Survey for Yellow Mosaic Disease Occurring on Blackgram [Vigna mungo (L.) Hepper] and Weed Hosts in Four Major Blackgram Growing Districts of Andhra Pradesh and Characterization of Associated Viruses using Coat Protein Gene

Abstract

Background: Yellow mosaic disease (YMD) caused by Yellow mosaic virus is one of the major constraints in the pulse production in Andhra Pradesh (A.P.) due to fast evolution of strains, like Mungbean yellow mosaic India virus (MYMIV). Keeping this in view, a survey was undertaken in the major blackgram growing districts of A.P. to know the YMD incidence in blackgram and weed hosts and were characterized based on genetic features by comparing with other YMV isolates from different hosts and locations across the world. Methods: Roving survey was conducted during rabi 2019-20 in major blackgram growing districts of A.P. viz., Krishna, Guntur, West Godavari and Prakasam districts for YMD incidence. Blackgram plants showing characteristic symptoms were collected as representative samples from each mandal along with the suspected weed plants and were subjected to amplification using coat protein (CP) specific primers followed by molecular characterization. Phylogenetic tree for coat protein (CP) gene was constructed using aligned sequences with 1000 bootstrap replicates following neighbor-joining phylogeny. Result: Out of the four districts surveyed, the highest disease incidence was recorded at Machavaram village of Prakasam district (43.22%), whereas least disease incidence was recorded at Chinaganjam village of Praksam district (2.4%). Six weeds viz., Ageratum conyzoides, Amaranthus viridis, Parthenium hysterophporus, Vigna trilobata, Abelmoscus moschatus, Desmodium laxiflorum have showed positive result in PCR amplification with MYMIV specific coat protein primers. Four isolates from blackgram samples and two from weed plants shared 94.85 to 99.58% nucleotide identity among themselves.