The Melon Zym Locus Conferring Resistance to ZYMV: High Resolution Mapping and Candidate Gene Identification

Zucchini yellow mosaic virus (ZYMV; potyviridae) represents a major pathogen of Cucurbitaceae crops. ZYMV resistance in melon PI 414723 is conditioned by dominant allele at the Zym locus. This resistant accession restricts viral spread and does not develop symptoms, but necrosis sometimes develops response to inoculation. In previous studies, has been mapped linkage group II genetic map. present study, positional cloning locus was undertaken, starting from CM-AG36 SSR marker approximately 2 cm distance. We utilized five mapping populations that share same parent, 414723, analyzed total 1630 offspring, construct high-resolution map Two BAC libraries were used for chromosome walking developing new markers closer gene BAC-end sequencing. A contig constructed, we identified single clone, susceptible genotype MR-1, physically encompasses gene. second clone isolated another genotype, WMR 29, two clones fully sequenced annotated. Additional derived region delimited 17.6 kb sequence harbors NAC-like transcription factor and, depending on either or three R-gene homologs with CC-NBS-LRR structure. Mapping confirmed saturating SNP using population. The amplified also 414723. Because numerous polymorphic sites noted between genotypes, could associate specific DNA polymorphism; however, this study enables molecular identification paves way functional studies important