Branch is an important lateral organ, which affects plant architecture and plant yield. Although some regulatory factors affecting the formation of lateral branches have been reported, the mechanism of the formation of lateral branches is still largely unknown. The number of branches and the size of organs are always coordinated in plants, and the mechanism of the action remains to be studied.
A research team led by Prof. LI Yunhai from the Institute of Genetics and Development Biology of the Chinese Academy of Sciences discovered a new mechanism by which the organ size regulator DA1 is involved in the formation of lateral branches.
Previous studies have shown that the ubiquitin-dependent peptidase DA1 and the ubiquitin specific protease UBP15 participate in seed- and organ- size regulation in Arabidopsis thaliana. Ubiquitinated DA1 cleaves UBP15 to promote the degradation of UBP15. In this study, the researchers found that DA1 and UBP15 are involved in the formation of lateral branches.
They found that the da1-1 single mutant forms fewer lateral branches due to defects in the initiation of axillary meristems. DA1 acts as a positive regulator in the formation of lateral branches.
They demonstrated that the transcription factors CUC2 and CUC3, which regulate the axillary meristem initiation, directly bind to the DA1 promoter and activate its expression. Genetic analyses suggest that DA1 functions with CUC2 and CUC3 in a common pathway to regulate the initiation of axillary meristems.
They found that overexpression of UBP15 causes the reduced number of lateral branches. Genetic analysis showed that CUC2/3, DA1 and UBP15 are involved in the same genetic pathway to regulate lateral branch formation.
This study builds up a novel genetic and molecular framework for CUC2/3-DA1-UBP15 regulatory module-mediated control of lateral branch formation.
The work was supported by National Natural Science Foundation of China and the strategic priority program of the Chinse Academy of Sciences.
CUC2/CUC3-DA1-UBP15 regulatory module-mediated control of axillary meristem initiation. (Image by IGDB)
