Diagnosis of symptomless Yellow mosaic begomovirus infection in pigeonpea by using cloned Mungbean yellow mosaic India virus as probe

One isolate of Mungbean yellow mosaic India virus (MYMIV) of mungbean plants from Sri Ganganagar, Rajasthan, designated as MYMIV-Mg was isolated and DNA-A and DNA-B, the two full length bipartite genomic components of this virus, were cloned. The [alpha-P-32] labeled diagnostic probes specific to these cloned DNA-A and -B of MYMIV-Mg were used to detect the virus infection in infected plants by nucleic acid spot hybridization (NASH) test. The NASH tests detected the MYMIV infection and concentration of viral titre in susceptible, moderately susceptible, resistant and symptomless genotypes of pigeonpea (Cajanus cajan) plants. Fourteen genotypes of pigeonpea were tested against five naturally occurring MYMIV variants viz., MYMIV-Bg, -MgD, -MoL, -Mg and -Pp1 through viruliferous whitefly (Bemisia tabaci) transmission in greenhouse condition. Disease incidence and severity of MYMIV in different pigeonpea genotypes varied with the variants of MYMIV. Many genotypes of pigeonpea did not produce visible yellow mosaic symptoms after inoculation with MYMIV variants MYMIV-Bg, -MbD and -MoL, although, majority of the symptomless genotypes were found to be infected by MYMIV, as viral DNA was detected by NASH test.