School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Republic of Korea.
FEBS Lett. 2013 Jun 19;587(12):1773-8. doi: 10.1016/j.febslet.2013.04.028. Epub 2013 May 6.
We have characterized the function of a plant R2R3-MYB transcription factor, Arabidopsis thaliana MYB20 (AtMYB20). Transgenic plants overexpressing AtMYB20 (AtMYB20-OX) enhanced salt stress tolerance while repression lines (AtMYB20-SRDX) were more vulnerable to NaCl than wild-type plants. Following NaCl treatment, the expressions of ABI1, ABI2 and AtPP2CA, which encode type 2C serine/threonine protein phosphatases (PP2Cs) that act as negative regulators in abscisic acid (ABA) signaling, were suppressed in AtMYB20-OX but induced in AtMYB20-SRDX. The electrophoretic mobility shift assay results revealed that AtMYB20 binds to the promoter regions containing the MYB recognition sequence (TAACTG) and an ACGT core element of ABI1 and AtPP2CA. These findings suggest that AtMYB20 down-regulates the expression of PP2Cs, the negative regulator of ABA signaling, and enhances salt tolerance.
我们对一种植物 R2R3-MYB 转录因子，拟南芥 MYB20（AtMYB20）的功能进行了研究。过表达 AtMYB20 的转基因植物（AtMYB20-OX）增强了耐盐性，而抑制表达系（AtMYB20-SRDX）比野生型植物对 NaCl 更敏感。在 NaCl 处理后，编码负调控脱落酸（ABA）信号的 2C 丝氨酸/苏氨酸蛋白磷酸酶（PP2C）的 ABI1、ABI2 和 AtPP2CA 的表达在 AtMYB20-OX 中受到抑制，但在 AtMYB20-SRDX 中诱导。电泳迁移率变动分析结果表明，AtMYB20 结合到包含 MYB 识别序列（TAACTG）和 ABI1 和 AtPP2CA 的 ACGT 核心元件的启动子区域。这些发现表明 AtMYB20 下调了 ABA 信号的负调节剂 PP2C 的表达，并增强了耐盐性。
