Screening of Cucurbit Germplasm for Resistance to Cucumber mosaic virus, Papaya ringspot virus and Zucchini yellow mosaic virus

Abstract

A total of 169 cucurbit accessions includes 34 accessions of pumpkin (Cucurbita moschata), 69 accessions of angled loofah (Luffa acutangula) and 66 accessions of watermelon (Citrullus lanatus) obtained from Clover Seed Ltd. (Thailand) were screened for resistance to Cucumber mosaic virus (CMV) isolate NK10 (CMV-NK10), Papaya ringspot virus (PRSV) isolate Cu014 (PRSV-Cu014) and Zucchini yellow mosaic virus (ZYMV) isolate Cu012 (ZYMV-Cu012) under greenhouse conditions. Mechanical inoculation of the first and second true leaves was done by rubbing with a mixture of virus inoculum and carborundum. Four weeks after inoculation, all plants were evaluated visually for symptoms of virus infection and tested by Indirect plate trapped antigen ELISA (indirect PTA-ELISA) to determine virus presence in upper, non-inoculated leaf tissue. Disease rating based on percent of infected plants classified accessions as immune, resistant, moderate resistant, moderate susceptible and susceptible. Twelve accessions of angled loofah were immune to our isolates of all three viruses. Almost all tested accessions were immune to CMV-NK10 include eighteen accessions of pumpkin, fifty accessions of angled loofah and sixty six accessions of watermelon. Seventeen and five accessions of angled loofah and watermelon, respectively, were immune to PRSV-Cu014. Sixty six accessions of angled loofah were immune to ZYMV-Cu012. The immune accessions identified in this study may prove to be significant new sources of CMV, PRSV and ZYMV resistance for breeding programs for cultivar development.