Postdoc The university of Tennessee Knoxville, Tennessee
Body of Abstract: The shoot apical meristem (SAM) is the site of leaf, internode, and flower initiation, and it determines the overall plant morphology. A signaling pathway consisting of ERECTA family (ERf) receptors and EPIDERMAL PATTERNING FACTOR LIKE (EPFL) ligands restricts SAM growth, promotes leaf initiation, and regulates phyllotaxy. ERf receptors regulate the meristem by controlling a negative feedback loop consisting of the transcription factor WUSCHEL (WUS) and a signaling pathway activated by the extracellular ligand CLAVATA3 (CLV3). Our work in Arabidopsis showed that ERf signaling inhibits the expression of WUS and CLV3 in the periphery of the SAM, confining them to the center and thus helping to define the stem cell area. Recently we used RNAseq to uncover new targets of ERfs in the meristem, used genetic analysis to investigate the contribution of different EPFLs to the regulation of WUS and CLV3 expression, and tested the new role of CLV3 in the regulation of WUS expression in the vegetative SAM using fluorescent markers. To understand the role of ERfs in leaf initiation and phyllotaxy, we used genetic and pharmacological approaches. Our study indicated that auxin cannot efficiently promote leaf and cotyledon initiation in the absence of ERfs suggesting that the SAM needs multiple signals to initiate organs. These findings advance our understanding of the mechanisms that promote aboveground morphogenesis.