In plants and animals, self-renewing stem cell populations play fundamental roles in many developmental contexts. Plants differ from most animals in their retained ability to initiate new cycles of growth and development, which relies on the establishment and activity of branch meristems. In seed plants, branching is achieved by stem-cell-containing axillary meristems, which are initiated from a leaf axil meristematic cell population originally detached from the shoot apical meristem. It remains unclear how the meristematic cell fate is maintained.
Research team led by Prof. JIAO Yuling at Institute of Genetics and Developmental Biology of Chinese Academy of Sciences identifies ARABIDOPSIS THALIANA HOMEOBOX GENE1 (ATH1), a BEL1-like homeodomain (BLH) type three-amino-acid loop extension (TALE) class homeodomain protein, as a novel regulator for STM maintenance. ATH1 interacts with STM to activate STM transcription, establishing a self-activation loop that maintains stem cells to enable branching. Results show that ARABIDOPSIS THALIANA HOMEOBOX GENE1 (ATH1) maintains the meristem marker gene SHOOT MERISTEMLESS (STM) expression in the leaf axil to enable meristematic cell fate maintenance. Furthermore, ATH1 protein interacts with STM protein to form a STM self-activation loop. Genetic and biochemical data suggest that ATH1 anchors STM to activate STM as well as other axillary meristem regulatory genes. This auto-regulation allows the STM locus to remain epigenetically active. The study provides a striking example of a self-activation loop that maintains the flexibility required for stem cell niche re-establishment during organogenesis.
The research is published in Current Biology on April 2. Dr. CAO Xiuwei at University of Chinese Academy of Sciences (Institute: Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, supervisor: JIAO Yuling) is the first author, Prof. JIAO Yuling is the coreesponding author.
