Figure 6.

NOG1-2 has GTPase activity and is functionally involved in JA- and ABA-mediated signaling pathway. (A) Left Panel: Rate of Pi release due to the GTPase activity of NOG1-2 protein (1 µM) in the presence of varying concentrations of GTP. Experiments were repeated three times, and data were averaged. Error bars represent the mean ± S.E. Right panel: The transgenic Arabidopsis or N. benthamiana plants expressing AtNOG1-2-GFP under native promoter of AtNOG1-2 or NbNOG1-GFP under 35 S promoter, respectively. Arrows represent nuclei in guard cells. One week of seedlings were observed for the localization of AtNOG1-2 under confocal laser microscopy. Scale bar is 10 µM. Atnog1-2 is less sensitive to JA than Col-0. (B) Atnog1-2 line, compared to wild-type Col-0, is less sensitive to JA. Seeds of different Arabidopsis lines were grown in ½ MS medium plates with or without 30 and 50 µM of MeJA, and 7 days later root lengths were measured. Three independent experiments were done, with at least 10 seedlings for each line. Bars represent means ± SD. Asterisks indicate significant difference from Col-0 by Student’s t-test (P < 0.05). (C) The mutation of AtNOG1-2 increases sensitivity to drought stress and ABA. Wild-type (Col-0) and nog1-2 plants were grown for four weeks (21 °C/14 hr day and 18 °C/10 hr night), then plants were dehydrated until drought symptom appeared. After leaves were completely collapsed, plants were re-watered to revive. nog1-2 seedlings are less sensitive to ABA. Seedlings of Col-0 and nog1-2 were grown in MS or MS with ABA (1uM) for 2-weeks.