OSR2 increases the rate of cell expansion in developing leaves. (A, B) Relative cell expansion rate of the epidermal cells at the tip (A) and base (B) of the third leaves of control and pro35S:OSR2 transgenic plants (L1). At least five leaves from each genotype were examined. (C) Nuclear polyploidization analysis of the leaf cells in the control and L1 pro35S:OSR2 transgenic lines. Fully-expanded blades of the third leaves were used for cell nuclear ploidy analysis with a flow cytometer. The percentages of cells with different nuclear polyploidy levels were observed from three independent biological duplicates, and are shown as mean values ± SE.