D14-SCFD3-dependent degradation of D53 regulates strigolactone signalling
Feng Zhou,Qibing Lin,Lihong Zhu,Yulong Ren,Kunneng Zhou,Nitzan Shabek,Fuqing Wu,Haibin Mao,Wei Dong,Lu Gan,Weiwei Ma,He Gao,Jun Chen,Chao Yang,Dan Wang,Junjie Tan,Xin Zhang,Xiuping Guo,Jiulin Wang,Ling Jiang,Xi Liu,Weiqi Chen,Jinfang Chu,Cunyu Yan,Kotomi Ueno,Shinsaku Ito,Tadao Asami,Zhijun Cheng,Jie Wang,Cailin Lei,Huqu Zhai,Chuanyin Wu,Haiyang Wang,Ning Zheng & Jianmin Wan
National Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China
Abstract: Strigolactones (SLs), a newly discovered class of carotenoid-derived phytohormones, are essential for developmental processes that shape plant architecture and interactions with parasitic weeds and symbiotic arbuscular mycorrhizal fungi. Despite the rapid progress in elucidating the SL biosynthetic pathway, the perception and signalling mechanisms of SL remain poorly understood. Here we show that DWARF 53 (D53) acts as a repressor of SL signalling and that SLs induce its degradation. We find that the rice (Oryza sativa) d53 mutant, which produces an exaggerated number of tillers compared to wild-type plants, is caused by a gain-of-function mutation and is insensitive to exogenous SL treatment. The D53 gene product shares predicted features with the class I Clp ATPase proteins and can form a complex with the α/β hydrolase protein DWARF 14 (D14) and the F-box protein DWARF 3 (D3), two previously identified signalling components potentially responsible for SL perception. We demonstrate that, in a D14- and D3-dependent manner, SLs induce D53 degradation by the proteasome and abrogate its activity in promoting axillary bud outgrowth. Our combined genetic and biochemical data reveal that D53 acts as a repressor of the SL signalling pathway, whose hormone-induced degradation represents a key molecular link between SL perception and responses.