Evaluation Of Soybean Cultivars, 'Williams' Isogenic Lines, And Other Selected Soybean Lines For Resistance To Two Soybean Mosaic Virus Strains

Soybean mosaic virus (SMV) is one of the most common soybean viruses worldwide. The resistance or susceptibility of most commercial soybean cultivars to SMV is not known. The objectives of this study were to evaluate resistance to SMV strains G1 and G5 of current soybean cultivars, isogenic lines with different Rsv genes and alleles in 'Williams' or 'Williams 82' background, and selected soybean lines with reported or observed SMV resistance. Commercial and precommercial soybean cultivars were screened for resistance to SMV strains G1 and G5. Based on multiple tests, 1.5% and 6.7% of the 850 cultivars were resistant to SMV-G1 and SMV-G5, respectively. No cultivars were resistant to both strains. Expression of different SMV resistance genes in Williams isogenic lines inoculated with both SMV strains indicated that lines with Rsvl-y from 'Dorman', or unnamed resistance genes from 'Kosamame', and 'Sodendaizu', were resistant to G1 and susceptible to G5. Lines with Rsv1 alleles from PI 96983, 'Marshall', or `Ogden' were resistant to both strains, and lines with Rsvl alleles from `Raiden', `SS 74185' (P1486355), or 'Suweon 97' were resistant to G1 and produced a systemic necrosis reaction with G5. Lines with Rsv3-h from `Hardee' were susceptible to Gl and resistant to G5. Isogenic lines with SMV resistance genes from `Buffalo' showed either a resistant-resistant or resistant-susceptible reaction to the two SMV strains, suggesting the presence of more than one SMV resistance gene. Ten selected lines with reported or observed resistance to SMV were inoculated with the two SMV strains. Some lines were resistant to either G1 or G5, and some were resistant to both strains.