Publications by authors named "Joachim Kilian"

In annual plants, tight coordination of successive developmental events is of primary importance to optimize performance under fluctuating environmental conditions. The recent finding of the genetic interaction of WRKY53, a key senescence-related gene with REVOLUTA, a master regulator of early leaf patterning, raises the question of how early and late developmental events are connected. Here, we investigated the developmental and metabolic consequences of an alteration of the REVOLUTA and WRKY53 gene expression, from seedling to fruiting.

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5-Deoxyadenosine (5dAdo) is the byproduct of many radical S-adenosyl-l-methionine enzyme reactions in all domains of life. 5dAdo is also an inhibitor of the radical S-adenosyl-l-methionine enzymes themselves, making it necessary for cells to construct pathways to recycle or dispose of this toxic metabolite. However, the specific pathways involved have long remained unexplored.

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Plants deposit hydrophobic polymers, such as lignin or suberin, in their root cell walls to protect inner tissues and facilitate selective uptake of solutes. Insights into how individual root tissues contribute to polymer formation are important for elucidation of ultrastructure, function, and development of these protective barriers. Although the pathways responsible for production of the barrier constituents are established, our models lack spatiotemporal resolution-especially in roots-thus, the source of monomeric barrier components is not clear.

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Plants have evolved effective strategies to defend themselves against pathogen invasion. Starting from the plasma membrane with the recognition of microbe-associated molecular patterns (MAMPs) via pattern recognition receptors, internal cellular signaling pathways are induced to ultimately fend off the attack. Phospholipase D (PLD) hydrolyzes membrane phospholipids to produce phosphatidic acid (PA), which has been proposed to play a second messenger role in immunity.

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The pepper () resistance gene () is transcriptionally activated by the matching transcription-activator-like effector (TALE) AvrBs3. AvrBs3-induced expression triggers a rapid and local cell death reaction, the hypersensitive response (HR). Bs3 is most closely related to plant flavin monooxygenases of the YUCCA (YUC) family, which catalyze the final step in auxin biosynthesis.

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Pattern recognition receptors (PRRs) sense microbial patterns and activate innate immunity against attempted microbial invasions. The leucine-rich repeat receptor kinases (LRR-RK) FLS2 and EFR, and the LRR receptor protein (LRR-RP) receptors RLP23 and RLP42, respectively, represent prototypical members of these two prominent and closely related PRR families. We conducted a survey of Arabidopsis thaliana immune signaling mediated by these receptors to address the question of commonalities and differences between LRR-RK and LRR-RP signaling.

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Polycomb-repressive complexes (PRCs) play key roles in development by repressing a large number of genes involved in various functions. Much, however, remains to be discovered about PRC-silencing mechanisms as well as their targeting to specific genomic regions. Besides other mechanisms, GAGA-binding factors in animals can guide PRC members in a sequence-specific manner to Polycomb-responsive DNA elements.

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In multicellular organisms, cellular differences in gene activity are a prerequisite for differentiation and establishment of cell types. In order to study transcriptome profiles, specific cell types have to be isolated from a given tissue or even the whole organism. However, whole-transcriptome analysis of early embryos in flowering plants has been hampered by their size and inaccessibility.

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Studying plant stress responses is an important issue in a world threatened by global warming. Unfortunately, comparative analyses are hampered by varying experimental setups. In contrast, the AtGenExpress abiotic stress experiment displays intercomparability.

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Background: In higher plants, a diverse array of developmental and growth-related processes is regulated by the plant hormone auxin. Recent publications have proposed that besides the well-characterized Auxin Response Factors (ARFs) that bind Auxin Response Elements (AuxREs), also members of the bZIP- and MYB-transcription factor (TF) families participate in transcriptional control of auxin-regulated genes via bZIP Response Elements (ZREs) or Myb Response Elements (MREs), respectively.

Results: Applying a novel bioinformatic algorithm, we demonstrate on a genome-wide scale that singular motifs or composite modules of AuxREs, ZREs, MREs but also of MYC2 related elements are significantly enriched in promoters of auxin-inducible genes.

