Plants differ from animals in their ability to establish new growth axis throughout the lifecycle. This is achieved throught the establishment of axillary meristems harbouring new stem cells in the leaf axil. It remains largely unknown how the new stem cells are activated.
A new research led by JIAO Yuling from the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences (CAS), showed that WUSCHEL (WUS), a homeodomain transcription factor involved in the maintanance of the shoot apical meristem, also regulated axillary meristem initiation.
Following their previous report on the requirement of a cytokinin pulse during axillary meristem initiation, the researchers further found that the transcription activator Type-B ARR of the cytokinin pathway could directly activate WUS expression to define new stem cell niches.
Furthermore, they found that cytokinin activation of WUS expression required a permisive epigenetic enviroment, which is under sptiotemporal regulation.
Taken together, their findings establish a mechanistic framework for the postembryonic establishment of the shoot stem cell niche, as shown in the figure below.
In addition, two other papers published in the Plant Cell
reported the same molecular mechanism was also utilized during adventitous shoot formation. The Jiao group contributed to one of the papers.
This study was supported by the the National Natural Science Foundation of China, the National Basic Research Program of China (973 Program), the National Program for Support of Top-Notch Young Professionals, and the State Key Laboratory of Plant Genomics.
A developmental framework of axillary meristem initiation (Image by IGDB)