ABA-Dependent and ABA-Independent Functions of RCAR5/PYL11 in Response to Cold Stress.

has 14 abscisic acid (ABA) receptors-PYR1/PYLs/RCARs-which have diverse and redundant functions in ABA signaling; however, the precise role of these ABA receptors remains to be elucidated. Here, we report the functional characterization of RCAR5/PYL11 in response to cold stress. Expression of gene in dry seeds and leaves was ABA-dependent and ABA-independent, respectively. Under cold stress conditions, seed germination was negatively affected by the level of expression, which was dependent on ABA and was regulated by HAB1, OST1, and ABI5-downstream components of RCAR5 in ABA signaling. Leaves of -overexpressing plants showed enhanced stomatal closure-independent of ABA-and high expression levels of cold, dehydration, and/or ABA-responsive genes compared to those of wild-type; these traits conferred enhanced freezing tolerance. Our data suggest that RCAR5 functions in response to cold stress by delaying seed germination and inducing rapid stomatal closure ABA-dependent and ABA-independent pathways, respectively.