Abstract
A PP2C homolog gene was cloned from the drought-treated cDNA library of Populus euphratica. Multiple sequence alignment analysis suggested that the gene is a potential ortholog of HAB1. The expression of this HAB1 ortholog (PeHAB1) was markedly induced by drought and moderately induced by ABA. To characterize its function in ABA signaling, we generated transgenic Arabidopsis thaliana plants overexpressing this gene. Transgenic lines exhibited reduced responses to exogenous ABA and reduced tolerance to drought compared to wide-type lines. Yeast two-hybrid analyses indicated that PeHAB1 could interact with the ABA receptor PYL4 in an ABA-independent manner. Taken together; these results indicated that PeHAB1 is a new negative regulator of ABA responses in poplar.
Highlights
The phytohormone abscisic acid (ABA) plays a key role in different plant developmental processes as well as in the perception of abiotic stresses such as drought, salt and cold [1,2]
Full-length PeHAB1 was isolated from cDNAs of roots, leaves and stems, indicating that PeHAB1 could be expressed in all these organs
Notable progress has been recently made in ABA signaling by identifying the Arabidopsis PYR/ PYL/RCAR gene family as ABA receptors that inhibit group-A PP2C activity in response to ABA
Summary
The phytohormone abscisic acid (ABA) plays a key role in different plant developmental processes as well as in the perception of abiotic stresses such as drought, salt and cold [1,2]. Water stress can lead to an increase of ABA level in plants, resulting in various adaptive responses, including stomatal closure and gene expression [3,4]. The ABA signal transduction system involves a complex network of both positive and negative regulators. Experimental data alternatively support that PP2C-like gene could act as a positive regulator rather than a negative regulator of ABA signaling [9], which indicated that PP2C play complicated roles in plants. ABA-related Clade A PP2Cs triggered the regulation of numerous processes by interaction with multiple proteins. Crystal graphic studies revealed the complex structure of PP2C-ABA-PYR1/PYL/RCAR (Pyrabactin Resistance 1 /PYR1-Like /Regulatory component of ABA receptor), among which PYL was identified as an intracellular
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