Infectivity analysis of two variable DNA B components ofMungbean yellow mosaic virus-Vigna inVigna mungo andVigna radiata

Abstract

Mungbean yellow mosaic virus-Vigna (MYMV-Vig), a Begomovirus that causes yellow mosaic disease, was cloned from field-infected blackgram (Vigna mungo). One DNA A clone (KA30) and five different DNA B clones (KA21, KA22, KA27, KA28 and KA34) were obtained. The sequence identity in the 150-nt common region (CR) between DNA A and DNA B was highest (95%) for KA22 DNA B and lowest (85.6%) for KA27 DNA B. The Rep-binding domain had three complete 11-nt (5'-TGTATCGGTGT-3') iterons in KA22 DNA B (and KA21, KA28 and KA34), while the first iteron in KA27 DNA B (5'-ATCGGTGT-3') had a 3-nt deletion. KA27 DNA B, which exhibited 93.9% CR sequence identity to the mungbean-infecting MYMV, also shared the 3-nt deletion in the first iteron besides having an 18-nt insertion between the third iteron and the conserved nonanucleotide. MYMV was found to be closely related to KA27 DNA B in amino acid sequence identity of BV1 (94.1%) and BC1 (97.6%) proteins and in the organization of nuclear localization signal (NLS), nuclear export signal (NES) and phosphorylation sites. Agroinoculation of blackgram (V. mungo) and mungbean (V. radiata) with partial dimers of KA27 and KA22 DNA Bs along with DNA A caused distinctly different symptoms. KA22 DNA B caused more intense yellow mosaic symptoms with high viral DNA titre in blackgram. In contrast, KA27 DNA B caused more intense yellow mosaic symptoms with high viral DNA titre in mungbean. Thus, DNA B of MYMVVig is an important determinant of host-range between V. mungo and V. radiata.

Emergence of a Latent Indian Cassava Mosaic Virus from Cassava Which Recovered from Infection by a Non-Persistent Sri Lankan Cassava Mosaic Virus

“…The fact that ICMV DNA A accumulated to high levels, regardless whether DNA B was present or not, while symptoms were much more severe upon agroinoculation with both DNAs, revealed that ICMV DNA B plays an important role in symptom development, which validates the earlier reports on symptom determination of bipartite begomoviruses [31,35,41]. The infectivity analysis of ICMV-[SeT4] in N. benthamiana plants proved that the isolate cloned from the CMD re-emergent cassava plants is infectious.…”

“…The probe DNA was labeled with [α- 32 P] deoxycytidine triphosphate (dCTP) using the Megaprime DNA labeling system (GE Healthcare UK Ltd.). Hybridization was carried out overnight at 65 °C followed by high stringency post hybridization washes [35]. …”

Infectivity analysis of a blackgram isolate of Mungbean yellow mosaic virus and genetic assortment with MYMIV in selective hosts

“…These are closely related to each other and to MYMIV (92%) than to MYMV. The second group is hypothesized to have emerged as a result of reassortment during mixed infection in a common host [8][9][10]. It is speculated that due to high percentage sequence identity in the CR ([75%) between these two virus species and the common hosts they infect, the MYMV …”

Antibegomoviral activity of the agrobacterial virulence protein VirE2

“…We report for the first time that geminivirus DNA accumulation is reduced in transgenic plants which expressed a TrAP mutant and the wild-type Agrobacterium VirE2. Vig] DNA A and DNA B caused the yellow mosaic disease in blackgram (Vigna mungo) [5] and mungbean [30].…”