Cucurbit-infecting viruses in Brazil

Abstract

Cucurbit crops are grown throughout many Brazilian states and are affected by several viral diseases that represent one of the main constraints to cucurbit production in the country causing severe economic losses. During 2008-2015, a survey was performed in open-field of watermelon (Citrullus lanatus), melon (Cucumis melo), cucumber (C. sativus), pumpkin (Cucurbita spp.), chayote (Sechium edule), and gherkin (C. anguria) crops to determine distribution and relative incidence of six viruses. More than 1050 leaf samples were collected from plants showing virus-like symptoms in more than 20 counties of eight Brazilian states (Goias, Bahia, Sao Paulo, Alagoas, Pernambuco, Ceara, Rio Grande do Norte, and Maranhao) and the Federal District. Samples were screened by dot-ELISA or DAS-ELISA tests using polyclonal antibodies to investigate the occurrence of Papaya ringspot virus-type watermelon (PRSV-W), Watermelon mosaic virus (WMV), Zucchini yellow mosaic virus (ZYMV), Cucumber mosaic virus (CMV), Zucchini lethal chlorosis virus (ZLCV), and Melon yellowing-associated virus (MYaV). In addition, total DNA obtained from leaf samples was tested for geminivirus infections by PCR using a pair of universal primers. Serological tests results indicated that approximately 60% of the samples were infected with at least one of the viruses tested. PRSV-W (40.89%) and ZYMV (25.46%) were the most prevalent viruses detected in all cucurbit species. WMV and CMV were found at low percentage in the leaf samples, 8.76 and 5.02%, respectively. MYaV (22.46%) occurred mainly in melon, while ZLCV (18.11%) was detected mostly infecting watermelon and pumpkins. The occurrence of mixed infection was observed in 17.41% of the leaf samples, especially in combination with PRSV-W. None of the samples tested positive for geminivirus infection by PCR. These data confirm the economic importance of cucurbit-infecting viruses in different Brazilian regions.