油菜素甾醇
调节器
泛素连接酶
细胞生物学
生物
信号转导
RNA干扰
基因
F盒蛋白
下调和上调
泛素
生物化学
拟南芥
突变体
核糖核酸
作者
Xiaoxuan Sun,Yonghong Xie,Kai Xu,Jianxiong Li
摘要
F-box proteins participate in the regulation of many processes, including cell division, development, and plant hormone responses. Brassinosteroids (BRs) regulate plant growth and development by activating the core transcriptional and other multiple factors. OVATE family proteins (OFPs) of rice participate in BR signaling and regulate grain size. Here we identified FBX206 as an F-box E3 ubiquitin ligase that acts as a negative factor in BR signaling and regulates grain size and yield in rice. Suppressed expression of FBX206 by RNAi leads to promoted plant growth and increased grain yield. Molecular analyses showed that the expression levels of BR biosynthetic genes are upregulated whereas those of BR catabolic genes are downregulated in FBX206-RNAi plants, resulting in the accumulation of 28-homoBL, one of the bioactive BRs. FBX206 interacted with OsOFP8, a positive regulator in BR signaling, and OsOFP19, a negative regulator in BR signaling. SCFFBX206 mediated the degradation of OsOFP8 but suppressed OsOFP19 degradation. OsOFP8 interacted with OsOFP19, and the reciprocal regulation between OsOFP8 and OsOFP19 requires the presence of FBX206. FBX206 itself was ubiquitinated and degraded, but interactions of OsOFP8 and OsOFP19 synergistically suppressed the degradation of FBX206. Genetic interactions indicated the additive effect between FBX206 and OsOFP8 and the epistatic effects of OsOFP19 on FBX206 and OsOFP8. Our study reveals the regulatory networks of FBX206, OsOFP8, and OsOFP19 in BR signaling that regulate grain size and yield in rice.
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