Table_4_Integration of Metabolomics and Transcriptomics for Investigating the Tolerance of Foxtail Millet (Setaria italica) to Atrazine Stress.XLSX

Foxtail millet (Setaria italica) is a monotypic species widely planted in China. However, residual atrazine, a commonly used maize herbicide, in soil, is a major abiotic stress to millet. Here, we investigated atrazine tolerance in millet based on the field experiments, then obtained an atrazine-resistant variety (Gongai2, GA2) and an atrazine-sensitive variety (Longgu31, LG31). To examine the effects of atrazine on genes and metabolites in millet plants, we compared the transcriptomic and metabolomic profiles between GA2 and LG31 seedling leaves. The results showed that 2,208 differentially expressed genes (DEGs; 501 upregulated, 1,707 downregulated) and 192 differentially expressed metabolites (DEMs; 82 upregulated, 110 downregulate) were identified in atrazine-treated GA2, while in atrazine-treated LG31, 1,773 DEGs (761 upregulated, 1,012 downregulated) and 215 DEMs (95 upregulated, 120 downregulated) were identified. The bioinformatics analysis of DEGs and DEMs showed that many biosynthetic metabolism pathways were significantly enriched in GA2 and LG31, such as glutathione metabolism (oxiglutatione, γ-glutamylcysteine; GSTU6, GSTU1, GSTF1), amino acid biosynthesis (L-cysteine, N-acetyl-L-glutamic acid; ArgB, GS, hisC, POX1), and phenylpropanoid biosynthesis [trans-5-o-(4-coumaroyl)shikimate; HST, C3′H]. Meanwhile, the co-expression analysis indicated that GA2 plants had enhanced atrazine tolerance owing to improved glutathione metabolism and proline biosynthesis, and the enrichment of scopoletin may help LG31 plants resist atrazine stress. Herein, we screened an atrazine-resistant millet variety and generated valuable information that may deepen our understanding of the complex molecular mechanism underlying the response to atrazine stress in millet.

谷子（Setaria italica）是一种在中国广泛种植的单型物种。然而，土壤中残留的莠去津（atrazine，一种常用玉米除草剂）是谷子面临的主要非生物胁迫。本研究基于田间试验探究了谷子对莠去津的耐受性，筛选得到抗莠去津品种‘Gongai2（GA2）’与莠去津敏感品种‘Longgu31（LG31）’。为解析莠去津对谷子植株基因及代谢物的影响，本研究比较了GA2与LG31幼苗叶片的转录组与代谢组谱。结果显示，经莠去津处理的GA2材料中鉴定得到2208个差异表达基因（differentially expressed genes, DEGs；其中上调501个，下调1707个）以及192个差异代谢物（differentially expressed metabolites, DEMs；其中上调82个，下调110个）；而经莠去津处理的LG31材料中则鉴定得到1773个DEGs（上调761个，下调1012个）以及215个DEMs（上调95个，下调120个）。对DEGs与DEMs的生物信息学分析表明，诸多生物合成代谢通路在GA2与LG31中显著富集，例如谷胱甘肽代谢（氧谷胱甘肽、γ-谷氨酰半胱氨酸；GSTU6、GSTU1、GSTF1）、氨基酸生物合成（L-半胱氨酸、N-乙酰-L-谷氨酸；ArgB、GS、hisC、POX1）以及苯丙烷类生物合成[反式-5-O-(4-香豆酰基)莽草酸；HST、C3′H]。同时，共表达分析结果显示，GA2植株可通过增强谷胱甘肽代谢与脯氨酸生物合成提升莠去津耐受性，而东莨菪内酯（scopoletin）的富集或可帮助LG31植株抵御莠去津胁迫。本研究筛选得到一个抗莠去津的谷子品种，并生成了极具价值的研究资料，有助于加深我们对谷子响应莠去津胁迫的复杂分子机制的理解。