Characterization of Resistance to Soybean mosaic virus in Diverse Soybean Germplasm

Abstract

Soybean mosaic virus (SMV) causes one of the most destructive viral diseases in soybean [Glycine max (L.) Merr.] worldwide. Ninety‐eight SMV isolates identified in the USA have been classified into seven strain groups (G1–G7). Three independent loci (Rsv1, Rsv3, and Rsv4) have been identified for SMV resistance. Multiple resistance alleles have been reported for the Rsv1 and Rsv3 locus. The objective of this research was to group diverse soybean genotypes on the basis of their differential reactions to SMV strains. SMV strains G1 and G7 were used to characterize the reactions of 212 soybean genotypes to SMV. Fifty‐five genotypes were resistant to G1 but susceptible to G7, and virus was detected in G7‐inoculated plants. Thirty‐one genotypes were resistant to G1 but exhibited stem‐tip necrosis following G7 inoculation. These 86 soybean genotypes presumably carry alleles at the Rsv1 locus. Thirty‐seven genotypes were resistant to G1 and G7, and SMV was not detected by ELISA, indicating that they probably carry Rsv4, Rsv1‐r, or Rsv1‐h or a combination of two resistance genes Rsv1Rsv3, Rsv1Rsv4, or Rsv3Rsv4. Seven genotypes were susceptible to G1 but resistant to G7 and may carry alleles at the Rsv3 locus. PI 507389 and PI 61944 developed stem‐tip necrosis after inoculation with G1 and a mosaic symptom when inoculated with G7, indicating that PI 61944 may carry the same Rsv1‐n gene as PI 507389. Eighty soybean accessions developed mosaic symptoms when inoculated with G1 or G7 because of the lack of SMV resistance genes. The information from this research will be helpful in selecting SMV‐resistant parents for crossing in a breeding program.