Genetic Analysis of Resistance to Soybean Mosaic Virus In PI61947.

The soybean line PI61947 from Korea has shown resistance to Soybean mosaic virus (SMV), one of the most destructive soybean viral diseases. PI61947 exhibits a unique pattern of SMV reaction as compared to the standard differential cultivars, thus may contain a new gene or allele for SMV resistance.  The objectives of this research were to investigate the inheritance of SMV resistance in PI61947 and the genetic relationship of the resistance genes with other reported genes. PI61947 was crossed to Essex (rsv), PI96983 (Rsv1), L29 (Rsv3), and V94-5152 (Rsv4) to generate genetic populations for the study. The F₂ and F_2:3 populations from each cross were inoculated with SMV strain G7 in the greenhouse. Inoculated plants were monitored weekly for SMV reaction and classified as resistant, necrotic, or mosaic. Tissue blotting assay, a serological test, was used to verify the virus infection. Chi-square tests were performed in the F₂ and F_2:3 populations for goodness-of-fit to expected genetic ratios. Results revealed that PI61947 contains a single gene conferring resistance to SMV and that this gene is a new allele at the Rsv1 locus. The F₂ population from the cross PI61947 x Essex has been screened using a PCR-based gene specific marker Rsv1f-r. Preliminary analysis of the molecular data supports the conclusions drawn from phenotypic screening.