Control of rice pre‐harvest sprouting by glutaredoxin‐mediated abscisic acid signaling

Summary Pre‐harvest sprouting ( PHS ) is one of the major problems in cereal production worldwide, which causes significant losses of both yield and quality; however, the molecular mechanism underlying PHS remains largely unknown. Here, we identified a dominant PHS mutant phs9‐D . The corresponding gene PHS 9 encodes a higher plant unique CC ‐type glutaredoxin and is specifically expressed in the embryo at the late embryogenesis stage, implying that PHS 9 plays some roles in the late stage of seed development. Yeast two‐hybrid screening showed that PHS 9 could interact with Os GAP , which is an interaction partner of the abscicic acid ( ABA) receptor Os RCAR 1. PHS 9 ‐ or Os GAP overexpression plants showed reduced ABA sensitivity in seed germination, whereas PHS 9 or Os GAP knock‐out mutant plants showed increased ABA sensitivity in seed germination, suggesting that PHS 9 and Os GAP acted as negative regulators in ABA signaling during seed germination. Interestingly, the germination of PHS 9 and Os GAP overexpression or knock‐out plant seeds was weakly promoted by H 2 O 2 , implying that PHS 9 and Os GAP could affect reactive oxygen species ( ROS ) signaling during seed germination. These results indicate that PHS 9 plays an important role in the regulation of rice PHS through the integration of ROS signaling and ABA signaling.