转录组及代谢组联合解析胡麻根部对盐胁迫的响应机制

Conjoint transcriptome and metabolome analysis of the response mechanism of flax root to salt stress

通过“广靶代谢组+转录组”联合分析方法,对NaCl胁迫下胡麻(Linure usitatissmum)耐盐种质资源R40和敏感资源R24根部差异表达基因与差异积累代谢物进行共表达分析,以探明代谢物与关键基因的协同变化情况,阐明胡麻的耐盐代谢过程和变化规律,发掘胡麻中可能调控抗盐代谢途径的重要基因。共鉴定出具有显著差异的代谢物741个,其中下调409个,上调332个,鉴定出差异表达基因30233条,其中上调15827条,下调14406条,有注释结果的转录因子13015个。富集前十的代谢物几乎都有相对应的功能转录因子富集,如黄酮和黄酮醇的生物合成、苯丙素的生物合成、氨基糖和核苷酸糖的代谢、花青素生物合成、类黄酮生物合成等通路均有对应的转录因子参与其中。胡麻根部在盐胁迫下调控抗盐代谢途径的重要基因主要以参与调控糖类代谢为主,增强细胞的渗透压,从而有效降低盐碱胁迫的伤害;筛选出的8个候选基因与5个代谢物具有明显的相关性,每一个代谢物与一个或多个基因相关联,色氨酸–生长素通路发现,GH3基因是一种典型的与植物生长素原初反应相关的基因,在植物的抗逆防卫反应中起重要作用。

In this study,a co-expression analysis of differentially expressed genes and differentially accumulated metabolites in the roots of salt-tolerant(R40)and salt-sensitive flax germplasm(R24)under NaCl stress was conducted through conjoint analysis of the broad-target metabolome and transcriptome.This could help to understand the coordinated variations in the metabolome and key genes,to elucidate the metabolic process and the associated changes in flax under salt stress,and ultimately to identify the important flax genes that might regulate the metabolic pathways related to salt resistance.Here,we identified 741 metabolites with significant differences,including 409 downregulated and 332 upregulated metabolites.We also identified 30233 differentially expression genes including 15827 upregulated genes and 14406 downregulated genes,of which 13015 transcription factors were annotated.Almost all of the top ten metabolites were enriched with the corresponding functional transcription factors.For example,corresponding transcription factors are involved in flavonoid and flavonol biosynthesis,phenylpropanoid biosynthesis,amino sugar and nucleotide sugar metabolism,anthocyanin biosynthesis,flavonoid biosynthesis,and other pathways.The important genes of flax roots regulating salt resistance metabolism under salt stress are mainly involved in regulating sugar metabolism,thus effectively reducing the damage caused by saline-alkali stress by enhancing the osmotic pressure of cells.In the present study,eight candidate genes were significantly correlated with five metabolites,and each metabolite was associated with one or more genes.In addition,the GH3 gene found in the tryptophan-auxin pathway is a typical gene correlated with the primary reaction of auxin and plays important roles in stress resistance and defense responses.