Cloning and functional characterization of the vec1 resistance gene

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The first funding period resulted in the identification of several major QTL controlling multiple disease parameters such as resistance to systemic spread or to stunting caused by V. longisporum in Arabidopsis and Brassica. The focus of the new application is the molecular identification of the responsible gene(s) in Arabidopsis. A combination of different approaches will be pursued to achieve the cloning of a gene which is controlling host resistance against systemic spread of the fungus. The basis of these approaches will be the continuation of fine-mapping in a population of NILs which differ only in a small segment on chromosome 2 which carries at least one gene controlling spreading resistance (vec1) and also the erecta locus. The latter has been shown to be responsible for stunting resistance. Fine-mapping and expression studies in tailor-made NILs (infected vs. non-infected) will allow identifying a small number of candidate genes. To identify vec1 these will be cloned and analysed for their effect on spreading resistance after complementation in the susceptible ecotype Ler. The effect of vec1 on defence signalling will be studied in expression studies and grafting experiments. Histological defence reactions will be studied microscopically. Homologous genes in Brassica will be searched and analysed for their correlation to resistance in existing mapping populations of Brassica crops, which will allow the application of our results in oilseed rape breeding.