Characterization of an inducible C2 H2 -type zinc finger transcription factor VuSTOP1 in rice bean (Vigna umbellata) reveals differential regulation between low pH and aluminum tolerance mechanisms

• Published in: The New phytologist 2015-10, Vol.208 (2), p.456
• Main Authors: Fan, Wei, Lou, He Qiang, Gong, Yu Long, Liu, Mei Ya, Cao, Meng Jie, Liu, Yu, Yang, Jian Li, Zheng, Shao Jian
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological - drug effects; Aluminum - toxicity; Amino Acid Sequence; Arabidopsis - physiology; Base Sequence; Cloning, Molecular; Cycloheximide - pharmacology; Fabaceae - drug effects; Fabaceae - genetics; Fabaceae - growth & development; Fabaceae - physiology; Gene Expression Regulation, Plant; Genetic Complementation Test; Glucuronidase - metabolism; Hydrogen-Ion Concentration; Models, Biological; Mutation - genetics; Plant Proteins - chemistry; Plant Proteins - genetics; Plant Proteins - metabolism; Plants, Genetically Modified; Protons; Real-Time Polymerase Chain Reaction; RNA, Messenger - genetics; RNA, Messenger - metabolism; Sequence Alignment; Subcellular Fractions - metabolism; Transcription Factors - chemistry; Transcription Factors - genetics; Transcription Factors - metabolism; Transcriptional Activation; Two-Hybrid System Techniques; Zinc Fingers
• ISSN: 1469-8137
• DOI: 10.1111/nph.13456

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.