutive crossing generations by marker-assisted selection, but their analyses fail in chromosome regions where crossover recombinants are rare or not viable. Here, we present the Introgression Browser (IBROWSER), a bioinformatics tool aimed at visualizing introgressions at nucleotide or SNP accuracy. The software selects homozygous SNPs from Variant Call Format (VCF) information and filters out heterozygous SNPs, Multi-Nucleotide Polymorphisms (MNPs) and insertion-deletions (InDels). For data analysis IBROWSER makes use of sliding windows, but if needed it can generate any desired fragmentation pattern through General Feature Format (GFF) information. In an example of tomato (Solanum lycopersicum) accessions we visualize SNP patterns and elucidate both position and boundaries of the introgressions. We also show that our tool is capable of identifying alien DNA in a panel of the closely related S. pimpinellifolium by examining phylogenetic relationships of the introgressed segments in tomato. In a third example, we demonstrate the power of the IBROWSER in a panel of 597 Arabidopsis accessions, detecting the boundaries of a SNP-free region around a polymorphic 1.17 Mbp inverted segment on the short arm of chromosome 4. The architecture and functionality of IBROWSER makes the software appropriate for a broad set of analyses including SNP mining, genome structure analysis, and pedigree analysis. Its functionality, together with the capability to process large data sets and efficient visualization of sequence variation, makes IBROWSER a valuable breeding tool.
Reduced seed germination in Arabidopsis over-expressing SWI/SNF2 ATPase genes
Leeggangers, H.A.C.F. ; Folta, A. ; Muras, A. ; Nap, J.P.H. ; Mlynarova, L. - \ 2015
Physiologia Plantarum 153 (2015)2. - ISSN 0031-9317 - p. 318 - 326.
thaliana - dormancy - transcription - maturation - stress - arrest - growth - rna
In the life of flowering plants, seed germination is a critical step to ensure survival into the next generation. Generally the seed prior to germination has been in a dormant state with a low rate of metabolism. In the transition from a dormant seed to a germinating seed, various epigenetic mechanisms play a regulatory role. Here, we demonstrate that the over-expression of chromatin remodeling ATPase genes (AtCHR12 or AtCHR23) reduced the frequency of seed germination in Arabidopsis thaliana up to 30% relative to the wild-type seeds. On the other hand, single loss-of-function mutations of the two genes did not affect seed germination. The reduction of germination in over-expressing mutants was more pronounced in stress conditions (salt or high temperature), showing the impact of the environment. Reduced germinations upon over-expression coincided with increased transcript levels of seed maturation genes and with reduced degradation of their mRNAs stored in dry seeds. Our results indicate that repression of AtCHR12/23 gene expression in germinating wild-type Arabidopsis seeds is required for full germination. This establishes a functional link between chromatin modifiers and regulatory networks towards seed maturation and germination.
Nicotianamine Secretion for Zinc Excess Tolerance
Aarts, M.G.M. - \ 2014
Plant Physiology 166 (2014)2. - ISSN 0032-0889 - p. 751 - 752.
arabidopsis-halleri - metal hyperaccumulation - noccaea-caerulescens - roots - expression - thaliana - genes
Plants acquire micronutrients such as iron (Fe), zinc (Zn), manganese, or copper from soil. These micronutrients are often not readily available and they need to be mobilized to the proper free ionic form in order to be taken up by plant roots. Perhaps the only exception to this is the uptake of Fe by grasses, which have evolved a so-called strategy II uptake mechanism that involves the secretion of mugineic acid (MA)-family phytosiderophores to chelate Fe(III). These plants then take up the chelated Fe(III)-siderophore complexes. Most other plant species use strategy I for Fe uptake, which depends on the reduction of Fe(III) to Fe(II) and uptake through Fe2+ transporters. Because strategy II is less pH dependent than strategy I, it offers an evolutionary advance to grasses, especially when grown on calcareous soils (Römheld and Marschner, 1986).
