Brachypodium distachyon BdPP2CA6 Interacts with BdPYLs and BdSnRK2 and Positively Regulates Salt Tolerance in Transgenic Arabidopsis.

Fan Zhang,Qiuhui Wei,Yang Zhang,Qingchen Luo,Yuesheng Wang,Junli Chang,Guangyuan He,Jiaochun Shi,Xia Jin,Yuan He,Guangxiao Yang

doi:10.3389/fpls.2017.00264

Fan Zhang, Qiuhui Wei + Show 9 more

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https://doi.org/10.3389/fpls.2017.00264

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Abstract

The phytohormone abscisic acid (ABA) is essential in plant responding to biotic and abiotic stresses. Although ABA signaling model is well established in Arabidopsis, ABA receptor PYL family and clade A PP2C subfamily are not yet characterized in monocot model plant Brachypodium distachyon. In this study, we identified 12 PYLs and 8 clade A PP2Cs from B. distachyon genome and successfully cloned 12 PYLs and 7 clade A PP2Cs. Bioinformatic and expression analyses showed that most of the identified genes respond to several signal molecules and abiotic stresses. Protein–protein interaction analysis revealed that many BdPYLs and BdPP2CAs participate in the classic ABA-PYL-PP2C-SnRK2 signaling pathway. A clade A PP2C, designated BdPP2CA6, interacted with BdPYL11 in the absence of ABA and localized in nucleus. Most clade A PP2C members from Arabidopsis showed negatively regulation in ABA signaling pathway, whereas BdPP2CA6-overexpression transgenic Arabidopsis showed ABA hypersensitive phenotype, resulting in enhanced stomatal closure and salinity tolerance. Our results indicate that BdPP2CA6 positively regulates ABA and stress signal pathway in transgenic Arabidopsis plant seedlings.

Highlights

Plants are constantly challenged by diverse biotic and abiotic stresses throughout their lifetime
Phylogenetic analyses were performed to construct phylogenetic trees by using full length amino acid sequences of BdPYL family or clade A BdPP2C subfamily, and the results showed that key domains of BdPYL proteins or clade A BdPP2C proteins are evolutionary conserved (Figure 1)
The results showed that six BdPYLs distributed on chromosome 2 and the rest members were localized on chromosomes 1 and 3, while six clade A BdPP2Cs distributed on chromosome 2 and the rest members were mapped on chromosomes 1 and 4 (Supplementary Figure S1)

Summary

Introduction

Plants are constantly challenged by diverse biotic and abiotic stresses throughout their lifetime. Complex stress-related signal transduction pathways have been evolved to cope with those biotic and abiotic stresses (Bohnert et al, 2006). Abscisic acid (ABA) is essential in plants responding to biotic and abiotic stresses and ABA signaling model is well established in model plant species Arabidopsis (Lee and Luan, 2012). Type 2C phosphatase (PP2C) is a kind of protein phosphatase that dephosphorylates Ser/Thr residues (Cohen, 1989). Clade A PP2C is a subgroup of PP2C family that inhibits ABA signaling in Arabidopsis (Lee and Luan, 2012). Core ABA signaling module is composed of three main components: PYR/PYL/RCAR

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