Functional and applied aspects of the DOWNY MILDEW RESISTANT 1 and 6 genes in Arabidopsis

摘要: Plants are constantly exposed to micro-organisms including pathogens. They resistant the vast majority of potential pathogens due a multilayered defence system. Plant disease susceptibility, on other hand, is determined by virulence factors from pathogen, their targets in host and successful suppression plant defences. To gain insight into molecular mechanisms underlying we study interaction between oomycete pathogen Hyaloperonospora arabidopsidis, causing downy mildew, its Arabidopsis. A forward genetic screen resulted several mildew (dmr) Arabidopsis mutants which dmr1 dmr6 were further characterized. Chapter 2 described cloning DMR1 that encodes for homoserine kinase (HSK), key enzyme Aspartate pathway. Mutation HSK mutant accumulation amino acid homoserine. Exogenous application proved be sufficient induce resistance against H. arabidopsidis. No known defence-related pathways associated with observed resistance, indicating triggers novel form resistance. was analysed chapter 3 where reverse genetics approach (TILLING) additional hsk alleles. One accumulated infection. Another did not develop beyond seedling stage suggesting an essential gene. We also identified orthologs number crop species making them candidates mutagenesis explore dmr1-mediated 4 characterization DMR6 gene, coding 2-oxoglutarate Fe(II)-dependent oxygenase. Absence functional gene requires salicylic On overexpression enhanced susceptibility towards biotrophic acts as negative regulator defence. 3-dimensional model constructed protein facilitated identification important residues substrate pocket. 5 family DMR6-like oxygenases (DLOs) role Two DLOs, through phylogenetic analysis, have similar function DMR6. Also, able complement dmr6-mediated DMR6/DLO-specific motif could used or DLO proteins. The presence this conserved determine specificity particular shared different species.