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Cuticular wax biosynthesis is positively regulated by WRINKLED 4, an AP 2/ ERF ‐type transcription factor, in Arabidopsis stems
Author(s) -
Park Chan Song,
Go Young Sam,
Suh Mi Chung
Publication year - 2016
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13248
Subject(s) - arabidopsis , silique , wax , abscisic acid , transactivation , transcription factor , biology , chromatin immunoprecipitation , botany , wild type , biochemistry , epicuticular wax , microbiology and biotechnology , mutant , gene expression , gene , promoter
Summary The aerial surfaces of terrestrial plants are covered by a cuticular wax layer, which protects the plants from environmental stresses such as desiccation, high irradiance, and UV radiation. Cuticular wax deposition is regulated in an organ‐specific manner; Arabidopsis stems have more than 10‐fold higher wax loads than leaves. In this study, we found that WRINKLED 4 ( WRI 4 ), encoding an AP 2/ ERF (ethylene‐responsive factor) transcription factor ( TF ), is predominantly expressed in stem epidermis, is upregulated by salt stress, and is involved in activating cuticular wax biosynthesis in Arabidopsis stems. WRI 4 harbors a transcriptional activation domain at its N‐terminus, and fluorescent signals from a WRI 4: eYFP construct were localized to the nuclei of tobacco leaf protoplasts. Deposition of epicuticular wax crystals on stems was reduced in wri4‐1 and wri4‐3 knockout mutants. Total wax loads were reduced by ~28% in wri4 stems but were not altered in wri4 siliques or leaves compared to the wild type. The levels of 29‐carbon long alkanes, ketones, and secondary alcohols, which are the most abundant components of stem waxes, were significantly reduced in wri4 stems relative to the wild type. A transactivation assay in tobacco protoplasts and a chromatin immunoprecipitation (Ch IP ) assay showed that the expression of long‐chain acyl‐CoA synthetase1 ( LACS 1 ), β–ketoacyl CoA reductase1 ( KCR 1 ), PASTICCINO 2 ( PAS 2 ), trans ‐2,3‐enoyl‐CoA reductase ( ECR ), and bifunctional wax synthase/acyl‐CoA: diacylglycerol acyltransferase ( WSD 1 ) is positively regulated by direct binding of WRI 4 to their promoters. Taken together, these results suggest that WRI 4 is a transcriptional activator that specifically controls cuticular wax biosynthesis in Arabidopsis stems.