No abstract

Begomoviruses were detected in leaf samples of Sauropus androgynus (L.) Merr. plants showing leaf curling with or without yellowing symptoms in Kamphaeng Saen, Nakhon Pathom, Thailand in 2009 and 2010. From eight plants with symptoms, 17 complete begomoviral DNA‐As were amplified by polymerase chain reaction and sequenced. No DNA‐B was detected in any of the plants. All the DNA‐As had the characteristic begomovirus genome organization of six open reading frames, two in the virion‐sense orientation and four in the complementary orientation. Sequence comparison of these virus isolates indicated that one isolate belongs to Tomato leaf curl New Delhi virus, 12 isolates belong to Ageratum yellow vein virus and four isolates belong to a novel species with the tentative name Sauropus leaf curl virus. Five of the eight samples were found to be co‐infected by isolates of two different begomovirus species. Recombination analysis indicated that all but one of the isolates were probably the product of one or more recombination events. The results indicated that S. androgynus plants act as natural hosts as well as potential nurseries for genetic recombination between begomovirus species and strains.

Viral diseases are major constraints to tomato, cucumber and mung bean production in most areas where these crops are grown. To identify the viruses on the crops in Tajikistan, a field survey was conducted in 2019. Samples of cucumber, mung bean and tomato with virus-like symptoms were collected and the viruses present were diagnosed by RT-PCR and PCR. Across all the samples, a very high proportion of the samples were infected with viruses from the genera Cucumovirus and Potyvirus. Cucumber mosaic virus (CMV; Cucumovirus) was very common in the collected samples of the three crops. As for Potyvirus, Potato virus Y (PVY) was detected in the collected tomato samples, Zucchini yellow mosaic virus (ZYMV) was identified in the collected cucumber samples, and Bean common mosaic virus (BCMV) was detected in 53% of the mung bean samples. Over 68% of the collected samples were infected with two or more viruses, suggesting that mixed infections are common for the three crops. Due to the results that the most identified viruses for the three crops are transmitted by aphids, the management of aphids is extremely important for the production of tomato, cucumber and mung bean in Tajikistan.