This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 19/6/1912    most recent tpc.106.048488v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via ISI Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Zhang, Y. Articles by Xie, Q. Search for Related Content PubMed PubMed Citation Articles by Zhang, Y. Articles by Xie, Q. Agricola Articles by Zhang, Y. Articles by Xie, Q.

SDIR1 Is a RING Finger E3 Ligase That Positively Regulates Stress-Responsive Abscisic Acid Signaling in Arabidopsis^[W]

^a State Key Laboratory of Plant Genomics, National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
^b State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-sen (Zhongshan) University, Guangzhou 510275, China
^c Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
^d State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100080, China

³ To whom correspondence should be addressed. E-mail qxie{at}genetics.ac.cn; fax 86-10-64889351.

Ubiquitination plays important roles in plant hormone signal transduction. We show that the RING finger E3 ligase, Arabidopsis thaliana SALT- AND DROUGHT-INDUCED RING FINGER1 (SDIR1), is involved in abscisic acid (ABA)-related stress signal transduction. SDIR1 is expressed in all tissues of Arabidopsis and is upregulated by drought and salt stress, but not by ABA. Plants expressing the ProSDIR1–ß-glucuronidase (GUS) reporter construct confirmed strong induction of GUS expression in stomatal guard cells and leaf mesophyll cells under drought stress. The green fluorescent protein–SDIR1 fusion protein is colocalized with intracellular membranes. We demonstrate that SDIR1 is an E3 ubiquitin ligase and that the RING finger conservation region is required for its activity. Overexpression of SDIR1 leads to ABA hypersensitivity and ABA-associated phenotypes, such as salt hypersensitivity in germination, enhanced ABA-induced stomatal closing, and enhanced drought tolerance. The expression levels of a number of key ABA and stress marker genes are altered both in SDIR1 overexpression and sdir1-1 mutant plants. Cross-complementation experiments showed that the ABA-INSENSITIVE5 (ABI5), ABRE BINDING FACTOR3 (ABF3), and ABF4 genes can rescue the ABA-insensitive phenotype of the sdir1-1 mutant, whereas SDIR1 could not rescue the abi5-1 mutant. This suggests that SDIR1 acts upstream of those basic leucine zipper family genes. Our results indicate that SDIR1 is a positive regulator of ABA signaling.

This article has been cited by other articles:

				J. Liu, Y. Zhang, G. Qin, T. Tsuge, N. Sakaguchi, G. Luo, K. Sun, D. Shi, S. Aki, N. Zheng, et al. Targeted Degradation of the Cyclin-Dependent Kinase Inhibitor ICK4/KRP6 by RING-Type E3 Ligases Is Essential for Mitotic Cell Cycle Progression during Arabidopsis Gametogenesis PLANT CELL, June 1, 2008; 20(6): 1538 - 1554. [Abstract] [Full Text] [PDF]