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Interactions with the (a)biotic environment play key roles in a plant's fitness and vitality. In addition to direct surface-to-surface contact, volatile chemicals can also affect the physiology of organism. Volatiles of Serratia plymuthica and Stenotrophomonas maltophilia significantly inhibited growth and induced H(2) O(2) production in Arabidopsis in dual culture.

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The process of chloroplast biogenesis requires a multitude of pathways and processes to establish chloroplast function. In cotyledons of seedlings, chloroplasts develop either directly from proplastids (also named eoplasts) or, if germinated in the dark, via etioplasts, whereas in leaves chloroplasts derive from proplastids in the apical meristem and are then multiplied by division. The snowy cotyledon 2, sco2, mutations specifically disrupt chloroplast biogenesis in cotyledons.

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During the last decade, microarrays became a routine tool for the analysis of transcripts in the model plant Arabidopsis thaliana and the crop plant species rice, poplar or barley. The overwhelming amount of data generated by gene expression studies is a valuable resource for every scientist. Here, we summarize the most important findings about the abiotic stress responses in plants.

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The plasma membrane-spanning receptor brassinosteroid insenstive 1 (BRI1) rapidly induces plant cell wall expansion in response to brassinosteroids such as brassinolide (BL). Wall expansion is accompanied by a rapid hyperpolarisation of the plasma membrane which is recordable by measuring the fluorescence lifetime (FLT) of the green fluorescent protein (GFP) fused to BRI1. For the BL induction of hyperpolarisation and wall expansion, the activation of the plasma membrane P-type H+-ATPase is necessary.

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High-temperature stress, like any abiotic stress, impairs the physiology and development of plants, including the stages of seed setting and ripening. We used the Affymetrix 22K Barley1 GeneChip microarray to investigate the response of developing barley (Hordeum vulgare) seeds, termed caryopses, after 0.5, 3, and 6 h of heat stress exposure; 958 induced and 1122 repressed genes exhibited spatial and temporal expression patterns that provide a detailed insight into the caryopses' early heat stress responses.

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The caryopses of barley (Hordeum vulgare), as of all cereals, are complex sink organs optimized for starch accumulation and embryo development. While their early to late development has been studied in great detail, processes underlying the caryopses' diurnal adaptation to changes in light, temperature, and the fluctuations in phloem-supplied carbon and nitrogen have remained unknown. In an attempt to identify diurnally affected processes in developing caryopses at the early maturation phase, we monitored global changes of both gene expression and metabolite levels.

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Background: WRKY proteins belong to the WRKY-GCM1 superfamily of zinc finger transcription factors that have been subject to a large plant-specific diversification. For the cereal crop barley (Hordeum vulgare), three different WRKY proteins have been characterized so far as regulators in sucrose signaling, pathogen defense, and in response to cold and drought. However, their phylogenetic relationship remained unresolved.

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The tolerance responses of plants to many abiotic stresses are conjectured to be controlled by complex gene networks. In the frame of the AtGenExpress project a comprehensive Arabidopsis thaliana genome transcript expression study was performed using the Affymetrix ATH1 microarray in order to understand these regulatory networks in detail. In contrast to earlier studies, we subjected, side-by-side and in a high-resolution kinetic series, Arabidopsis plants, of identical genotype grown under identical conditions, to different environmental stresses comprising heat, cold, drought, salt, high osmolarity, UV-B light and wounding.

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The exoribonuclease polynucleotide phosphorylase (PNPase) has been implicated in mRNA processing and degradation in bacteria as well as in chloroplasts of higher plants. Here, we report the first comprehensive in vivo study of chloroplast PNPase function. Modulation of PNPase activity in Arabidopsis chloroplasts by a reverse genetic approach revealed that, although this enzyme is essential for efficient 3'-end processing of mRNAs, it is insufficient to mediate transcript degradation.

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