EVALUATION OF REACTION OF SOME IRANIAN MELON ACCESSIONS TO CUCURBIT YELLOW STUNTING DISORDER VIRUS

Cucurbit yellow stunting disorder virus (CYSDV)، a member of the genus Crinivirus (family Closteroviridae)، causes considerable losses in cucurbits. Using of the resistant cultivars is a potential option for control of the disease induced by CYSDV. In this research twenty five accessions of Cucumis melo، including local melons، collected from different regions in Iran، were evaluated under controlled conditions for their reaction to Iranian CYSDV isolate، (Bushehr). Inoculations were made at first true leaf-stage with Bemisia tabaci. Assays included mean of disease severity index 6 weeks after inoculation، time of symptoms development (infection percentages 20 days after inoculation) and virus concentration in plant (mean ELISA value 8 weeks after inoculation). Only two accessions Chorook zard and Til zard showed delay in symptom development، low disease severity index and low concentration of the virus. They were considered resistant to the virus and tolerant to the disease. The accessions Zard khareji، Zard moshabbak dorosht، Zard talaee and Sefid because of low concentration of the virus in ELISA and Sirjan and Kashefi because of delay in symptoms development were resistant to virus. Yazdi، Zard talaee، Sirjan، Zard moattar and Sefid had low disease severity index and rated tolerant. Other accessions were highly sensitive to the virus.