Increased abscisic acid sensitivity and drought tolerance of Arabidopsis by overexpression of poplar abscisic acid receptors

Abscisic acid (ABA), a key plant hormone that regulates plant growth development and stress response, is recognized and bound by ABA Receptor PYR/PYL/RCAR (referred to as PYLs). However, little is known about the PYL gene family in Populus euphratica. Here, we identified 12 PYLs in P. euphratica, termed PePYL1-12. The phylogenetic analysis divided 12 PePYLs into three subfamilies according to structural features of the amino acid sequence. The Subcellular localization analysis found that PePYL1, PePYL2, PePYL3, PePYL4, PePYL5, PePYL6, PePYL7, PePYL8, PePYL9 PePYL10, PePYL11 and PePYL12 were located in the cytoplasm and nucleus. The promoter analysis showed that various hormones- and stress-related cis-acting elements in the promoter of 12 PePYLs. Additionally, the expression analysis of 12 PePYLs were detected under ABA and drought treatments. And PePYL6 and PePYL9 were significantly induced by ABA and drought treatments. Thus, we generated transgenic Arabidopsis plants overexpressing PePYL6 and PePYL9 to study the performance of PePYLs under drought stress. Transgenic plants exhibited increased ABA sensitivity during seed germination and root growth, improved water use efficiency and enhanced tolerance to drought compared to wide type plants. Taken together, our studies provide useful information for further investigating the role of other PePYLs in response to abiotic stress in poplar.