Figure 2.

Al and H⁺ tolerance of transgenic tobacco plants with NtSTOP1 suppressed by RNAi inhibition. A, Transgenic tobacco was obtained by A. tumefaciens-mediated transformation using a vector carrying an NtSTOP1 RNAi construct. A partial cDNA of NtSTOP1 sandwiched the first intron of NADP-dependent isocitrate dehydrogenase of Arabidopsis, and the gene construct was driven by the cauliflower mosaic virus 35S promoter (CaMV35s). B, Suppression of NtSTOP1 was analyzed in T3 seed progeny of three independent transgenic lines (NtSTOP1-KD1, NtSTOP1-KD2, and NtSTOP1-KD3) by RT-PCR using ACTIN as the internal control. C, Seedlings of T3 seed progeny of NtSTOP1-KD and the wild type (WT) were grown hydroponically for 1 week in Al-toxic solutions (pH 5.0, 2 and 4 μm) and different levels of H⁺ toxicity (pH 5.2, 5.0, and 4.7). Means and sd of relative values (percentage of the control; pH 5.0, 0 Al for Al, pH 5.5 for pH; absolute root lengths are shown in Supplemental Fig. S2) from five seedlings are shown.