soluble ABA receptor PYL8 regulates drought resistance by controlling ABA signaling in Arabidopsis

The phytohormone abscisic acid (ABA) mediates plant responses to environmental stresses, including drought stress. Recent identification of a family of soluble ABA receptors has expanded our understanding of ABA signaling in plants. Here, we examined the function of PYL8, which encodes a soluble ABA receptor. Plants overexpressing PYL8 (PYL8ox) showed lower germination rates and more inhibition of root growth than wild-type plants in response to ABA; PYL8ox plants also showed enhanced drought tolerance. By contrast, PYL8-silenced (PYL8i) plants showed less inhibition of root growth in response to ABA; PYL8i plants also showed decreased drought tolerance, compared with wild-type plants. The PYL8ox plants showed higher transcript levels of ABA-responsive genes and PYL8i plants showed lower transcript levels of these genes. Altered expression of PYL8 did not affect expression of other PYL family members. We also found that subcellular localization of PYL8 changed in response to ABA. These results suggest that PYL8 plays an essential role in ABA-mediated developmental processes and drought responses.