Biosynthesis of gibberellin plant hormons by pathogenic bacteria

赤霉素是一种植物激素，可以协调它们精确的发育。它们对调节茎的伸长、萌发、休眠、开花、叶片衰老和果实发育都很重要。最近，还发现赤霉素可以改变植物对食草动物和病原体的防御诱导。由于这些原因，人们对植物的生物合成和作用方式进行了很好的研究，并研究了引起Bakanae病的植物病原真菌--Gibberella fujikuroi，受感染的水稻植株生长过快，经常倒下。然而，除了病原真菌外，病原细菌似乎也能产生赤霉素。水稻病原菌Xanthomonas oryzae PV中最近证实存在赤霉素生物合成操纵子。Oryzicola和小麦/大麦病原菌半透明黄单胞菌(Xanthomonas Halucucens PV.)半透明和光伏。麦片。对生物合成操纵子中存在的基因的分析表明，与植物或真菌相比，细菌中赤霉素生物合成的后期步骤涉及不同的基因，这表明赤霉素的生物合成可能分别进化了三次。该项目旨在阐明在这些黄单胞菌中赤霉素生物合成的潜在生化途径。详细地，以及表征赤霉素与植物-病原菌相互作用的相关性。

Gibberellins are plant hormones that coordinate their precisely timed development. They are important for regulation of e.g. stem elongation, germination, dormancy, flowering, leaf senescence and fruit development. More recently it was also revealed that gibberellins can alter the induction of plant defense against herbivores and pathogens. For those reasons biosynthesis and the mode of action are well studied in plants and the plant pathogenic fungi Gibberella fujikuroi causing the bakanae disease, where infected rice plants grow too rapidly and often fall over. However besides pathogenic fungi, also pathogenic bacteria seem to be able to produce gibberellins. The presence of a gibberellin biosynthetic operon was recently confirmed in the rice pathogen Xanthomonas oryzae pv. oryzicola and the wheat/barley pathogens Xanthomonas translucens pv. translucens and pv. graminis. An analysis of the genes present in the biosynthetic operon shows that different genes are involved in the later steps of gibberellin biosynthesis in bacteria compared to plants or fungi, indicating that gibberellin biosynthesis may evolved separately three times. The proposed project aims to elucidate the underlying biochemical pathway for gibberellin biosynthesis in these Xanthomonas spp. in detail, as well as to characterize the relevance of gibberellins for plant-pathogen interaction.