[Control of organ shape and size by YUAN1 in Arabidopsis thaliana]

Control of organ shape and size by cell proliferationandcell expansion is a fundamental process in plant development. However, little is known about the molecular mechanisms that set the shape and size of determinate organs in plants. We have previously demonstrated that the Arabidopsis gene DA1 controls the final size of organs by restricting cell proliferation. Through an activation tagging screen for modifiers of da1-1, we have identified a semi-dominant mutant (yuan1-1D) with altered leaf shape and size. The yuan1-1D mutation results in reduced plant height, short and round leaves and short petioles due to defects in cell elongation. YUAN1 encodes a PHD zinc finger domain-containing protein. The GFP-YUAN1 fusion protein is localized to the nucleus. Overexpression of YUAN1 leads to round leaves and short petioles. Genetic analyses show that YUAN1 acts independently of DA1, ROTUNDIFOLIA 3 (ROT3) and ROTUNDIFOLIA4 (ROT4) to influence leaf shape and size. Collectively, our findings show that Arabidopsis YUAN1, a PHD zinc finger domain-containing protein, controls organ shape and size by restricting cell elongation, and give insight into how plants control their organ shape and size.