Spatial and temporal regulation of At5g27930 and At3g16800 expression. Arabidopsis plants were germinated aseptically on MS medium with gellan gum. At 21 d after germination, seedlings were transferred to soil. (A, B) Expression of At5g27930 (A) and At3g16800 (B) transcripts. Total RNA from different tissues of wild-type Arabidopsis plants was isolated and subjected to RT-qPCR. The expression ratios of At5g27930 and At3g16800 to UBC9 were calculated for each sample. Values represent the mean ± SD of three independent experiments. Co, 7-d-old cotyledons; R14, 14-d-old roots; L14, 14-d-old first and second rosette leaves; R21, 21-d-old roots; L21, 21-d-old first to fourth rosette leaves; Fl, flowers; Si, siliques. (C–O) Histochemical analysis of GUS activity in Arabidopsis pAt5g27930:GUS (C–I) and pAt3g16800:GUS (J–O) transgenic plants. (C, J) A 21-d-old transgenic seedling. (D–F, K–M) A developmental series of rosette leaves ranging from young (D, K) to old (F, M) within a 21-d-old transgenic seedling. (G) Guard cells of young leaves. (H, N) Roots. (I, O) Flowers. Fi, filament; Pe, petal; Se, sepal; Sy, style. Scale bars: 10mm (C, J); 1mm (D–F, I, K–M, O); 500 μm (H, N); 50 μm (G).