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

Abstract

The phytohormone abscisic acid (ABA) is essential in plant responding to biotic and abiotic stresses. Although ABA signaling model is well established in <i>Arabidopsis</i>, ABA receptor PYL family and clade A PP2C subfamily are not yet characterized in monocot model plant <i>Brachypodium distachyon</i>. In this study, we identified 12 <i>PYLs</i> and 8 clade A <i>PP2Cs</i> from <i>B. distachyon</i> genome and successfully cloned 12 <i>PYLs</i> and 7 clade A <i>PP2Cs</i>. 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 <i>Arabidopsis</i> showed negatively regulation in ABA signaling pathway, whereas <i>BdPP2CA6</i>-overexpression transgenic <i>Arabidopsis</i> showed ABA hypersensitive phenotype, resulting in enhanced stomatal closure and salinity tolerance. Our results indicate that <i>BdPP2CA6</i> positively regulates ABA and stress signal pathway in transgenic <i>Arabidopsis</i> plant seedlings.