Publikationen - Molekulare Signalverarbeitung

Background:The formation of flowers is one of the main model systems to elucidate the molecular mechanisms that control developmental processes in plants. Although several studies have explored gene expression during flower development in the model plant Arabidopsis thalianaon a genome-wide scale, a continuous series of expression data from the earliest floral stages until maturation has been lacking. Here, we used a floral induction system to closethis information gap and to generate a reference dataset for stage-specific gene expression during flower formation.Results:Using a floral induction system, we collected floral buds at 14 different stages from the time of initiation until maturation. Using whole-genome microarray analysis, we identified 7,405 genes that exhibit rapid expression changes during flower development. These genes comprise many known floral regulators and we found that the expression profiles for these regulators match their known expression patterns, thus validating the dataset. We analyzed groups ofco-expressed genes for over-represented cellular and developmental functions through Gene Ontology analysis and found that they could be assigned specific patterns of activities, which are in agreement with the progression of flower development. Furthermore, by mapping binding sites of floral organ identity factors onto our dataset, we were able to identify gene groups that are likely predominantly under control of these transcriptional regulators. We furtherfound that the distribution of paralogs among groups of co-expressed genes varies considerably, with genes expressed predominantly at early and intermediate stages of flower development showing the highest proportion of such genes.Conclusions:Our results highlight and describe the dynamic expression changes undergone by a large numberof genes during flower development. They further provide a comprehensive reference dataset for temporal gene expression during flower formation and we demonstrate that it can be used to integrate data from other genomics approaches such as genome-wide localization studies of transcription factor binding sites.

Jasmonsäure (JA) und ihre Metaboliten kommen in allen niederen und höheren Pflanzen vor. Sie sind universell wirksame, aus Lipiden gebildete Signalstoffe bei der Abwehr von biotischem und abiotischem Stress sowie in der pflanzlichen Entwicklung. Rezeptor und Komponenten von JA–Signalketten wurden identifiziert. In der Entwicklung von Blüten, Früchten, Samen, Trichomen oder in der Abwehr von Insekten und Pathogenen treten ähnliche JA-vermittelte Signalproteine auf, die eine Feinregulation der Prozesse erlauben und eine Verbindung (cross-talk) zu anderenPflanzenhormonen aufweisen.

The definition of a plant hormone has not been clearly established, so the compounds classified as plant hormones often vary depending on which definition is considered. In this chapter, auxins, gibberellins (GAs), cytokinins, abscisic acid, brassinosteroids, jasmonic acid-related compounds, and ethylene are described as established plant hormones, while polyamines and phenolic compounds are not included. On the other hand, several peptides that have been proven to play a clear physiological role(s) in plant growth and development, similar to the established plant hormones, are referred. This chapter will focus primarily on the more recent discoveries of plant hormones and their impact on our current understanding of their biological role. In some cases, however, it is critical to place recent work in a proper historical context.

Immature scutella of barley were transformed with cDNA coding for a 13-li-poxygenase of barley (LOX-100) via particle bombardment. Regenerated plants were tested by PAT-assay, Western-analysis and PCR-screening. Immunocytochemical assay of T0 plants showed expression of the LOX cDNA both in the chloroplasts and in the cytosol, depending on the presence of the chloroplast signal peptide sequences in the cDNA. A few transgenic plants containing higher amounts of LOX-derived products have been found. These are the candidates for further analysis concerning pathogen resistance.

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