The 30th International Conference on Arabidopsis Research (ICAR 2019)

386 / 2019-02-18 12:02:57

A self-activation loop maintains meristematic cell fate

Arabidopsis thaliana,axillary meristem,meristematic cell fate,STM,ATH1

Plenary track > Development

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 axillary meristems, which are initiated from a leaf axil stem cell population originally detached from the shoot apical meristem. It remains unclear how the stem cell fate is maintained. Here we show that the meristem marker gene SHOOT MERISTEMLESS (STM) can activate its own expression to enable cell fate maintenance. Furthermore, the self-activation loop requires an STM-interacting protein ARABIDOPSIS THALIANA HOMEOBOX GENE1 (ATH1). Genetic and biochemical data suggest that ATH1 anchors STM to activate STM as well as additional axillary meristem regulatory genes. This auto-regulatory loop maintains the STM locus epigenetically active. Taken together, our finding provides a striking example in which a self-activation loop maintains the flexibility to re-establish a stem cell niche during organogenesis.