Symptomatic and genetic characterization for soybean resistance to SDS foliar chlorosis. A, Typical SDS foliar symptoms observed in fields include interveinal chlorosis and necrosis. Severely impacted leaves also display leaf marginal curling and premature defoliation. B, Soybean varieties exhibited different SDS foliar symptoms. In response to phytotoxins produced by F. virguliforme, LD01-5907 displayed chlorosis while GD2422 displayed necrosis but no chlorosis. C, Linkage mapping using the RILs derived from GD2422 (no chlorosis) × LD01-5907 (chlorosis). One locus with seven SNPs was significantly associated with the SDS foliar chlorosis. The significant threshold was determined by permutation with 1,000 iterations at logarithm of the odds 3.5. The blue line and the blue bar indicate the 95% confidence interval of the Chlorosis locus without GmSGR markers. The green line and the green bar indicate the 95% confidence interval of the Chlorosis locus with GmSGR markers. D, Frequency distribution regarding the mean of SDS foliar chlorosis in the RIL population used in linkage mapping. E, Principal component analysis showed a scattered distribution for the germplasm accessions that exhibited resistance to SDS foliar chlorosis. Zero principal component was included to control population structure. F, Manhattan plot identified two SNPs, ss715580368 on Chr01 and ss715609614 on Chr11, at false discovery rate < 0.05 (green dots) and both exceeded the Bonferroni threshold (red horizontal line).