Molecular characterization of soybean yellow mosaic virus isolates and identification of stable resistance sources in central India

In India, soybean production is predominant in central part of the country. Gradual increase in incidence of Yellow Mosaic Disease (YMD) is a major concern for soybean production in this region. Molecular characterization of virus infected samples collected from three different locations of central India, using coat protein (CP) gene specific primers revealed that all the three samples were infected with Mungbean Yellow Mosaic India Virus (MYMIV). Through sequence similarity and phylogenetic analyses, Jabalpur isolate of MYMIV (OM643233) was found to share maximum homology (up to 97.9%) with other isolates of MYMIV in India and across the world. Simultaneously, in another experiment, forty-seven agronomically superior soybean genotypes were evaluated for YMD resistance for four consecutive growing seasons (2017–2020) under hot-spot conditions at J.N.K.V.V., Jabalpur. Percent Disease Incidence (PDI) and symptoms severity grade (0–5) based Coefficient of Infection (CI) were employed in measuring the genotypic differences for YMD resistance. Friedman test indicated significant genotypic differences for PDI and CI, across four seasons. A BLUP (Best Linear Unbiased Prediction) based mixed model, WAASB (Weighted Average of Absolute Scores) and superiority index WAASBY (a combination of WAASB and Disease score) were employed on CI of yellow mosaic disease for identifying the stable and superior sources of resistance. Through WAASBY superiority index, out of forty seven genotypes, DS 3106 (WAASBY score = 93.90) was found to be superior with respect to stability and resistance, followed by SL 955 (WAASBY score = 90.08) and JS 21–75 (WAASBY score = 78.21). Through cluster analysis, based on PDI and CI, DS 3106, SL 955 and JS 21–75 were grouped together. Hence, these three genotypes can be employed as candidate resistant sources in breeding for high yielding and YMD resistant varieties suitable for cultivation in central India. Through Pearson’s correlation analysis, CI was found to be positively correlated with WFP (Whitefly Population) (r = 0.91^*) and atmospheric mean temperature (r = 0.77), indicating the role of the vector and weather variables in aggravating the disease severity.