REDUCED DORMANCY5 Encodes a Protein Phosphatase 2C That Is Required for Seed Dormancy in Arabidopsis
Xiang, Y. ; Nakabayashi, K. ; Ding, J. ; He, F. ; Bentsink, L. ; Soppe, W.J.J. - \ 2014
The Plant Cell 26 (2014)11. - ISSN 1040-4651 - p. 4362 - 4375.
rna-binding proteins - abscisic-acid - messenger-rna - pp2c phosphatases - germination - thaliana - aba - reveals - gene - mutants
Seed dormancy determines germination timing and contributes to crop production and the adaptation of natural populations to their environment. Our knowledge about its regulation is limited. In a mutagenesis screen of a highly dormant Arabidopsis thaliana line, the reduced dormancy5 (rdo5) mutant was isolated based on its strongly reduced seed dormancy. Cloning of RDO5 showed that it encodes a PP2C phosphatase. Several PP2C phosphatases belonging to clade A are involved in abscisic acid signaling and control seed dormancy. However, RDO5 does not cluster with clade A phosphatases, and abscisic acid levels and sensitivity are unaltered in the rdo5 mutant. RDO5 transcript could only be detected in seeds and was most abundant in dry seeds. RDO5 was found in cells throughout the embryo and is located in the nucleus. A transcriptome analysis revealed that several genes belonging to the conserved PUF family of RNA binding proteins, in particular Arabidopsis PUMILIO9 (APUM9) and APUM11, showed strongly enhanced transcript levels in rdo5 during seed imbibition. Further transgenic analyses indicated that APUM9 reduces seed dormancy. Interestingly, reduction of APUM transcripts by RNA interference complemented the reduced dormancy phenotype of rdo5, indicating that RDO5 functions by suppressing APUM transcript levels.
Over-expression of Arabidopsis AtCHR23 chromatin remodeling ATPase results in increased variability of growth and gene expression
Folta, A. ; Severing, E.I. ; Krauskopf, J. ; Geest, H.C. van de; Verver, J. ; Nap, J.P.H. ; Mlynarova, L. - \ 2014
BMC Plant Biology 14 (2014). - ISSN 1471-2229 - 18 p.
rna-seq - seed-germination - stress responses - root-growth - thaliana - plant - pickle - noise - identification - consequences
Background Plants are sessile organisms that deal with their -sometimes adverse- environment in well-regulated ways. Chromatin remodeling involving SWI/SNF2-type ATPases is thought to be an important epigenetic mechanism for the regulation of gene expression in different developmental programs and for integrating these programs with the response to environmental signals. In this study, we report on the role of chromatin remodeling in Arabidopsis with respect to the variability of growth and gene expression in relationship to environmental conditions. Results Already modest (2-fold) over-expression of the AtCHR23 ATPase gene in Arabidopsis results in overall reduced growth compared to the wild-type. Detailed analyses show that in the root, the reduction of growth is due to reduced cell elongation. The reduced-growth phenotype requires sufficient light and is magnified by applying deliberate abiotic (salt, osmotic) stress. In contrast, the knockout mutation of AtCHR23 does not lead to such visible phenotypic effects. In addition, we show that over-expression of AtCHR23 increases the variability of growth in populations of genetically identical plants. These data indicate that accurate and controlled expression of AtCHR23 contributes to the stability or robustness of growth. Detailed RNAseq analyses demonstrate that upon AtCHR23 over-expression also the variation of gene expression is increased in a subset of genes that associate with environmental stress. The larger variation of gene expression is confirmed in individual plants with the help of independent qRT-PCR analysis. Conclusions Over-expression of AtCHR23 gives Arabidopsis a phenotype that is markedly different from the growth arrest phenotype observed upon over-expression of AtCHR12, the paralog of AtCHR23, in response to abiotic stress. This demonstrates functional sub-specialization of highly similar ATPases in Arabidopsis. Over-expression of AtCHR23 increases the variability of growth among genetically identical individuals in a way that is consistent with increased variability of expression of a distinct subset of genes that associate with environmental stress. We propose that ATCHR23-mediated chromatin remodeling is a potential component of a buffer system in plants that protects against environmentally-induced phenotypic and transcriptional variation.
