With the expanded application of heavy metal cadmium, soil cadmium pollution is more and more serious. In this study, using Salix matsudana as a phytoremediation candidate, we observed changes of gene expression and metabolic pathway after 1, 7 and 30 days under 2.5 mg/L and 50 mg/L cadmium stress. The result of transcriptome sequencing showed that we obtained 102 595 Unigenes; 26 623 and 32 154 differentially expressed genes (DEG) in the same concentration and different stress time; 8 550, 3 444 and 11 428 DEG with different concentrations at the same time; 25 genes closely related to cadmium stress response were screened. The changes of genes expression (such as metallothionein, ABC transporter, zinc and manganese transporter) depended on both concentration of cadmium and exposure time. The expression of several genes was obviously up-regulated after cadmium stress, for example 3,6-deoxyinosinone ketolase (ROT3) in brassinolide synthesis pathway and flavonoid synthase (FLS), flavanone-3-hydroxylase (F3H) in the synthesis pathway of brassinolide. In addition, GO analysis shows that GO entries were mainly enriched in metabolic processes including cellular processes, membranes, membrane fractions, cells, cellular fractions, catalytic activation and binding proteins in response to cadmium stress, whose number would increase along with cadmium concentration and exposure time. The reliability of transcriptome information was verified by qPCR and physiological experimental data. Response mechanisms of S. matsudana after cadmium stress were analyzed by transcriptome sequencing, which provided theoretical guidance for remediation of cadmium pollution in soil by S. matsudana.
随着重金属镉 (Cd) 应用范围的扩大，由此引发的土壤镉污染问题日益严重。以具有植物恢复潜力的旱柳Salix matsudana 作为研究对象，探究不同浓度的Cd (2.5 mg/L, 50 mg/L) 胁迫后旱柳无性系1 d、7 d 和30 d 后基因表达与代谢通路的变化。转录组测序结果表明：共获得102 595 个非冗余基因 (Unigenes)，相同浓度不同时间的差异基因总数为26 623 个和32 154 个；相同时间不同浓度的差异基因总数为8 550 个、3 444 个和11 428 个。从中筛选得到与Cd 胁迫响应密切相关的基因25 个，其中金属硫蛋白、ABC 转运蛋白、锌和锰转运蛋白等基因的表达不仅会随着Cd 胁迫浓度变化而且同时受到胁迫时间的改变而发生改变；油菜素内酯合成通路的ROT3 和黄酮类化合物合成通路的FLS、F3H 均明显上调。此外Cd 胁迫引起旱柳在代谢过程、细胞过程、膜、细胞器、细胞、细胞部分、催化活化和结合蛋白这8 个方面发生改变，参与这些GO 条目的差异表达基因数随着Cd 浓度和胁迫时间的增加而增加。并对转录组信息的可靠性用RT-PCR 和酶活性生理实验数据进行了验证。文中通过转录组测序分析旱柳Cd 胁迫后的响应机制，从而为旱柳修复土壤Cd 污染提供理论指导。.
Keywords: Salix matsudana; cadmium; differentially expressed genes; transcriptome.