Integrating Field Screening and Molecular Diagnostics to Assess Yellow Mosaic Disease Resistance in Selected Mungbean...

Yellow mosaic disease (YMD) remains the most destructive viral threat to mungbean production in India, with increasing reports of resistance erosion in several released cultivars. Because earlier screening efforts rarely confirmed the identity of the infecting begomovirus, the stability of resistance under current mungbean yellow mosaic India virus (MYMIV) pressure remains uncertain. This study re-evaluated the resistance status of 30 released mungbean cultivars across four environments: Summer 2024, Summer 2025, Kharif 2024, and Kharif 2025, under natural epiphytotic conditions at Kanpur. Disease incidence (PDI) and severity (PDS) were recorded at maturity, and genotypes were categorized for resistance. Species-specific PCR assays confirmed MYMIV as the sole causal agent in all evaluated symptomatic samples of susceptible check DGGV2, and full-length DNA-A and DNA-B sequencing validated four MYMIV isolates consistently associated with field infections. Multi-environment ANOVA revealed significant effects of both genotype and environment for PDI and PDS. Several cultivars including GM-6, ML-131, SML-668, Pusa-9531, Pusa M-0672, MH-1142, IPM 2-3, IPM 205-7, and Shalimar Mung-2 exhibited consistently low disease expression, indicating stable and durable resistance to MYMIV. In contrast, cultivars such as HUM-16, Co-8, IPM 99-125, IPM 512-1, and Pusa-Ratna showed higher environmental sensitivity. Factor analysis of mixed data and Random Forest classification (100% accuracy) robustly separated resistant and moderately resistant genotypes, with PDS emerging as the key discriminatory trait. Conclusively, the study provides a MYMIV-validated, multi-season reassessment of varietal performance and identifies reliable donor lines for resistance breeding and further multi-location validation under MYMIV pressure.