Soybean mosaic virus (SMV) affects seed quality and production of soybean (Glycine max (L.) Merr.) worldwide.  SC18 is one of the dominant SMV strains in South China, and accession Zhonghuang 24 displayed resistance to SC18.  The F₁, F₂ and 168 F₁₁ recombinant inbred lines (RILs) population derived from a hybridization between Zhonghuang 24 (resistant, R) and Huaxia 3 (susceptible, S) were used in this study.  According to the segregation ratios of the F₂ generation (3R:1S) and the recombinant inbred lines (RILs) population (1R:1S), one dominant locus may regulate the resistance to SC18 in Zhonghuang 24.  By using composite interval mapping (CIM), Rsc18 was mapped to a 415.357-kb region on chromosome 13.  Three candidate genes, including one NBS-LRR type gene and two serine/threonine protein type genes, were identified according to the genetic annotations, which may be related to the resistance to SC18.  The qRT-PCR demonstrated that these genes were up-regulated in the R genotype compared to the control.  In conclusion, the findings of this research enhanced the understanding about the R genes at the Rsc18 locus.  Moreover, our results will provide insights for designing molecular markers to improve marker-assisted selection and developing new varieties with resistance to SC18.

Pod shattering is an important domesticated trait which can cause great economic loss of crop yield in cultivated soybean.  In this study, we utilized two recombinant inbred line populations (RILs, CY, Huachun 2×Wayao; GB, Guizao 1×B13) to identify quantitative trait loci (QTLs) associated with pod shattering in soybean across multiple environments.  A total of 14 QTLs for pod shattering were identified in the two RIL populations, which had LOD scores ranging from 2.64 to 44.33 with phenotypic variance explanation (PVE) ranging from 1.33 to 50.85%.  One QTL qPS16-1, located on chromosome 16, included a well-known functional gene Pod dehiscence 1 (Pdh1) that was reported previously.  Ten new putative QTLs were validated in two RIL populations, and their LOD scores were between 2.55 and 4.24, explaining 1.33 to 2.60% of the phenotypic variation.  Of which four novel QTLs (qPS01-1, qPS03-2, qPS05-1, and qPS07-1) could be detected in two environments where nine genes had specific changes in gene expression.  Although the nine genes may have significant effects on pod shattering of soybean, their detailed functions still need to be further explored in the future.  The results of this study will facilitate a better understanding of the genetic basis of the pod shattering-resistant trait and benefit soybean molecular breeding for improving pod shattering resistance