Gregor Mendel Institute of Molecular Plant Biology

Vienna, Austria

Gregor Mendel Institute of Molecular Plant Biology

Vienna, Austria

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Pecinka A.,Max Planck Institute for Plant Breeding Research | Mittelsten Scheid O.,Gregor Mendel Institute of Molecular Plant Biology
Plant and Cell Physiology | Year: 2012

The investigation of stress responses has been a focus of plant research, breeding and biotechnology for a long time. Insight into stress perception, signaling and genetic determinants of resistance has recently been complemented by growing evidence for substantial stress-induced changes at the chromatin level. These affect specific sequences or occur genome-wide and are often correlated with transcriptional regulation. The majority of these changes only occur during stress exposure, and both expression and chromatin states typically revert to the pre-stress state shortly thereafter. Other changes result in the maintenance of new chromatin states and modified gene expression for a longer time after stress exposure, preparing an individual for developmental decisions or more effective defence. Beyond this, there are claims for stress-induced heritable chromatin modifications that are transmitted to progeny, thereby improving their characteristics. These effects resemble the concept of Lamarckian inheritance of acquired characters and represent a challenge to the uniqueness of DNA sequence-based inheritance. However, with the growing insight into epigenetic regulation and transmission of chromatin states, it is worth investigating these phenomena carefully. While genetic changes (mainly transposon mobility) in response to stress-induced interference with chromatin are well documented and heritable, in our view there is no unambiguous evidence for transmission of exclusively chromatin-controlled stress effects to progeny. We propose a set of criteria that should be applied to substantiate the data for stress-induced, chromatin-encoded new traits. Well-controlled stress treatments, thorough phenotyping and application of refined genome-wide epigenetic analysis tools should be helpful in moving from interesting observations towards robust evidence. © 2012 The Author.

Kawashima T.,National University of Singapore | Kawashima T.,Gregor Mendel Institute of Molecular Plant Biology | Berger F.,National University of Singapore | Berger F.,Gregor Mendel Institute of Molecular Plant Biology
Nature Reviews Genetics | Year: 2014

Epigenetic reprogramming consists of global changes in DNA methylation and histone modifications. In mammals, epigenetic reprogramming is primarily associated with sexual reproduction and occurs during both gametogenesis and early embryonic development. Such reprogramming is crucial not only to maintain genomic integrity through silencing transposable elements but also to reset the silenced status of imprinted genes. In plants, observations of stable transgenerational inheritance of epialleles have argued against reprogramming. However, emerging evidence supports that epigenetic reprogramming indeed occurs during sexual reproduction in plants and that it has a major role in maintaining genome integrity and a potential contribution to epiallelic variation. © 2014 Macmillan Publishers Limited. All rights reserved.

Pikaard C.S.,Howard Hughes Medical Institute | Scheid O.M.,Gregor Mendel Institute of Molecular Plant Biology
Cold Spring Harbor Perspectives in Biology | Year: 2014

The study of epigenetics in plants has a long and rich history, from initial descriptions of non-Mendelian gene behaviors to seminal discoveries of chromatin-modifying proteins and RNAs that mediate gene silencing in most eukaryotes, including humans. Genetic screens in the model plant Arabidopsis have been particularly rewarding, identifying more than 130 epigenetic regulators thus far. The diversity of epigenetic pathways in plants is remarkable, presumably contributing to the phenotypic plasticity of plant postembryonic development and the ability to survive and reproduce in unpredictable environments. © 2014 Cold Spring Harbor Laboratory Press; all rights reserved.

Krasensky J.,Gregor Mendel Institute of Molecular Plant Biology | Jonak C.,Gregor Mendel Institute of Molecular Plant Biology
Journal of Experimental Botany | Year: 2012

Plants regularly face adverse growth conditions, such as drought, salinity, chilling, freezing, and high temperatures. These stresses can delay growth and development, reduce productivity, and, in extreme cases, cause plant death. Plant stress responses are dynamic and involve complex cross-talk between different regulatory levels, including adjustment of metabolism and gene expression for physiological and morphological adaptation. In this review, information about metabolic regulation in response to drought, extreme temperature, and salinity stress is summarized and the signalling events involved in mediating stress-induced metabolic changes are presented. © 2011 The Author.

Furner I.J.,University of Cambridge | Matzke M.,Gregor Mendel Institute of Molecular Plant Biology
Current Opinion in Plant Biology | Year: 2011

The primary sequence of the genome is broadly constant and superimposed upon that constancy is the postreplicative modification of a small number of cytosine residues to 5-methylcytosine. The pattern of methylation is non-random; some sequence contexts are frequently methylated and some rarely methylated and some regions of the genome are highly methylated and some rarely methylated. Once established, methylation is not static: it can potentially change in response to developmental or environmental cues and this may result in correlated changes in gene expression. Changes can occur passively owing to a failure to maintain DNA methylation through rounds of DNA replication, or actively, through the action of enzymes with DNA glycosylase activity. Recent advances in genetic analyses and the generation of high resolution, genome-wide methylation maps are revealing in unprecedented detail the patterns and dynamic changes of DNA methylation in plants. © 2010 Elsevier Ltd.

