Uncovering the role of the FEI receptor-like kinases in cell wall function (2013)

Undergraduates: Stephanie Doctor, Blaire Steinwand

Faculty Advisor: Joseph Kieber
Department: Biology

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The plant cell wall is essential for mechanical support, defense against pathogens, and guiding cell expansion, and is the foundation of cellulosic biofuel. Cellulose microfibrils in the cell wall of a longitudinally expanding cell are deposited perpendicularly to the direction of expansion, constricting radial expansion. Despite the importance of the cell wall, the mechanisms that underlie the regulation of its function are poorly understood. In Arabidopsis, the FEI receptor-like kinases are required for cellulose synthesis. A fei1 fei2 double mutant is defective in cell expansion and displays a short, swollen root phenotype when plated under stress on high sucrose or salt. In order to better understand how the FEI pathway regulates cell wall function, we isolated shou4, a semi-dominant suppressor of fei1 fei2. We used map-based cloning to map shou4 to the bottom of chromosome 1, and whole genome sequencing to identify SHOU4 as the gene At1g78880. We furthermore characterized the shou4 suppressor mutation as a point mutation in the last base pair of the second intron of SHOU4 and determined that shou4 leads to a 45 bp, or 15 amino acid, in-frame deletion in the third exon, immediately following the point mutation. Future work will attempt to define the effect of this deletion on the protein in order to determine the role that SHOU4 plays in the FEI pathway, and ultimately to further elucidate the mechanism of cell wall regulation in Arabidopsis.