PIRIN2 stabilizes cysteine protease XCP2 and increases susceptibility to the vascular pathogen Ralstonia solanacearum in Arabidopsis
Zhang, B. ; Tremousaygue, D. ; Denancé, N. ; Esse, H.P. van; Hörger, A.C. ; Dabos, P. ; Goffner, D. ; Thomma, B.P.H.J. ; Hoorn, R.A.L. van der; Tuominen, H. - \ 2014
The Plant Journal 79 (2014)6. - ISSN 0960-7412 - p. 1009 - 1019.
programmed cell-death - nf-kappa-b - disease resistance - phytophthora-infestans - gene-expression - plants - xylem - thaliana - effector - defense
PIRIN (PRN) is a member of the functionally diverse cupin protein superfamily. There are four members of the Arabidopsis thaliana PRN family, but the roles of these proteins are largely unknown. Here we describe a function of the Arabidopsis PIRIN2 (PRN2) that is related to susceptibility to the bacterial plant pathogen Ralstonia solanacearum. Two prn2 mutant alleles displayed decreased disease development and bacterial growth in response to R. solanacearum infection. We elucidated the underlying molecular mechanism by analyzing PRN2 interactions with the papain-like cysteine proteases (PLCPs) XCP2, RD21A, and RD21B, all of which bound to PRN2 in yeast two-hybrid assays and in Arabidopsis protoplast co-immunoprecipitation assays. We show that XCP2 is stabilized by PRN2 through inhibition of its autolysis on the basis of PLCP activity profiling assays and enzymatic assays with recombinant protein. The stabilization of XCP2 by PRN2 was also confirmed in planta. Like prn2 mutants, an xcp2 single knockout mutant and xcp2 prn2 double knockout mutant displayed decreased susceptibility to R. solanacearum, suggesting that stabilization of XCP2 by PRN2 underlies susceptibility to R. solanacearum in Arabidopsis.
Phenotypic analyses of Arabidopsis T-DNA insertion lines and expression profiling reveal that multiple L-type lectin receptor kinases are involved in plant immunity
Wang, Y. ; Bouwmeester, K. ; Beseh, P. ; Shan, W. ; Govers, F. - \ 2014
Molecular Plant-Microbe Interactions 27 (2014)12. - ISSN 0894-0282 - p. 1390 - 1402.
pattern-triggered immunity - phytophthora-infestans - salicylic-acid - defense responses - innate immunity - thaliana - gene - resistance - biology - roles
L-type lectin receptor kinases (LecRKs) are membrane-spanning receptor-like kinases with putative roles in biotic and abiotic stress responses and in plant development. In Arabidopsis, 45 LecRKs were identified but their functions are largely unknown. Here, a systematic functional analysis was carried out by evaluating phenotypic changes of Arabidopsis LecRK T-DNA insertion lines in plant development and upon exposure to various external stimuli. None of the LecRK T-DNA insertion lines showed clear developmental changes, neither under normal conditions nor upon abiotic stress treatment. However, many of the T-DNA insertion lines showed altered resistance to Phytophthora brassicae, Phytophthora capsici, Pseudomonas syringae or Alternaria brassicicola. One mutant defective in LecRK-V.5 expression, was compromised in resistance to two Phytophthora spp. but showed enhanced resistance to P. syringae. LecRK-V.5 overexpression confirmed its dual role in resistance and susceptibility depending on the pathogen. Combined analysis of these phenotypic data and LecRK expression profiles retrieved from public datasets revealed that LecRKs which are hardly induced upon infection or even suppressed are also involved in pathogen resistance. Computed co-expression analysis revealed that LecRKs with similar function displayed diverse expression patterns. Since LecRKs are widespread in plants, the results presented here provide invaluable information for exploring the potential of LecRKs as novel sources of resistance in crops.
