Lateral branches are important for plant architecture and production, but how plants determine their lateral branches remains to be further understood. Here, we report that the CUP-SHAPED COTYLEDON2 (CUC2)/CUC3-DA1-UBIQUITIN-SPECIFIC PROTEASE15 (UBP15) regulatory module controls the initiation of axillary meristems, thereby determining the number of lateral branches in Arabidopsis (Arabidopsis thaliana). Mutation in the ubiquitin-dependent peptidase DA1 causes fewer lateral branches due to defects in the initiation of axillary meristems. The transcription factors CUC2 and CUC3, which regulate the axillary meristem initiation, directly bind to the DA1 promoter and activate its expression. Further results show that UBP15, which is a direct substrate of DA1 peptidase, represses the initiation of axillary meristems. Genetic analyses support that CUC2/CUC3, DA1, and UBP15 function, at least in part, in a common pathway to regulate the initiation of axillary meristems. Therefore, our findings establish a genetic and molecular framework by which the CUC2/CUC3-DA1-UBP15 regulatory module controls the initiation of axillary meristems, thereby determining plant architecture.

横向分支对于植物的结构和生产很重要，但是植物如何确定其横向分支还有待进一步理解。在这里，我们报告说，杯状子叶2（CUC2）/ CUC3-DA1-UBIQUITIN-SPECIFIC PROTEASE15（UBP15）调控模块控制腋生分生组织的启动，从而确定拟南芥（Arabidopsis thaliana）中侧枝的数量。由于腋生分生组织的起始缺陷，泛素依赖性肽酶DA1中的突变导致较少的侧枝。调节腋生分生组织起始的转录因子CUC2和CUC3直接与DA1结合启动子并激活其表达。进一步的结果表明，作为DA1肽酶直接底物的UBP15抑制了腋生分生组织的启动。遗传分析支持CUC2 / CUC3，DA1和UBP15至少部分地在调节腋生分生组织起始的共同途径中起作用。因此，我们的发现建立了遗传和分子框架，CUC2 / CUC3-DA1-UBP15调节模块可通过该框架控制腋生分生组织的启动，从而确定植物的结构。