Table_1_Genome-Wide Analysis of DREB Genes Identifies a Novel Salt Tolerance Gene in Wild Soybean (Glycine soja).XLSX

Salt stress is a major factor limiting the growth and yield of soybean (Glycine max). Wild soybeans (Glycine soja) contain high allelic diversity and beneficial alleles that can be re-introduced into domesticated soybeans to improve adaption to the environment. However, very few beneficial alleles have been identified from wild soybean. Here, we demonstrate that wild soybean is more salt tolerant than cultivated soybean and examine dehydration responsive element-binding (DREB) family transcription factor genes to look for advantageous alleles that might improve drought tolerance in cultivated soybean. Our genome-wide analysis identified 103 DREB genes from the Glycine max genome. By combined RNA-sequencing and population genetics of wild, landrace, and cultivated soybean accessions, we show that the natural variation in DREB3a and DREB3b is related to differences in salt tolerance in soybean accessions. Interestingly, DREB3b, but not DREB3a, appears to have undergone artificial selection. Soybean plants carrying the wild soybean DREB3b allele (DREB3b39Del) are more salt tolerant than those containing the reference genome allele (DREB3bRef). Together, our results suggest that the loss of the DREB3b39Del allele through domestication of cultivated soybean may be associated with a reduction in salt tolerance. Our findings provide crucial information for improving salt tolerance in soybean through molecular breeding.

盐胁迫是限制栽培大豆（Glycine max）生长与产量的主要非生物胁迫因子。野生大豆（Glycine soja）蕴含丰富的等位基因多样性与有益等位基因，可将其有益等位基因导入栽培大豆中，以提升栽培大豆的环境适应性。然而，目前从野生大豆中挖掘的有益等位基因数量极少。
本研究证实野生大豆的耐盐性优于栽培大豆，并针对脱水应答元件结合（dehydration responsive element-binding, DREB）家族转录因子基因，以期筛选可提升栽培大豆耐旱性的优势等位基因。
通过全基因组分析，我们从栽培大豆基因组中鉴定出103个DREB家族基因。结合野生种、地方品种与栽培大豆种质的转录组测序与群体遗传学分析，结果显示DREB3a与DREB3b的自然变异与不同大豆种质的耐盐性差异密切相关。
值得注意的是，DREB3b（而非DREB3a）似乎经历了人工选择。携带野生大豆DREB3b等位基因（DREB3b39Del）的大豆植株，其耐盐性显著高于携带参考基因组等位基因（DREB3bRef）的植株。
综上，本研究结果表明，栽培大豆驯化过程中DREB3b39Del等位基因的丢失，可能与栽培大豆耐盐性的下降相关。本研究成果为通过分子育种改良大豆耐盐性提供了关键的理论依据与遗传资源。