Unit of Plant Virology, Division of Plant Pathology, IARI, New Delhi-110012.
Tospoviruses are fast emerging as serious pathogens in India, affecting the cultivation of a wide range of field and horticultural crops. Following the identification of Tomato spotted wilt virus (TSWV), the sole member of the Tospovirus genus known at that time, as the causal agent of bud necrosis disease of groundnut in 1968, natural infection of TSWV was also established on several other leguminous and solanaceous hosts. Later in 1992, serological and nucleocapsid protein (N) gene sequence studies lead to the recognition of Groundnut bud necrosis virus (GBNV), a distinct Tospovirus species, as the causal agent of bud necrosis disease of groundnut. Subsequently, information on host range and N gene sequences revealed the prevalence of two distinct Tospoviruses, Watermelon bud necrosis virus (WBNV) originating from hosts within the Cucurbitaceae and GBNV from a more diverse group of plants within the Solanaceae and Fabaceae and others. Both GBNV and WBNV populations were least divergent, as the N and movement protein (NSm) genes originating from the Tospovirus isolates from different hosts and locations were highly conserved. Besides GBNV and WBNV, prevalence of two other Tospoviruses, Groundnut yellow spot virus from groundnut and Iris yellow spot virus from onion was recognised. Available evidences clearly suggest the lack of prevalence of TSWV in India.
