Transcriptomic and Co-Expression Network ProfilingReveal Biological Mechanism of Response to Salt Stress in Wheat(Triticum aestivum L.)

As one of the main food crops in the world, the yield of wheat seriously affects the world food security. However, the increasing salinization of the soil severely affects the production yield. Therefore, breeding of salt-tolerant wheat cultivars is of great significance to guarantee food security facing soil salinization. To reveal biological mechanism of response to salt stress in wheat, we selected CM6005 with typical salt tolerance and KN9204 with a typical salt sensitive as experimental material. These two varieties were cultivated in soil with salt content of 1 %(CK) and 5 %(salt-treatment), respectively. Leaf was sampled at 7 and 14 days after treatment. Comparing with the control, two varieties showed significant difference under salt treatment. The results of RNAseq analysis showed that salt-response DEGs of two varieties at bud stage markedly more than seedling stage, indicating that bud stage was more sensitive to salt stress.We divided all DEGs into five types, including common DEGs, specific DEGs in CM6005, specific DEGs in KN9204, DEGs based on relative changes and DEGs with opposite trends. Through enrichment analysis for each type DEG, we found that common salt tolerance mechanism for two varieties such as amino acid transmembrane transport (GO:0003333), glucose transmembrane transport (GO:1904659), thiamine metabolism (ko00730) and so on. The variety-specific salt tolerance mechanisms were also found, which showed a clear distinction between two varieties. Finally, we identified genes modules and screening hub genes related to salt tolerance using WGCNA method. These hub genes could play core roles in gene expression network of salt tolerance. The findings in this study would greatly promote molecular breeding of salt-tolerant wheat, especially for genetic improvement based on CM6005 and KN9204.

小麦作为全球主要粮食作物之一，其产量严重影响世界粮食安全。然而日益加剧的土壤盐渍化正严重制约小麦生产。因此，培育耐盐小麦品种对于应对土壤盐渍化、保障粮食安全具有重要意义。为揭示小麦响应盐胁迫的生物学机制，本研究选取典型耐盐品种CM6005与典型盐敏感品种KN9204作为实验材料。将两个品种分别种植于盐分含量1%（对照组，CK）和5%的盐处理土壤中，并于处理后第7天和第14天采集叶片样本。与对照组相比，两个品种在盐处理下均表现出显著差异。RNAseq分析结果显示，两个品种在芽期的盐响应差异表达基因（Differentially Expressed Genes, DEGs）数量显著多于苗期，表明芽期对盐胁迫更为敏感。本研究将所有差异表达基因划分为5类，包括共同差异表达基因、CM6005特异性差异表达基因、KN9204特异性差异表达基因、基于相对表达变化的差异表达基因以及表达趋势相反的差异表达基因。通过对每类差异表达基因进行富集分析，发现两个品种共享的耐盐机制包括氨基酸跨膜运输（GO:0003333）、葡萄糖跨膜运输（GO:1904659）、硫胺素代谢（ko00730）等。同时还鉴定出品种特异性的耐盐机制，二者之间呈现出清晰的差异。最后，本研究通过加权基因共表达网络分析（Weighted Gene Co-expression Network Analysis, WGCNA）鉴定得到基因模块，并筛选出与耐盐相关的核心基因（hub genes）。这些核心基因在耐盐基因表达网络中发挥核心调控作用。本研究结果将极大推动耐盐小麦的分子育种工作，尤其是基于CM6005和KN9204的遗传改良。