Figure 6.

RBG1 overexpression confers auxin hypersensitivity in cultured cells and promotes root development without exogenously applied auxin. (a) Suspension cells of WT, RBG1_Act and RBG1‐Ox lines were cultured in MS medium containing 2 mg/L (9 µm) and 0.04 mg/L (0.18 µm) of 2,4‐D. Cell volumes in 50 mL suspension cultures were measured after 14 days. Error bars indicate means ± SE for three independent repeats. (b) Morphology of suspension cells cultured in medium with (+) or without (−) 2,4‐D. (c) The root‐like structures regenerated from the RBG1_Act line grown in medium without 2,4‐D were sectioned and compared with the roots of WT regenerated in medium containing auxin (NAA at 2.69 µm). Scale bar = 50 μm. (d) Overexpression of RBG1 up‐regulates a large numbers of genes involved in auxin biosynthesis and signalling. Total RNA was extracted from shoots of plants at 35 DAI and subjected to RT‐PCR analysis. Red and blue fonts indicate up‐ and down‐regulation, respectively.