Meijon M.,Gregor Mendel Institute of Molecular Plant Biology | Meijon M.,Regional Institute for Research and Agro Food Development SERIDA | Satbhai S.B.,Gregor Mendel Institute of Molecular Plant Biology | Tsuchimatsu T.,Gregor Mendel Institute of Molecular Plant Biology | Busch W.,Gregor Mendel Institute of Molecular Plant Biology
Nature Genetics | Year: 2014

With the increased availability of high-resolution sequence information, genome-wide association (GWA) studies have become feasible in a number of species. The vast majority of these studies are conducted in human populations, where it is difficult to provide strong evidence for the functional involvement of unknown genes that are identified using GWA. Here we used the model organism Arabidopsis thaliana to combine high-throughput confocal microscopy imaging of traits at the cellular level, GWA and expression analyses to identify genomic regions that are associated with developmental cell-type traits. We identify and characterize a new F-box gene, KUK, that regulates meristem and cell length. We further show that polymorphisms in the coding sequence are the major causes of KUK allele-dependent natural variation in root development. This work demonstrates the feasibility of GWA using cellular traits to identify causal genes for basic biological processes such as development. © 2014 Nature America, Inc.

Gutzat R.,Gregor Mendel Institute of Molecular Plant Biology | Mittelsten Scheid O.,Gregor Mendel Institute of Molecular Plant Biology
Current Opinion in Plant Biology | Year: 2012

Stressful conditions for plants can originate from numerous physical, chemical and biological factors, and plants have developed a plethora of survival strategies including developmental and morphological adaptations, specific signaling and defense pathways as well as innate and acquired immunity. While it has become clear in recent years that many stress responses involve epigenetic components, we are far from understanding the mechanisms and molecular interactions. Extending our knowledge is fundamental, not least for plant breeding and conservation biology. This review will highlight recent insights into epigenetic stress responses at the level of signaling, chromatin modification, and potentially heritable consequences. © 2012 Elsevier Ltd.

Vrbsky J.,Gregor Mendel Institute of Molecular Plant Biology
PLoS genetics | Year: 2010

Chromosome termini form a specialized type of heterochromatin that is important for chromosome stability. The recent discovery of telomeric RNA transcripts in yeast and vertebrates raised the question of whether RNA-based mechanisms are involved in the formation of telomeric heterochromatin. In this study, we performed detailed analysis of chromatin structure and RNA transcription at chromosome termini in Arabidopsis. Arabidopsis telomeres display features of intermediate heterochromatin that does not extensively spread to subtelomeric regions which encode transcriptionally active genes. We also found telomeric repeat-containing transcripts arising from telomeres and centromeric loci, a portion of which are processed into small interfering RNAs. These telomeric siRNAs contribute to the maintenance of telomeric chromatin through promoting methylation of asymmetric cytosines in telomeric (CCCTAAA)(n) repeats. The formation of telomeric siRNAs and methylation of telomeres relies on the RNA-dependent DNA methylation pathway. The loss of telomeric DNA methylation in rdr2 mutants is accompanied by only a modest effect on histone heterochromatic marks, indicating that maintenance of telomeric heterochromatin in Arabidopsis is reinforced by several independent mechanisms. In conclusion, this study provides evidence for an siRNA-directed mechanism of chromatin maintenance at telomeres in Arabidopsis.

Tamaru H.,Gregor Mendel Institute of Molecular Plant Biology
Genes and Development | Year: 2010

Heterochromatin is typically highly condensed, gene-poor, and transcriptionally silent, whereas euchromatin is less condensed, gene-rich, andmore accessible to transcription. Besides acting as a graveyard for selfish mobile DNA repeats, heterochromatin contributes to important biological functions, such as chromosome segregation during cell division. Multiple features of heterochromatin - including the presence or absence of specific histone modifications, DNAmethylation, and small RNAs - have been implicated in distinguishing heterochromatin from euchromatin in various organisms. Cells malfunction if the genome fails to restrict repressive chromatin marks within heterochromatin domains. How euchromatin and heterochromatin territories are confined remains poorly understood. Recent studies from the fission yeast Schizosaccharomyces pombe, the flowering plant Arabidopsis thaliana, and the filamentous fungusNeurospora crassa have revealed a new role for Jumonji C (JmjC) domain-containing proteins in protecting euchromatin from heterochromatin marks. © 2010 by Cold Spring Harbor Laboratory Press.

Platzer A.,Gregor Mendel Institute of Molecular Plant Biology
PLoS ONE | Year: 2013

Background: Single Nucleotide Polymorphisms (SNPs) are one of the largest sources of new data in biology. In most papers, SNPs between individuals are visualized with Principal Component Analysis (PCA), an older method for this purpose. Principal Findings: We compare PCA, an aging method for this purpose, with a newer method, t-Distributed Stochastic Neighbor Embedding (t-SNE) for the visualization of large SNP datasets. We also propose a set of key figures for evaluating these visualizations; in all of these t-SNE performs better. Significance: To transform data PCA remains a reasonably good method, but for visualization it should be replaced by a method from the subfield of dimension reduction. To evaluate the performance of visualization, we propose key figures of cross-validation with machine learning methods, as well as indices of cluster validity. © 2013 Alexander Platzer.

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