Detection and molecular characterization of viruses associated with tomato yellow leaf curl disease in cucurbit crops in Jordan

In this study, Tomato yellow leaf curl Sardinia virus (TYLCSV) and the strains Israel and Mild of Tomato yellow leaf curl virus (TYLCV-IL, TYLCV-Mld) were detected for the first time in four cucurbit crops in Jordan by nested polymerase chain reaction (nPCR). These viruses cause the tomato yellow leaf curl disease (TYLCD) in tomato. Cucumber, squash, melon and watermelon plants inoculated with TYLCV-IL[JO:Cuc], TYLCV-Mld, TYLCSV-IT[IT:Sar:88] and the Jordanian isolate of TYLCV (TYLCV-JV) did not show disease symptoms. However, virus-specific fragments were detected in uppermost leaves of symptomless plants by nPCR. A whitefly transmission test showed that Bemisia tabaci could transmit TYLCV-Mld from cucumber into tomato and jimsonweed plants. However, all infected tomato plants remained symptomless. In addition, results of semi-quantitative PCR (sqPCR) analysis showed that the relative amount of TYLCV-Mld DNA acquired by B. tabaci from cucumber plants was less than that acquired from tomato plants.