Figure 5.

T-DNA insertion mutants of subfamilies 2 and 3 have minimal effect on cytokinin responses. A, Schematic of the T-DNA insertions in type-B ARR subfamily 2 and 3 genes, arr13-1, arr19-1, arr20-1, and arr21-2. Bar = 500 bp. B, RT-PCR showing lack of ARR19, ARR20, and ARR21 transcript levels in the siliques and flowers (as indicated) of arr19-1, arr20-1, and arr21-2 mutant lines. ARR13 (not shown) was undetectable in the wild type, even after 40 amplification cycles as previously reported (Mason et al., 2004). β-tubulin3 (At5g62700) was used as a loading control. C, Effect of subfamily 2 and 3 mutants on cytokinin sensitivity of the root. The root growth of seedlings grown on media containing 0.1 μm BA is expressed as a percentage of the growth of siblings grown on DMSO control media. Root growth was measured from day 4 through day 7. Error bars indicate se. D, Subfamily 2 and 3 mutations exhibit no additive effects on the cytokinin sensitivity of the root when combined with arr1-3. Lines were analyzed for significant differences in their responsiveness to cytokinin based on Tukey’s multiple range test among the means on the ANOVA (P < 0.05). Lines designated with the same letter exhibit no significant difference.