Table_2_Subgenome-biased expression and functional diversification of a Na+/H+ antiporter homoeologs in salt tolerance of polyploid wheat.xlsx

Common wheat (Triticum aestivum, BBAADD) is an allohexaploid species combines the D genome from Ae. tauschii and with the AB genomes from tetraploid wheat (Triticum turgidum). Compared with tetraploid wheat, hexaploid wheat has wide-ranging adaptability to environmental adversity such as salt stress. However, little is known about the molecular basis underlying this trait. The plasma membrane Na+/H+ transporter Salt Overly Sensitive 1 (SOS1) is a key determinant of salt tolerance in plants. Here we show that the upregulation of TaSOS1 expression is positively correlated with salt tolerance variation in polyploid wheat. Furthermore, both transcriptional analysis and GUS staining on transgenic plants indicated TaSOS1-A and TaSOS1-B exhibited higher basal expression in roots and leaves in normal conditions and further up-regulated under salt stress; while TaSOS1-D showed markedly lower expression in roots and leaves under normal conditions, but significant up-regulated in roots but not leaves under salt stress. Moreover, transgenic studies in Arabidopsis demonstrate that three TaSOS1 homoeologs display different contribution to salt tolerance and TaSOS1-D plays the prominent role in salt stress. Our findings provide insights into the subgenomic homoeologs variation potential to broad adaptability of natural polyploidy wheat, which might effective for genetic improvement of salinity tolerance in wheat and other crops.

普通小麦（*Triticum aestivum*，BBAADD）是一种异源六倍体物种，其基因组整合了节节麦（Ae. tauschii）的D基因组与四倍体小麦（*Triticum turgidum*）的AB基因组。相较于四倍体小麦，六倍体小麦对盐胁迫等环境逆境具备更广泛的适应性。然而，该性状背后的分子基础尚未得到清晰阐释。质膜Na⁺/H⁺转运蛋白盐超敏感1（Salt Overly Sensitive 1, SOS1）是植物耐盐性的关键决定因子。本研究发现，TaSOS1的表达上调与多倍体小麦的耐盐性变异呈显著正相关。此外，转录组分析与转基因植株的GUS染色实验结果显示，TaSOS1-A与TaSOS1-B在正常培养条件下的根、叶中便具有较高的基础表达量，且在盐胁迫环境下其表达量进一步上调；而TaSOS1-D在正常条件下的根、叶中表达量显著较低，但在盐胁迫下其根部表达量显著上调，叶片则无明显变化。此外，拟南芥转基因功能验证实验表明，三个TaSOS1部分同源基因对耐盐性的贡献存在显著差异，其中TaSOS1-D在盐胁迫响应中发挥主导作用。本研究结果揭示了天然多倍体小麦亚基因组部分同源基因的变异对其广适性的潜在调控机制，可为小麦及其他作物的耐盐性遗传改良提供有效参考。