Association of grapevine geminivirus a isolate QN with upward leaf curling, necrosis, chlorosis, and malformation symptoms in two grapevine cultivars

Abstract

Grapevine geminivirus A (GGVA) is a recently identified DNA virus that infects grapevine, but its pathogenicity is not well studied. Previously, we investigated the pathogenicity of the new GGVA isolate QN (GGVA^QN) on grapevine ‘Red Globe’ plants. In this study, grapevine ‘Red Globe’ and ‘Summer Black’ plants were inoculated with GGVA^QN and grown without artificial control of temperature and light, and all of them exhibited upward leaf curling. This symptom was also found in field-grown grapevine ‘Shine Muscat’ plants infected with multiple grapevine viruses, including GGVA (isolate SM) (2,905 nt, sharing 97.69% genome sequence identity with GGVA^QN), and in the upper developed leaves of previously GGVA^QN-inoculated ‘Red Globe’ plants one week after they were moved from artificial to natural lighting. The upward leaf curling symptom was similar to that observed previously in Nicotiana benthamiana plants inoculated with GGVA^QN, in field-grown grapevine ‘Queen Nina’ plants, and in in vitro-grown grapevine ‘Marselan’ plantlets, from which GGVA^QN and GGVA^ML isolates with identical genome sequences were obtained. In addition to upward leaf curling, malformation, chlorosis, and necrosis symptoms were also observed on all GGVA^QN-inoculated ‘Red Globe’ and ‘Summer Black’ plants. The findings presented here suggest that GGVA^QN is closely associated with severe foliar symptoms in grapevine ‘Red Globe’ and ‘Summer Black’ cultivars and emphasize the need to control the virus.