Fan Wei, Lou He Qiang, Gong Yu Long, Liu Mei Ya, Cao Meng Jie, Liu Yu, Yang Jian Li, Zheng Shao Jian
State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China.
College of Resources and Environment, Yunnan Agricultural University, Kunming, 650201, China.
New Phytol. 2015 Oct;208(2):456-68. doi: 10.1111/nph.13456. Epub 2015 May 13.
The rice bean (Vigna umbellata) root apex specifically secretes citrate through expression activation of Vigna umbellata Multidrug and Toxic Compound Extrusion 1 (VuMATE1) under aluminum (Al(3+) ) stress. However, the underlying mechanisms regulating VuMATE1 expression remain unknown. We isolated and characterized a gene encoding Sensitive to Proton Rhizotoxicity1 (STOP1)-like protein, VuSTOP1, from rice bean. The role of VuSTOP1 in regulating VuMATE1 expression was investigated using the yeast one-hybrid assay. We characterized the function of VuSTOP1 in Al(3) (+) - and H(+) -tolerance using in planta complementation assays. We demonstrated that VuSTOP1 has transactivation potential. We found that VuSTOP1 expression is inducible by Al(3+) and H(+) stress. However, although VuSTOP1 binds to the promoter of VuMATE1, the inconsistent tissue localization patterns of VuSTOP1 and VuMATE1 preclude VuSTOP1 as the major factor regulating VuMATE1 expression. In addition, when a protein translation inhibitor increased expression of VuSTOP1, VuMATE1 expression was inhibited. In planta complementation assay demonstrated that VuSTOP1 could fully restore expression of genes involved in H(+) tolerance, but could only partially restore expression of AtMATE. We conclude that VuSTOP1 plays a major role in H(+) tolerance, but only a minor role in Al(3+) tolerance. The differential transcriptional regulation of VuSTOP1 and VuMATE1 reveals a complex regulatory system controlling VuMATE1 expression.
在铝（Al(3+)）胁迫下，饭豆（Vigna umbellata）根尖通过激活饭豆多药和有毒化合物外排蛋白1（VuMATE1）的表达特异性地分泌柠檬酸。然而，调节VuMATE1表达的潜在机制仍不清楚。我们从饭豆中分离并鉴定了一个编码类质子根毒性敏感蛋白1（STOP1）的基因VuSTOP1。利用酵母单杂交试验研究了VuSTOP1在调节VuMATE1表达中的作用。我们通过植物体内互补试验表征了VuSTOP1在耐Al(3+)和耐H(+)方面的功能。我们证明VuSTOP1具有反式激活潜力。我们发现VuSTOP1的表达可被Al(3+)和H(+)胁迫诱导。然而，尽管VuSTOP1与VuMATE1的启动子结合，但VuSTOP1和VuMATE1不一致的组织定位模式排除了VuSTOP1作为调节VuMATE1表达的主要因子。此外，当蛋白质翻译抑制剂增加VuSTOP1的表达时，VuMATE1的表达受到抑制。植物体内互补试验表明，VuSTOP1可以完全恢复参与耐H(+)的基因的表达，但只能部分恢复AtMATE的表达。我们得出结论，VuSTOP1在耐H(+)中起主要作用，但在耐Al(3+)中仅起次要作用。VuSTOP1和VuMATE1的差异转录调控揭示了一个控制VuMATE1表达的复杂调控系统。