Interaction between parental environment and genotype affects plant and seed performance in Arabidopsis
He, H. ; Souza Vidigal, D. De; Snoek, L.B. ; Schnabel, S.K. ; Nijveen, H. ; Hilhorst, H. ; Bentsink, L. - \ 2014
Journal of Experimental Botany 65 (2014)22. - ISSN 0022-0957 - p. 6603 - 6615.
sativa miller brassicaceae - abscisic-acid biosynthesis - maturation environment - drought tolerance - natural variation - key enzyme - dormancy - germination - thaliana - temperature
Seed performance after dispersal is highly dependent on parental environmental cues, especially during seed formation and maturation. Here we examine which environmental factors are the most dominant in this respect and whether their effects are dependent on the genotypes under investigation. We studied the influence of light intensity, photoperiod, temperature, nitrate, and phosphate during seed development on five plant attributes and thirteen seed attributes, using 12 Arabidopsis genotypes that have been reported to be affected in seed traits. As expected, the various environments during seed development resulted in changed plant and/or seed performances. Comparative analysis clearly indicated that, overall, temperature plays the most dominant role in both plant and seed performance, whereas light has a prominent impact on plant traits. In comparison to temperature and light, nitrate mildly affected some of the plant and seed traits while phosphate had even less influence on those traits. Moreover, clear genotype-by-environment interactions were identified. This was shown by the fact that individual genotypes responded differentially to the environmental conditions. Low temperature significantly increased seed dormancy and decreased seed longevity of NILDOG1 and cyp707a1-1, whereas low light intensity increased seed dormancy and decreased seed longevity of NILDOG3 and NILDOG6. This also indicates that different genetic and molecular pathways are involved in the plant and seed responses. By identifying environmental conditions that affect the dormancy vs longevity correlation in the same way as previously identified naturally occurring loci, we have identified selective forces that probably shaped evolution for these important seed traits.
Assessment of pleiotropic transcriptome perturbations in Arabidopsis engineered for indirect insect defence
Houshyani Hassanzadeh, B. ; Krol, A.R. van der; Bino, R.J. ; Bouwmeester, H.J. - \ 2014
BMC Plant Biology 14 (2014). - ISSN 1471-2229
global gene-expression - metabolomics - thaliana - gm - biosynthesis - metabolism - emission - synthase - crops - wheat
Background: Molecular characterization is an essential step of risk/safety assessment of genetically modified (GM) crops. Holistic approaches for molecular characterization using omics platforms can be used to confirm the intended impact of the genetic engineering, but can also reveal the unintended changes at the omics level as a first assessment of potential risks. The potential of omics platforms for risk assessment of GM crops has rarely been used for this purpose because of the lack of a consensus reference and statistical methods to judge the significance or importance of the pleiotropic changes in GM plants. Here we propose a meta data analysis approach to the analysis of GM plants, by measuring the transcriptome distance to untransformed wild-types. Results: In the statistical analysis of the transcriptome distance between GM and wild-type plants, values are compared with naturally occurring transcriptome distances in non-GM counterparts obtained from a database. Using this approach we show that the pleiotropic effect of genes involved in indirect insect defence traits is substantially equivalent to the variation in gene expression occurring naturally in Arabidopsis. Conclusion: Transcriptome distance is a useful screening method to obtain insight in the pleiotropic effects of genetic modification.
Abscisic acid (ABA) sensitivity regulates desiccation tolerance in germinated Arabidopsis seeds
Maia de Oliveira, J. ; Dekkers, S.J.W. ; Dolle, M. ; Ligterink, W. ; Hilhorst, H.W.M. - \ 2014
New Phytologist 203 (2014)1. - ISSN 0028-646X - p. 81 - 93.
bzip transcription factors - medicago-truncatula seeds - 2c protein phosphatases - signal-transduction - drought tolerance - thaliana - stress - gene - maturation - expression
During germination, orthodox seeds lose their desiccation tolerance (DT) and become sensitive to extreme drying. Yet, DT can be rescued, in a well-defined developmental window, by the application of a mild osmotic stress before dehydration. A role for abscisic acid (ABA) has been implicated in this stress response and in DT re-establishment. However, the path from the sensing of an osmotic cue and its signaling to DT re-establishment is still largely unknown. Analyses of DT, ABA sensitivity, ABA content and gene expression were performed in desiccation- sensitive (DS) and desiccation-tolerant Arabidopsis thaliana seeds. Furthermore, loss and re-establishment of DT in germinated Arabidopsis seeds was studied in ABA-deficient and ABA-insensitive mutants. We demonstrate that the developmental window in which DT can be re-established correlates strongly with the window in which ABA sensitivity is still present. Using ABA biosynthesis and signaling mutants, we show that this hormone plays a key role in DT re-establishment. Surprisingly, re-establishment of DT depends on the modulation of ABA sensitivity rather than enhanced ABA content. In addition, the evaluation of several ABA-insensitive mutants, which can still produce normal desiccation-tolerant seeds, but are impaired in the re-establishment of DT, shows that the acquisition of DT during seed development is genetically different from its re-establishment during germination.
