Format

Send to

Choose Destination
Plant Physiol. 2016 Oct;172(2):1182-1199. Epub 2016 Aug 4.

The Heat Stress Factor HSFA6b Connects ABA Signaling and ABA-Mediated Heat Responses.

Author information

1
Institute of Plant Biology and Department of Life Science, National Taiwan University, Taipei 10617, Taiwan.
2
Institute of Plant Biology and Department of Life Science, National Taiwan University, Taipei 10617, Taiwan jinnt@ntu.edu.tw.

Abstract

Heat stress response (HSR) is a conserved mechanism developed to increase the expression of heat shock proteins (HSPs) via a heat shock factor (HSF)-dependent mechanism. Signaling by the stress phytohormone abscisic acid (ABA) is involved in acquired thermotolerance as well. Analysis of Arabidopsis (Arabidopsis thaliana) microarray databases revealed that the expression of HSFA6b, a class A HSF, extensively increased with salinity, osmotic, and cold stresses, but not heat. Here, we show that HSFA6b plays a pivotal role in the response to ABA and in thermotolerance. Salt-inducible HSFA6b expression was down-regulated in ABA-insensitive and -deficient mutants; however, exogenous ABA application restored expression in ABA-deficient, but not -insensitive plants. Thus, ABA signaling is required for proper HSFA6b expression. A transcriptional activation assay of protoplasts revealed that ABA treatment and coexpression of an ABA signaling master effector, ABA-RESPONSIVE ELEMENT-BINDING PROTEIN1, could activate the HSFA6b promoter. In addition, HSFA6b directly bound to the promoter of DEHYDRATION-RESPONSIVE ELEMENT-BINDING PROTEIN2A and enhanced its expression. Analysis of ABA responses in seed germination, cotyledon greening, and root growth as well as salt and drought tolerance in HSFA6b-null, overexpression, and dominant negative mutants revealed that HSFA6b is a positive regulator participating in ABA-mediated salt and drought resistance. Thermoprotection tests showed that HSFA6b was required for thermotolerance acquisition. Our study reveals a network in which HSFA6b operates as a downstream regulator of the ABA-mediated stress response and is required for heat stress resistance. This new ABA-signaling pathway is integrated into the complex HSR network in planta.

PMID:
27493213
PMCID:
PMC5047099
DOI:
10.1104/pp.16.00860
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center