National Key Laboratory of Crop Genetics and Germplasm Enhancement, National Center for Soybean Improvement, Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, Nanjing, China.
Provincial Key Laboratory of Agrobiology, Institute of Agro-biotechnology, Jiangsu Academy of Agriculture Sciences, Nanjing, China.
PLoS Genet. 2019 Jan 7;15(1):e1007798. doi: 10.1371/journal.pgen.1007798. eCollection 2019 Jan.
Salt stress is one of the major abiotic factors that affect the metabolism, growth and development of plants, and soybean [Glycine max (L.) Merr.] germination is sensitive to salt stress. Thus, to ensure the successful establishment and productivity of soybeans in saline soil, the genetic mechanisms of salt tolerance at the soybean germination stage need to be explored. In this study, a population of 184 recombinant inbred lines (RILs) was utilized to map quantitative trait loci (QTLs) related to salt tolerance. A major QTL related to salt tolerance at the soybean germination stage named qST-8 was closely linked with the marker Sat_162 and detected on chromosome 8. Interestingly, a genome-wide association study (GWAS) identified several single nucleotide polymorphisms (SNPs) significantly associated with salt tolerance in the same genetic region on chromosome 8. Resequencing, bioinformatics and gene expression analyses were implemented to identify the candidate gene Glyma.08g102000, which belongs to the cation diffusion facilitator (CDF) family and was named GmCDF1. Overexpression and RNA interference of GmCDF1 in soybean hairy roots resulted in increased sensitivity and tolerance to salt stress, respectively. This report provides the first demonstration that GmCDF1 negatively regulates salt tolerance by maintaining K+-Na+ homeostasis in soybean. In addition, GmCDF1 affected the expression of two ion homeostasis-associated genes, salt overly sensitive 1 (GmSOS1) and Na+/H+ exchanger 1 (GmNHX1), in transgenic hairy roots. Moreover, a haplotype analysis detected ten haplotypes of GmCDF1 in 31 soybean genotypes. A candidate-gene association analysis showed that two SNPs in GmCDF1 were significantly associated with salt tolerance and that Hap1 was more sensitive to salt stress than Hap2. The results demonstrated that the expression level of GmCDF1 was negatively correlated with salt tolerance in the 31 soybean accessions (r = -0.56, P < 0.01). Taken together, these results not only indicate that GmCDF1 plays a negative role in soybean salt tolerance but also help elucidate the molecular mechanisms of salt tolerance and accelerate the breeding of salt-tolerant soybean.
盐胁迫是影响植物代谢、生长和发育的主要非生物因素之一，大豆[Glycine max (L.) Merr.]萌发对盐胁迫敏感。因此，为了确保大豆在盐渍土壤中的成功建立和生产力，需要探索大豆萌发阶段耐盐的遗传机制。在这项研究中，利用 184 个重组自交系（RIL）群体来定位与耐盐性相关的数量性状位点（QTL）。一个与大豆萌发阶段耐盐性相关的主要 QTL 命名为 qST-8，它与标记 Sat_162 紧密连锁，位于第 8 号染色体上。有趣的是，全基因组关联研究（GWAS）在第 8 号染色体上同一遗传区域鉴定出几个与耐盐性显著相关的单核苷酸多态性（SNP）。重测序、生物信息学和基因表达分析用于鉴定候选基因 Glyma.08g102000，它属于阳离子扩散促进剂（CDF）家族，被命名为 GmCDF1。在大豆毛状根中过表达和 RNA 干扰 GmCDF1 分别导致对盐胁迫的敏感性增加和耐受性增加。本报告首次证明 GmCDF1 通过维持 K+-Na+ 内稳性来负调控大豆的耐盐性。此外，GmCDF1 影响转基因毛状根中两个离子稳态相关基因盐过度敏感 1（GmSOS1）和 Na+/H+ 交换器 1（GmNHX1）的表达。此外，单倍型分析在 31 个大豆基因型中检测到 GmCDF1 的 10 种单倍型。候选基因关联分析表明，GmCDF1 中的两个 SNP 与耐盐性显著相关，Hap1 比 Hap2 对盐胁迫更敏感。结果表明，在 31 个大豆品种中，GmCDF1 的表达水平与耐盐性呈负相关（r = -0.56，P < 0.01）。总之，这些结果不仅表明 GmCDF1 在大豆耐盐性中起负作用，还有助于阐明耐盐性的分子机制，并加速耐盐大豆的培育。
