Resistance in melon to Cucurbit chlorotic yellows virus, a whitefly-transmitted crinivirus

Fifty-one melon (Cucumis melo) accessions that originated from India, Pakistan and Bangladesh were evaluated for resistance to Cucurbit chlorotic yellows virus (CCYV), a newly emerged species in the genus Crinivirus. CCYV was inoculated using sweet potato whitefly (Bemisia tabaci) biotype Q. Accessions, JP 138332, JP 216154, JP 216155, JP 216751 and JP 91204, showed no or faint symptoms, although CCYV was detected from the non-inoculated upper leaves by reverse transcription-polymerase chain reaction (RT-PCR). The five accessions were subjected to quantitative RT-PCR to analyze relative accumulation of CCYV RNA. All accessions except JP 138332 had levels of CCYV RNA accumulation comparable to the commercial variety, ‘Earl’s Seine’, which was used as a control. JP 138332 showed a much lower CCYV RNA accumulation. Numbers of B. tabaci biotype Q on JP 138332 did not differ from ‘Earl’s Seine’, in antixenosis tests, and the result suggested the resistance to CCYV was not due to antixenosis. Consequently, five accessions are of interest for development of resistant varieties. In particular, JP 138332 possesses a promising resistant trait for CCYV, which might be associated with inhibition of virus multiplication.