Inheritance of a Resistance to Soybean Mosaic Virus In PI399091.

Soybean mosaic virus (SMV) is an important soybean viral disease worldwide. Different SMV isolates are classified into seven distinct groups, G1 through G7. Currently, there are three loci associated with SMV resistance including, Rsv1, Rsv3, and Rsv4.  PI399091 shows a different pattern in response to SMV strains compared to other resistant cultivars. The hypothesis of this study is that PI399091 may contain a new gene or allele conferring resistance to SMV.  PI399091 was crossed with Essex, a susceptible cultivar, and the progeny were inoculated with SMV strain G7 in the greenhouse to determine the inheritance of resistance gene(s). The SMV data was recorded weekly based on the plant reaction as resistant(R), necrotic (N), or susceptible (S). To detect of the virus in the infected plant, a tissue blotting assay, a serological test, was used. To study the allelomorphic relationships, PI399091 was crossed with PI96983 (Rsv1), L29 (Rsv3), and V94-5152(Rsv4). The F₂ and F_2:3 populations were inoculated with SMV strain G7.  The chi-squared analysis in the F₂ and F_2:3 populations confirm the presence of a single resistance gene in PI399091. Allelism tests showed that the SMV resistance gene in PI399091 is a new allele at the Rsv3 locus.