Elucidation of resistance signaling and identification of powdery mildew resistant mapping loci (ClaPMR2) during watermelon-Podosphaera xanthii interaction using RNA-Seq and whole-genome resequencing approach

Watermelon is an important vegetable crop and is widely cultivated in USA with an approximate global production of > 100 million tons. Powdery mildew caused by Podosphaera xanthii is a major production-limiting factor on watermelon and other cucurbits. Numerous PM and multiple disease resistant watermelon germplasm lines have been developed by the USDA in Charleston, SC. To gain a better understanding of the innate and activated molecular defense mechanisms involved during compatible and incompatible PM-watermelon interactions, we inoculated PM susceptible and resistant watermelon plants with P. xanthii. RNA-seq profiling was done on leaf samples collected at 0, 1, 3, and 8 days post inoculation. A total of 2,566 unique differentially expressed genes were identified between compatible and incompatible interactions with P. xanthii.