Figure 7
Constitutive cytokinin responses of 35S:ARR1D94 (PM- ox ) lines in anthocyanin accumulation, the timing of senescence and meristem size. (A) The anthocyanin content, expressed as absorbance value at 520 nm per 10 seedlings, was measured in six-day-old seedlings. The mean ± SD of three biological replicates is shown. Col-0 was treated with BA for 16 hours. One-way ANOVA with Tukey’s test was used to analyze the data. **, P < 0.01; ****, P < 0.0001. (B) Immunoblotting analyses of chalcone synthase (CHS) levels in eight-day-old seedlings. (C) Delayed senescence in PM-ox plants. Seedlings of the wild type, arr1-1, PM-ox, WT-ox and ipt-161 lines were grown on MS/2 media for 5 days, and then used to dissect cotyledons. Cotyledons were placed on moistened filter papers in petri dishes, and transferred to darkness. Photographs were taken at the indicated times. (D) Relative chlorophyll levels in cotyledons incubated in the dark for the indicated times. Chlorophyll content at day one for each line was assigned the value of 1. Mean ± SD of two independent samples (with 15 cotyledons each) is shown. (E) Analyses of the shoot apical meristem (SAM) size in six-day-old seedlings. SAM diameters measured from photomicrographs are presented as mean ± SEM (n = 25). Results were compared to Col-0 using a one-way ANOVA with Tukey’s test.*, P < 0.05; ***, P < 0.001. (F) Size of the root apical meristem (RAM) was analyzed in seven-day-old seedlings grown on vertically positioned plates. The number of RAM cortex cells measured from photomicrographs is presented as mean ± SEM (n = 25). Significance of the difference with Col-0 is shown. *, P < 0.05; **, P < 0.01 (one-way ANOVA with Tukey’s test).