INHERITANCE OF RESISTANCE TO SOYBEAN MOSAIC-VIRUS IN BUFFALO AND HLS SOYBEAN

Soybean mosaic virus (SMV) is a major disease problem in soybean [Glycine max (L.) Merr.] production in several regions in the world. The disease is controllable with plant resistance. This study was undertaken to elucidate the genetics of SMV resistance in the cultivar Buffalo and in the breeding line HLS so they can be used effectively in breeding programs. Buffalo and HLS were crossed to the SMV-susceptible cultivar Jupiter and with each other. Portions of the F1, F2, and F2:3 populations from each cross were inoculated with one seven SMV strains (G1-G7). Virus inoculations were done in the field or greenhouse using an air-brush technique. Chi-square analysis of the segregation ratios of populations from the Buffalo x Jupiter cross show that Buffalo's resistance to SMV strains G1 to G7 is under monogenic control, and exhibited dominance under the conditions of this study. Results of the HLS x Jupiter cross show that resistance in HLS to SMV strains G5, G6, and G7 is also conditioned by a single dominant gene. When inoculated with SMV strain G5, G6, or G7, populations of F2 plants from the cross Buffalo x HLS segregated in the ratio of 15 resistant to 1 susceptible. This result, supported by the F2:3 segregation data, suggests that the SMV resistance genes in Buffalo and HLS are located at different loci.