Phyllotaxis and Rhizotaxis in Arabidopsis Are Modified by Three PLETHORA Transcription Factors
Hofhuis, H. ; Laskowski, M. ; Du, Y.J. ; Prasad, K. ; Grigg, S. ; Pinon, V. ; Scheres, B. - \ 2013
Current Biology 23 (2013)11. - ISSN 0960-9822 - p. 956 - 962.
lateral root initiation - auxin transport - thaliana - growth - arf19 - gene - expression - nph4/arf7 - proteins - system
Background: The juxtaposition of newly formed primordia in the root and shoot differs greatly, but their formation in both contexts depends on local accumulation of the signaling molecule auxin. Whether the spacing of lateral roots along the main root and the arrangement of leaf primordia at the plant apex are controlled by related underlying mechanisms has remained unclear. Results: Here, we show that, in Arabidopsis thaliana, three transcriptional regulators implicated in phyllotaxis, PLETHORA3 (PLT3), PLT5, and PLT7, are expressed in incipient lateral root primordia where they are required for primordium development and lateral root emergence. Furthermore, all three PLT proteins prevent the formation of primordia close to one another, because, in their absence, successive lateral root primordia are frequently grouped in close longitudinal or radial clusters. The triple plt mutant phenotype is rescued by PLT-vYFP fusion proteins, which are expressed in the shoot meristem as well as the root, but not by expression of PLT7 in the shoot alone. Expression of all three PLT genes requires auxin response factors ARF7 and ARF19, and the reintroduction of PLT activity suffices to rescue lateral root formation in arf7,arf19. Conclusions: Intriguingly PLT 3, PLT5, and PLT7 not only control the positioning of organs at the shoot meristem but also in the root; a striking observation that raises many evolutionary questions.
Arabidopsis semidwarfs evolved from independent mutations in GA20ox1, ortholog to green revolution dwarf alleles in rice and barley
Barboza, L. ; Effgen, S. ; Alonso-Blanco, C. ; Kooke, R. ; Keurentjes, J.J.B. ; Koornneef, M. - \ 2013
Proceedings of the National Academy of Sciences of the United States of America 110 (2013)39. - ISSN 0027-8424 - p. 15818 - 15823.
quantitative trait loci - gibberellin biosynthesis - natural variation - thaliana - gene - populations - model - polymorphism - association - adaptation
Understanding the genetic bases of natural variation for developmental and stress-related traits is a major goal of current plant biology. Variation in plant hormone levels and signaling might underlie such phenotypic variation occurring even within the same species. Here we report the genetic and molecular basis of semidwarf individuals found in natural Arabidopsis thaliana populations. Allelism tests demonstrate that independent loss-offunction mutations at GA locus 5 (GA5), which encodes gibberellin 20-oxidase 1 (GA20ox1) involved in the last steps of gibberellin biosynthesis, are found in different populations from southern, western, and northern Europe; central Asia; and Japan. Sequencing of GA5 identified 21 different loss-of-function alleles causing semidwarfness without any obvious general tradeoff affecting plant performance traits. GA5 shows signatures of purifying selection, whereas GA5 loss-of-function alleles can also exhibit patterns of positive selection in specific populations as shown by Fay and Wu’s H statistics. These results suggest that antagonistic pleiotropy might underlie the occurrence of GA5 loss-of-function mutations in nature. Furthermore, because GA5 is the ortholog of rice SD1 and barley Sdw1/Denso green revolution genes, this study illustrates the occurrence of conserved adaptive evolution between wild A.thaliana and domesticated plants
Antiphase light and temperature cycles affect PHYTOCHROME B-controlled ethylene sensitivity and biosynthesis, limiting leaf movement and growth of Arabidopsis.
