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Proc Natl Acad Sci U S A. 2018 Nov 20;115(47):E11178-E11187. doi: 10.1073/pnas.1811491115. Epub 2018 Nov 5.

Arabidopsis thaliana NGATHA1 transcription factor induces ABA biosynthesis by activating NCED3 gene during dehydration stress.

Author information

1
Gene Discovery Research Group, RIKEN Center for Sustainable Resource Science, Tsukuba, 305-0074 Ibaraki, Japan; hikaru.sato@riken.jp kazuo.shinozaki@riken.jp.
2
Gene Discovery Research Group, RIKEN Center for Sustainable Resource Science, Tsukuba, 305-0074 Ibaraki, Japan.
3
College of Bioscience and Biotechnology, Chubu University, Kasugai, 487-8501 Aichi, Japan.
4
Experimental Plant Division, BioResource Research Center, RIKEN, Tsukuba, 305-0074 Ibaraki, Japan.
5
Plant Gene Regulation Research Group, Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, 305-8566 Ibaraki, Japan.
6
Graduate School of Science and Engineering, Saitama University, Saitama, 338-8570 Saitama, Japan.
7
Dormancy and Adaptation Research Unit, RIKEN Center for Sustainable Resource Science, Yokohama, 230-0045 Kanagawa, Japan.
8
Laboratory of Plant Molecular Physiology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 113-8657 Tokyo, Japan.

Abstract

The plant hormone abscisic acid (ABA) is accumulated after drought stress and plays critical roles in the responses to drought stress in plants, such as gene regulation, stomatal closure, seed maturation, and dormancy. Although previous reports revealed detailed molecular roles of ABA in stress responses, the factors that contribute to the drought-stress responses-in particular, regulation of ABA accumulation-remain unclear. The enzyme NINE-CIS-EPOXYCAROTENOID DIOXYGENASE 3 (NCED3) is essential for ABA biosynthesis during drought stress, and the NCED3 gene is highly induced by drought stress. In the present study, we isolated NGATHAs (NGAs) as candidate transcriptional regulators of NCED3 through a screen of a plant library harboring the transcription factors fused to a chimeric repressor domain, SRDX. The NGA proteins were directly bound to a cis-element NGA-binding element (NBE) in the 5' untranslated region (5' UTR) of the NCED3 promoter and were suggested to be transcriptional activators of NCED3 Among the single-knockout mutants of four NGA family genes, we found that the NGATHA1 (NGA1) knockout mutant was drought-stress-sensitive with a decreased expression level of NCED3 during dehydration stress. These results suggested that NGA1 essentially functions as a transcriptional activator of NCED3 among the NGA family proteins. Moreover, the NGA1 protein was degraded under nonstressed conditions, and dehydration stress enhanced the accumulation of NGA1 proteins, even in ABA-deficient mutant plants, indicating that there should be ABA-independent posttranslational regulations. These findings emphasize the regulatory mechanisms of ABA biosynthesis during early drought stress.

KEYWORDS:

ABA biosynthesis; NCED3; NGA; drought stress; transcriptional regulation

PMID:
30397148
PMCID:
PMC6255170
[Available on 2019-05-20]
DOI:
10.1073/pnas.1811491115
[Indexed for MEDLINE]

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