Genetic Analysis of “8101” Soybean Containing Three Genes for Resistance to Soybean Mosaic Virus

Soybean mosaic virus (SMV) occurs in most soybean [Glycine max (L.) Merr.] growing areas around the world. The use of soybean cultivars with resistance to SMV is the most effective way of controlling this disease. Three independent genetic loci (Rsv1, Rsv3, and Rsv4) with multiple alleles for SMV resistance have been identified. The objective of this study was to evaluate the genetic composition of a Chinese soybean line 8101 for SMV resistance. In this study, 8101 was crossed with susceptible cultivars Lee 68, Essex, and Hefeng No. 25. The genotype 8101 was also crossed with resistant lines PI 96983, L29, and V94-5152 carrying Rsv1, Rsv3, and Rsv4, respectively, to examine the allelic relationship between the genes in 8101 and the previously reported genes at these three loci. The results indicated that 8101 carries three independent dominant genes for resistance to SMV. One of them is at the Rsv1 locus but carries a different allele than the Rsv1 in PI 96983. This new allele confers resistance to SMV G1 but a susceptible reaction to SMV G7. The second gene is at the Rsv3 locus conferring resistance to SMV G7 but a susceptible reaction to SMV G1. The third gene is at the Rsv4 locus and confers resistance to both SMV G1 and G7. The presence of these three genes in 8101 confers resistance to SMV strains G1 through G3 and G5 through G7. The line 8101 is the first genotype identified as carrying all three SMV resistance genes, Rsv1, Rsv3, and Rsv4 Research is underway to further characterize the three resistance genes in 8101.