WRKY72 Negatively Regulates Seed Germination Through Interfering Gibberellin Pathway in Rice

摘要

Seed germination is associated with grain yield and quality in crop production.Gibberellic acid(GA)serves as a major phytohormone in the promotion of seed germination.It is synthesized in the embryos and transmitted to the aleurone layers,where GA triggers the synthesis and secretion of a set of hydrolases,especiallyα-amylase.Subsequently,the storage nutrients such as starch in the endosperm are digested by these hydrolases and absorbed by the embryo to sustain seed germination and early seedling establishment(Kaneko et al,2002).The detailed GA biosynthesis process has been well studied and thoroughly reviewed in several literatures(Sakamoto et al,2004;Reinecke et al,2013).Briefly,geranylgeranyl diphosphate(GGDP)is turned into ent-kaurene by two terpene synthases,ent-copalyl diphosphate synthase(CPS)and ent-kaurene synthase(KS).Subsequently,the conversion of GA precursor ent-kaurene to ent-kaurenoic acid is catalyzed by ent-kaurene oxidase(KO),and that from ent-kaurenoic acid to GA12 is catalyzed by ent-kaurenoic acid oxidase(KAO).Ultimately,GA12 is converted to various GA intermediates and bioactive GAs by GA20-oxidase(GA20ox)and GA3-oxidase(GA3ox),respectively.