Role of an ABA receptor SlPYL9 in tomato fruit ripening

Abstract
Abscisic acid (ABA) regulates fruit ripening, yet little is known about the exact roles of ABA receptors in fruit. In this study, we revealed the role of SlPYL9, a tomato PYR (pyrabactin resistance) / PYL (pyrobactin resistance-like) / RCAR (regulatory component of ABA receptors) ABA receptor, as a positive regulator of ABA signaling and fruit ripening. SlPYL9 inhibited protein phosphatase-type 2C (PP2C2/6) in ABA dose-dependent way, and it interacts physically with SlPP2C 2 / 3 / 4 / 5 in an ABA-dependent manner. Expression of SlPYL9 was observed in the seeds, flowers and fruit. Overexpression and suppression of SlPYL9 induced a variety of phenotypes via altered expression of ABA signaling genes (SlPP2C1/2/9, SlSnRK2.8, SlABF2), thereby affecting expression of ripening-related genes involved in ethylene release and cell wall modification. SlPYL9-OE / RNAi plants showed a typical ABA hyper- / hypo-sensitive phenotype in terms of seed germination, primary root growth and the re...