Table_1_SaHsfA4c From Sedum alfredii Hance Enhances Cadmium Tolerance by Regulating ROS-Scavenger Activities and Heat Shock Proteins Expression.xlsx

The heat shock transcription factor (Hsf) family, an important member in plant stress response, affects cadmium (Cd) tolerance in plants. In this study, we identified and functionally characterized a transcript of the Hsf A4 subgroup from Sedum alfredii. Designated as SaHsfA4c, the open reading frame was 1,302 bp long and encoded a putative protein of 433 amino acids containing a complete DNA-binding domain (DBD). Heterologous expression of SaHsfA4c in yeast enhanced Cd stress tolerance and accumulation, whereas expression of the alternatively spliced transcript InSaHsfA4c which contained an intron and harbored an incomplete DBD, resulted in relatively poor Cd stress tolerance and low Cd accumulation in transgenic yeast. The function of SaHsfA4c under Cd stress was characterized in transgenic Arabidopsis and non-hyperaccumulation ecotype S. alfredii. SaHsfA4c was able to rescue the Cd sensitivity of the Arabidopsis athsfa4c mutant. SaHsfA4c reduced reactive oxygen species (ROS) accumulation and increased the expression of ROS-scavenging enzyme genes and Hsps in transgenic lines. The present results suggest that SaHsfA4c increases plant resistance to stress by up-regulating the activities of ROS-scavenging enzyme and the expression of Hsps.

热激转录因子（heat shock transcription factor, Hsf）家族是植物胁迫响应中的重要成员，可调控植物对镉（cadmium, Cd）的耐受性。本研究从东南景天（Sedum alfredii）中鉴定并功能表征了一个隶属于Hsf A4亚家族的转录本，将其命名为SaHsfA4c。该转录本的开放阅读框长度为1302 bp，编码一个由433个氨基酸组成的推定蛋白，且包含完整的DNA结合结构域（DNA-binding domain, DBD）。将SaHsfA4c在酵母中进行异源表达，可提升转基因酵母对镉胁迫的耐受性及镉积累量；而携带内含子、含有不完整DNA结合结构域的可变剪接转录本InSaHsfA4c，其表达则会使转基因酵母的镉胁迫耐受性较弱、镉积累量较低。本研究还在转基因拟南芥与非超富集生态型东南景天中，表征了SaHsfA4c在镉胁迫下的生物学功能。SaHsfA4c能够恢复拟南芥athsfa4c突变体的镉敏感表型。在转基因株系中，SaHsfA4c可降低活性氧（reactive oxygen species, ROS）的积累，并上调活性氧清除酶基因与热激蛋白（heat shock proteins, Hsps）的表达水平。本研究结果表明，SaHsfA4c可通过上调活性氧清除酶活性及热激蛋白的表达，增强植物对胁迫的抗性。