WUSCHEL/TILLERS ABSENT1—A key regulator of plant development

Plant development depends on the activity of meristems, such as the shoot apical meristem and flower meristem. These meristems contain pluripotent stem cells that proliferate for self-renewal or for cell supply for the differentiation of lateral organs including leaves and floral organs. The regulation of the balance between self-renewal and the supply of cells for differentiation is referred to as stem cell homeostasis, which is essential for sustainable plant development. Extensive studies in the model eudicot Arabidopsis (Arabidopsis thaliana) have demonstrated that WUSCHEL (WUS), a gene encoding a WOX transcription factor, plays a central role in maintaining stem cell homeostasis. Several studies in the model monocot rice (Oryza sativa) over the past decade have revealed the function of the WUS ortholog, TILLERS ABSENT1 (TAB1), whose developmental role is somewhat different from that of WUS. This review describes the roles of WUS/TAB1 in stem cell maintenance, highlighting both conserved and species-specific functions, as well as their additional roles in reproductive organogenesis.