Bours, R.M.E.H. ; Zanten, M. van; Pierik, R. ; Bouwmeester, H.J. ; Krol, A.R. van der - \ 2013
Plant Physiology 163 (2013)2. - ISSN 0032-0889 - p. 882 - 895.
gene family - thermoperiodic responses - night temperature - circadian-rhythms - identify ethylene - stem elongation - thaliana - gibberellins - morphology - mutations
In the natural environment, days are generally warmer than the night, resulting in a positive day/night temperature difference (+DIF). Plants have adapted to these conditions, and when exposed to antiphase light and temperature cycles (cold photoperiod/warm night [-DIF]), most species exhibit reduced elongation growth. To study the physiological mechanism of how light and temperature cycles affect plant growth, we used infrared imaging to dissect growth dynamics under +DIF and -DIF in the model plant Arabidopsis (Arabidopsis thaliana). We found that -DIF altered leaf growth patterns, decreasing the amplitude and delaying the phase of leaf movement. Ethylene application restored leaf growth in -DIF conditions, and constitutive ethylene signaling mutants maintain robust leaf movement amplitudes under -DIF, indicating that ethylene signaling becomes limiting under these conditions. In response to -DIF, the phase of ethylene emission advanced 2 h, but total ethylene emission was not reduced. However, expression analysis on members of the 1-aminocyclopropane-1-carboxylic acid (ACC) synthase ethylene biosynthesis gene family showed that ACS2 activity is specifically suppressed in the petiole region under -DIF conditions. Indeed, petioles of plants under -DIF had reduced ACC content, and application of ACC to the petiole restored leaf growth patterns. Moreover, acs2 mutants displayed reduced leaf movement under +DIF, similar to wild-type plants under -DIF. In addition, we demonstrate that the photoreceptor PHYTOCHROME B restricts ethylene biosynthesis and constrains the -DIF-induced phase shift in rhythmic growth. Our findings provide a mechanistic insight into how fluctuating temperature cycles regulate plant growth.
Spatial coordination between stem cell activity and cell differentiation in the root meristem
Moubayidin, L. ; Mambro, R. Di; Sozzani, R. ; Pacifici, E. ; Salvi, E. ; Terpstra, I. ; Bao, D. ; Dijken, A. van; Dello loio, R. ; Perilli, S. ; Ljung, K. ; Benfey, P.N. ; Heidstra, R. ; Costantino, P. ; Sabatini, S. - \ 2013
Developmental Cell 26 (2013)4. - ISSN 1534-5807 - p. 405 - 415.
gras gene family - arabidopsis root - auxin biosynthesis - scarecrow - expression - thaliana - transport - division - growth - niche
A critical issue in development is the coordination of the activity of stem cell niches with differentiation of their progeny to ensure coherent organ growth. In the plant root, these processes take place at opposite ends of the meristem and must be coordinated with each other at a distance. Here, we show that in Arabidopsis, the gene SCR presides over this spatial coordination. In the organizing center of the root stem cell niche, SCR directly represses the expression of the cytokinin-response transcription factor ARR1, which promotes cell differentiation, controlling auxin production via the ASB1 gene and sustaining stem cell activity. This allows SCR to regulate, via auxin, the level of ARR1 expression in the transition zone where the stem cell progeny leaves the meristem, thus controlling the rate of differentiation. In this way, SCR simultaneously controls stem cell division and differentiation, ensuring coherent root growth.
The brassinosteroid insensitive1-like3 signalosome complex regulates Arabidopsis root development
Fàbregas, N. ; Li, N. ; Boeren, S. ; Nash, T.E. ; Goshe, M.B. ; Clouse, S.D. ; Vries, S.C. de; Caño-Delgado, A.I. - \ 2013
The Plant Cell 25 (2013)9. - ISSN 1040-4651 - p. 3377 - 3388.
