Fine mapping and analyses of the RSC15ZH resistance candidate gene for the soybean mosaic virus

The soybean mosaic virus (SMV) is a viral pathogen caused by Potyvirus reported in the major soybean growing areas of the world. SMV strain SC-15 is the most virulent and predominant strain that infects all soybean differentials and is widely distributed throughout southern China. In this study, three elite SMV-resistant soybean varieties that possess better comprehensive traits were identified through a screening test. A mapping population containing 163 F-8 recombinant inbred lines derived from a Zhonghuang24 (resistant) x Huaxia3 (susceptible) cross was used to locate the resistance gene for SMV strain SC-15. A high-density genetic linkage map was developed containing 2639 recombination bins using the restriction site-associated DNA sequencing (RAD-seq) method. Results revealed a novel resistance gene, R(SC15)ZH identified in a 63 kb region of chromosome 13. This locus was further characterized by quantitative real-time PCR (qRT-PCR). Four candidate resistance genes were identified that were possibly involved in regulating SMV resistance, especially Glyma13g24461. These results provide a basic foundation for soybean breeding programs to improve resistance to SMV strain SC-15 and for positional cloning of SMV resistant candidate genes.