Molecular epidemiology on seasonal variation of Yellow mosaic disease incidence in blackgram vigna mungo l Hepper and its management through Exogenous delivery of dsrna

Abstract

newline The yellow mosaic disease (YMD) of blackgram caused by Mungbean yellow newlinemosaic virus has emerged as a serious threat to blackgram production especially in the newlineSouth East Asia. The major emphasis of the present study was to develop agroinfectious newlineclone of MYMV; to study the molecular epidemiology of MYMV and devising a newlinemanagement strategy for MYMV through exogenous delivery of double stranded RNA. newlineLeaves of blackgram displaying characteristic yellow mosaic symptoms were collected newlinefrom Vamban (Pudukottai) during kharif 2017. The DNA of the Vamban isolate of newlineMYMV was subjected to Rolling circle amplification (RCA). The RCA product was newlinecloned in pUC 18 vector and the pUC 18 DNA A and DNA B clones were sequenced by newlinethe primer walk method. The full length genome sequences of pUC 18 DNA A clone newline(pMYA-H14) and pUC 18 B clone DNA B clone (pMYB-B12) were deposited in the newlineNCBI database (MW436692 and MZ130506). The genome organisation of DNA A newline(pMYA-H14) showed to be encoding two open reading frames on viral sense of the newlinegenome, while the remaining four ORFs were found to be on the complementary strand. newlineIn the case of DNA B (pMYB-B12), ORF BV1 was found to be encoded by viral sense newlinestrand while ORF BCI on the complementary strand. The phylogenetic analysis and the newlineper cent similarity index of DNA A (pMYA-H14) with other begomoviruses revealed a newlinemaximum identity of 98.2 per cent with MYMV blackgram isolate of Coimbatore newline(KC911721.1) and DNA B (pMYB-B12) had a maximum identity of 96.4 per cent with newlineMYMV blackgram Vamban isolate (DQ400849.1). newlineThe agroinfectious clones of MYMV Vamban isolate were developed by newlineincorporation of partial tandem repeats of DNA A (pMYA-H14) and DNA B (pMYBB12) newlineinto Agrobacterium followed by agroinoculation into a MYMV susceptible CO-5 newlinevariety of blackgram. The YMD symptoms were absent on agroinoculated plants even at newline60 days after agroinoculation and the PCR analysis with MYMV specific primers was newlinealso found to be negative. The low identity of 90 per cent between the common regions newlineof DNA