receptor kinase bri1 - signaling pathways - statistical-model - plasma-membrane - gene-expression - transduction - growth - identification - thaliana - network
Brassinosteroid (BR) hormones are primarily perceived at the cell surface by the leucine-rich repeat receptor-like kinase brassinosteroid insensitive1 (BRI1). In Arabidopsis thaliana, BRI1 has two close homologs, BRI1-LIKE1 (BRL1) and BRL3, respectively, which are expressed in the vascular tissues and regulate shoot vascular development. Here, we identify novel components of the BRL3 receptor complex in planta by immunoprecipitation and mass spectrometry analysis. Whereas BRI1 associated kinase1 (BAK1) and several other known BRI1 interactors coimmunoprecipitated with BRL3, no evidence was found of a direct interaction between BRI1 and BRL3. In addition, we confirmed that BAK1 interacts with the BRL1 receptor by coimmunoprecipitation and fluorescence microscopy analysis. Importantly, genetic analysis of brl1 brl3 bak1-3 triple mutants revealed that BAK1, BRL1, and BRL3 signaling modulate root growth and development by contributing to the cellular activities of provascular and quiescent center cells. This provides functional relevance to the observed protein-protein interactions of the BRL3 signalosome. Overall, our study demonstrates that cell-specific BR receptor complexes can be assembled to perform different cellular activities during plant root growth, while highlighting that immunoprecipitation of leucine-rich repeat receptor kinases in plants is a powerful approach for unveiling signaling mechanisms with cellular resolution in plant development
Tightly controlled WRKY23 expression mediates Arabidopsis embryo development
Grunewald, W. ; Smet, I. De; Rybel, B. De; Robert, H.S. ; Cotte, B. van de; Willemsen, V.A. ; Gheysen, G. ; Weijers, D. ; Friml, J. ; Beeckman, T. - \ 2013
Embo Reports 14 (2013). - ISSN 1469-221X - p. 1136 - 1142.
stem-cell niche - transcription factor - root development - genes - axis - regulators - thaliana - proteins - encodes
The development of a multicellular embryo from a single zygote is a complex and highly organized process that is far from understood. In higher plants, apical–basal patterning mechanisms are crucial to correctly specify root and shoot stem cell niches that will sustain and drive post-embryonic plant growth and development. The auxin-responsive AtWRKY23 transcription factor is expressed from early embryogenesis onwards and the timing and localization of its expression overlaps with the root stem cell niche. Knocking down WRKY23 transcript levels or expression of a dominant-negative WRKY23 version via a translational fusion with the SRDX repressor domain affected both apical–basal axis formation as well as installation of the root stem cell niche. WRKY23 expression is affected by two well-known root stem cell specification mechanisms, that is, SHORTROOT and MONOPTEROS–BODENLOS signalling and can partially rescue the root-forming inability of mp embryos. On the basis of these results, we postulate that a tightly controlled WRKY23 expression is involved in the regulation of both auxin-dependent and auxin-independent signalling pathways towards stem cell specification.
Analysis of functional redundancies within the Arabidopsis TCP transcription factor family
Danisman, S. ; Dijk, A.D.J. van; Bimbo, A. ; Wal, F. van der; Hennig, L. ; Folter, S. de; Angenent, G.C. ; Immink, R.G.H. - \ 2013
Journal of Experimental Botany 64 (2013)18. - ISSN 0022-0957 - p. 5673 - 5685.
gene-expression map - leaf development - circadian clock - class-i - thaliana - evolution - proteins - growth - duplication - plants
Analyses of the functions of TEOSINTE-LIKE1, CYCLOIDEA, and ROLIFERATING CELL FACTOR1 (TCP) transcription factors have been hampered by functional redundancy between its individual members. In general, putative functionally redundant genes are predicted based on sequence similarity and confirmed by genetic analysis. In the TCP family, however, identification is impeded by relatively low overall sequence similarity. In a search for functionally redundant TCP pairs that control Arabidopsis leaf development, this work performed an integrative bioinformatics analysis, combining protein sequence similarities, gene expression data, and results of pair-wise protein–protein interaction studies for the 24 members of the Arabidopsis TCP transcription factor family. For this, the work completed any lacking gene expression and protein–protein interaction data experimentally and then performed a comprehensive prediction of potential functional redundant TCP pairs. Subsequently, redundant functions could be confirmed for selected predicted TCP pairs by genetic and molecular analyses. It is demonstrated that the previously uncharacterized class I TCP19 gene plays a role in the control of leaf senescence in a redundant fashion with TCP20. Altogether, this work shows the power of combining classical genetic and molecular approaches with bioinformatics predictions to unravel functional redundancies in the TCP transcription factor family.
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