Mungbean necrosis disease caused by a strain of Groundnut bud necrosis virus

Abstract

Tospovirus infection on mungbean (up to 70%) was noticed at Indian Agricultural Research Institute experimental farm, New Delhi in different varietal trials. Symptoms under field conditions included necrosis of plant parts such as leaves, stems, petioles, growing points, buds and pods. Symptomatic mungbean plants showed positive reaction with Groundnut bud necrosis virus (GBNV) and Watermelon silver mottle virus (WSMV) antisera in direct antigen-coated enzyme-linked immunosorbent assay. Mungbean Tospovirus was easily transmitted to cowpea cv. Pusa Komal, which could be used as a diagnostic host. The virus was also mechanically transmitted to different plant species belonging to families Fabaceae, Cucurbitaceae, and Solanaceae. The nucleocapsid protein (N) gene of the virus was amplified, cloned and sequenced (GenBank Accession number AF515818). The sequenced region contained an ORF of 831 nucleotides that could potentially code for N protein of 276 amino acids. Comparative sequence analyses revealed that the N gene shared 97% and 99% sequence identity with GBNV at nucleotide and amino acids levels respectively, suggesting the Tospovirus isolate from mungbean to be a strain of GBNV.