Identification and validation of new sources of resistance for Mungbean Yellow Mosaic India Virus in urdbean [Vigna mungo (L.) Hepper]

Mungbean Yellow Mosaic India Virus (MYMIV) causes considerable damage to the susceptible urdbean cultivars or landraces wherever they are grown. To manage yellow mosaic disease caused by MYMIV, development of genetically resistant cultivars is strongly advisable. To identify a stable source for MYMIV resistance in urdbean a set of sixty-five advanced urdbean breeding lines/genotypes were screened under field conditions. MYMIV was confirmed by PCR assays in the symptomatic yellow mosaic leaves of urdbean genotypes. Based on the disease reactions genotypes were grouped into different categories. The average disease rating score recorded for test genotypes ranged from 1 to 6.16 as against 8.83 of YMD susceptible check (Co-5). Of the 65 test genotypes, 43 showed resistant reaction (1–2 scale) during all six years of testing against YMD. However, eight of them (IPU 10-1, IPU 96-6, IPU 99220, IPU 13-7, NP 21, PDU-3, IPU 13-3 and PLU 99–10) consistently showed resistant reaction (disease rating scale 1) with no visible symptoms on leaves indicating that these genotypes have stable resistance for MYMIV. Thirteen genotypes were identified as moderately resistant (disease rating score 3–4). Rest of the genotypes showed moderately susceptible to highly susceptible reactions (disease rating score 5–9). The identified MYMIV resistant urdbean genotypes can be used in yield evaluation trials in breeding programmes.