The transcription factor MYB40 is a central regulator in arsenic resistance in Arabidopsis

背景回顾：Arsenic is a metalloid that is toxic to plants. Arsenate (As(V)), the prevalent chemical form of arsenic, is a phosphate (Pi) analog and is incorporated into plant cells via Pi transporters. 

主要发现：Here, we found that the MYB40 transcription factor played important roles in the control of Arabidopsis As(V) resistance. 

结果1-MYB40表达模式：The expression of MYB40was induced by As(V) stress. 

结果2-MYB40过表达和突变表型：MYB40-overexpressing lines had an obvious As(V)-resistant phenotype and a reduced As(V)/Pi uptake rate, whereas myb40 mutants were sensitive to As(V) stress. 

结果3-MYB40-PHT1;1：Upon exposure to As(V), MYB40 directly repressed the expression of PHT1;1, which encodes a main Pi transporter. The As(V)-resistant phenotypes of MYB40-overexpressing lines were impaired by overexpression of PHT1;1, demonstrating an epistatic genetic relationship between MYB40 and PHT1;1. 

结果4-MYB40-PCS1和-ABCC1/2：Moreover, overexpression of MYB40 enhanced, and disruption of MYB40 reduced, thiol-peptide contents. Upon exposure to As(V), MYB40 positively regulated the expression of PCS1, which encodes a phytochelatin synthase, and ABCC1 and ABCC2, which encode the major vacuolar phytochelatin transporters. 

结论：Together, our data demonstrate that AtMYB40 acts as a central regulator of As(V) responses, providing a genetic strategy for enhancing plant As(V) tolerance and reducing As(V) uptake to improve food safety.

 摘 要 

砷是一种对植物有毒的类金属。砷的主要化学形式是砷酸盐As(V)，是一种磷酸盐（Pi）类似物，通过Pi转运蛋白被植物细胞吸入。本文中，作者发现MYB40转录因子在拟南芥As(V)抗性中发挥重要作用。MYB40基因的表达受到As(V)胁迫的诱导。MYB40过表达株系具有明显的As(V)抗性，植株对于As(V)/Pi的摄取率降低，而myb40突变株对As(V)胁迫较为敏感。在As(V)处理后，MYB40会直接抑制PHT1;1基因的表达，该基因编码一个主要的Pi转运体。在MYB40过表达株系中过表达PHT1;1基因，会导致原本高As(V)抗性表型减弱，说明MYB40与PHT1;1之间存在上位性遗传关系。此外，MYB40过表达增强了巯基肽的含量，而MYB40表达受损会降低巯基肽的含量。在As(V)处理后，MYB40会正向调控植物螯合肽合酶编码基因PCS1和主要液泡植物螯合肽转运蛋白编码基因ABCC1和ABCC2的表达。综上，本文的研究结果表明，AtMYB40作为As(V)响应的核心调控子，为提高植物的As(V)耐受性和减少As(V)吸收以改善食品安全提供了遗传策略。

 通讯作者 

** 陈益芳 **