Regulation of Maize Shoot Apical Meristem Structure and Function

The shoot apical meristem (SAM) positioned at the plant’s growing shoot tip harbours a population of pluripotent stem cells. These serve as a persistent source of cells for postembryonic growth and organogenesis. Whereas the roles for meristem regulators such as WUSCHEL (WUS) and CLAVATA3 (CLV3) are conserved across eudicots, substantial diversification in this and other regulatory modules between monocot and eudicot lineages exists. In particular, preliminary data shows that WUS-related transcription factors are expressed in the epidermis rather than the internal organizing center (OC) of the maize SAM. This project seeks to arrive at factors that provide, control, or interpret positional information needed to balance stem cell proliferation and organogenesis, and to maintain spatial organization within the maize SAM. To this end, we will: (i) test whether stem cell homeostasis is regulated by a WUS-CLV module that has diverged and been spatially displaced, (ii) discern the contribution of the epidermis and OC as signaling centers, and (iii) take advantage of the high levels of allelic polymorphism in maize to identify genes and genetic pathways underlying SAM architecture.