摘要
Proanthocyanidins(PAs)are the second most abundant plant phenolic natural products.PA biosynthesis is regulated by the well-documented MYB/bHLH/WD40(MBW)complex,but how this complex itself is regu-lated remains ill dened.Here,in situ hybridization and b-glucuronidase staining show that APETALA2(AP2),a well-dened regulator offlower and seed development,is strongly expressed in the seed coat endothelium,where PAs accumulate.AP2 negatively regulates PA content and expression levels of key PA pathway genes.AP2 activates MYBL2 transcription and interacts with MYBL2,a key suppressor of the PA pathway.AP2 exerts its function by directly binding to the AT-rich motifs near the promoter region of MYBL2.Molecular and biochemical analyses revealed that AP2 forms AP2–MYBL2–TT8/EGL3 com-plexes,disrupting the MBW complex and thereby repressing expression of ANR,TT12,TT19,and AHA10.Genetic analyses revealed that AP2 functions upstream of MYBL2,TT2,and TT8 in PA regulation.Our work reveals a new role of AP2 as a key regulator of PA biosynthesis in Arabidopsis.Overall,this study sheds new light on the comprehensive regulation network of PA biosynthesis as well as the dual regulatory roles of AP2 in seed development and accumulation of major secondary metabolites in Arabidopsis.
基金
supported by grants from the National Natural Science Foundation of China (31870281 to W.J.)
the Agricultural Science and Technology Innovation Program (ASTIP-IAS10).
