Identification of candidate genes for resistance to Soybean mosaic virus strain SC3 by using fine mapping and transcriptome analyses

This study is a continuation of our earlier reports on the identification and mapping of the Soybean mosaic virus (SMV) strain SC3 resistance gene present on chromosome 13 (LG F) of soybean (Glycine max (L.) Merr.). We used a combination of fine mapping and transcriptome sequencing to discover the candidate genes for SMV resistance in Qihuang-1. To fine-map the resistance gene, near-isogenic lines (NILs) from a cross between Qihuang-1 (resistant) and Nannong 1138-2 (susceptible) were genotyped with simple sequence repeats (SSR) and insertion and deletion (indel) markers to identify recombination events. Analysis of plants carrying key recombination events placed the resistance gene to a 180-kb region of the ‘Williams 82’ genome sequence with 17 annotated genes. Transcriptome and quantitative real-time PCR (qRT-PCR) analyses revealed that SMV resistance in Qihuang-1 was probably attributable to the four candidate genes (Glyma13g25920, Glyma13g25950, Glyma13g25970 and Glyma13g26000). The four candidate genes identified in this study can be used in further studies to investigate the role of resistance genes in conferring SC3 resistance in Qihuang-1.

G7H, a New Soybean mosaic virus Strain: Its Virulence and Nucleotide Sequence of CI Gene

A new Soybean mosaic virus (SMV) strain was isolated in Korea and designated as G7H. Its virulence on eight differentials and 42 Korean soybean cultivars was compared with existing SMV strains. G7H caused the same symptoms as G7 did on the eight differential cultivars. However, it caused different symptoms on the G7-immune Korean soybean cultivars; G7H caused necrosis in Suwon 97 (Hwangkeumkong) and Suwon 181 (Daewonkong), and a mosaic symptom in Miryang 41 (Duyoukong), while G7 caused only local lesions on those varieties. The nucleotide sequence of the cylindrical inclusion region of G7H was determined and compared with other SMV strains. G7H shared 96.3 and 91.3% nucleotide similarities with G2 and G7, respectively; whereas G7 shared 95.6% nucleotide similarity with G5H.