S-22. Co-infection or post-infection with KA22 DNA B ameliorates severe stunting and delay in flowering caused in Vigna mungo by Mungbean yellow mosaic virus-Vigna (MYMV-Vig) KA27 DNA B
Abstract
Mungbean yellow mosaic virus-Vigna (MYMV-Vig) is a bipartite Begomovirus that causes yellow mosaic disease in mungbean, blackgram, mothbean, soybean and pigeonpea. From field infected blackgram, one DNA A (KA30) and five different DNA B components (KA21, KA22, KA27, KA28 and KA30) were cloned and their infectivity was confirmed. KA27 DNA B had only 72% nucleotide sequence identity with KA22 DNA B. KA27 DNA B, along with KA30 DNAA caused severe stunting. In contrast, KA22 DNA B caused typical yellow mosaic symptom without causing severe stunting. Interestingly, co-infection of KA27 + KA22 DNA Bs along with the DNA A of MYMV-Vig resulted in amelioration from severe stunting. Post-infection with KA22 DNA B also resulted in the amelioration of severe stunting caused initially by KA27 DNA B. KA27 also caused an inordinate delay in flowering which was alleviated by co-infection or post-infection with KA22 DNA B. Although KA22 type of symptom was dominant over that of KA27 DNA B, there was no corresponding reduction in KA27 DNA B levels. It is proposed that movement protein (MP) and nuclear shuttle protein (NSP) of KA27 DNA B, but not those of KA22 DNA B, may interfere with developmental events and cause stunting by interacting with plant protein(s). Upon co-infection or post-infection with KA22 DNA B, MP or NSP of KA22 DNA B may interact more efficiently with the plant protein(s) and help in releasing them for their normal function. This might have resulted in the amelioration of severe stunting and in overcoming the delay in the onset of flowering.
