Release of GTP Exchange Factor Mediated Down-Regulation of Abscisic Acid Signal Transduction through ABA-Induced Rapid Degradation of RopGEFs
Fig 7
gef1/4/10 triple mutant plants are hypersensitive to ABA treatment.
(A) The percentage of seeds that germinated (radicle emergence) on 1/2 MS medium lacking (left) or supplemented with 0.5 μM ABA (right). Approximately 100 seeds of wild-type, gef1 T-DNA insertion single mutant and GFP-GEF1 overexpression transgenic lines were sown and scored for radical emergence for a time period of 6 d. (B) Quantification of ABA-mediated inhibition of primary root growth in wild type, gef1 T-DNA insertion single mutant and GFP-GEF1 overexpression transgenic lines. Thirty-two 4-day-old seedlings grown on 1/2 MS medium with similar primary root lengths were transferred onto 1/2 MS medium lacking or supplemented with 10 μM ABA. After 7 d of growth, images were taken and primary root length was measured with Image-J software. (C) Subcellular localization of the indicated RopGEFs in N. benthamiana leaves with or without ABA treatment. N. benthamiana leaves were treated with 50 μM ABA for 1 h before confocal imaging. Amplification factors for each panel were not identical and were set to visualize GFP fluorescence. Scale bars: 10 μm. (D) The germination percentage of wild-type and gef1/4/10 triple mutant seeds on 1/2 MS medium lacking (left) or supplemented with 0.5 μM ABA (right). (E) Photograph of seedlings grown on 1/2 MS media supplemented with or without 30 μM ABA taken 6 d after transferring seedlings. Scale bar: 1 cm. (F) gef1/4/10/14 quadruple mutant seeds showed enhanced sensitivity to ABA-mediated inhibition of seedling establishment. Images were taken 6 d (left) and 3 d (plus ABA, right) after stratification. Error bars represent standard deviation. A plate image of the same plate is shown in S11 Fig and includes gef1/4/10 and gef1/4/14 triple mutant seeds.