Diversity of tospoviruses infecting vegetable crops of eastern Indo-Gangetic plains of Uttar Pradesh and its impact on cowpea seed health

Abstract

Major vegetable growing areas in the eastern Indo-Gangetic plains of Uttar Pradesh were studied for the prevalence of tospoviruses over 5 years from 2015 to 2019. A total of 161 samples from 13 cultivated, one wild, and two weed species across five cropping seasons were carefully examined to identify the diversity and possible potential reservoirs of tospoviruses in the vegetable ecosystem. The results indicate that GBNV was mainly distributed in solanaceous crops, whereas WBNV in cucurbitaceous crops. Among weeds, datura and night shade were identified as an alternative host, which could have contributed to the epidemiology of tospovirus. In addition to some earlier reported hosts, WBNV in long melon was documented for the first time from India. Interestingly, GBNV and WBNV viruses were identified to co-infect bitter gourd plants. Phylogenetic analysis based on the N gene illustrated the monophyletic nature of GBNV and CaCV. In contrast, WBNV isolates were segregated into two diferent subclad comprising the northern and southern Indian isolates. Furthermore, cowpea seeds from infected plants were taken to determine GBNV infection’s ill-efects on seed quality. The study revealed germination percentage, seed weight, vigour index, percentage of abnormal seedlings, and seed yield per plant were significantly reduced in infected seeds compared to healthy ones. However, there was no significant difference in the speed of seed germination