Plant-pathogen interactions controlled by the Fom-1/Prv and Fom-2 loci of melon

摘要

We cloned the genomic locus for melon resistance towards Fusarium oxysporum f.sp. melonis (FOM) races 0 and 1, and the Papaya ring spot virus (PRSV). The two adjacent genes encode proteins of the NBL (nucleotide binding site-leucine rich repeat) family; Prv carries an extra NB domain, and both have alternative, differentially expressed splice variants. The genes' expression patterns were studied using a promoter-reporter system in transgenic melon roots: both genes were expressed around the vasculartissue and in root tips. In our quest for possible fungal proteins that could interact with Fom-2, another resistance gene, we isolated FOM homologs of secreted in xylem (six) genes that, in Fusarium oxysporum f.sp. lycopersici, encode Avr factors. Two such homologs were found, but their distribution among FOM races did not fit the "gene for gene" model. We performed a proteomic analysis of the xylem sap of melon plants that were infected with FOM-0. A total of 513 melon protein and 9 fungal proteins could be annotated against the melon and FOM genomes, respectively. Many of the melon proteins were up-regulated by inoculation.