Fig. 6
OsMPKK6 promoted OsMPK4-OsVQ14/OsVQ32 cascade phosphorylation in the rice response to Xoo. The asterisks “**” indicate a significant difference between transgenic plants and WT plants at P < 0.01. a Interaction of OsMPK4 with OsMPKK6 in yeast. The interactions were assessed by growing yeast cells on synthetic defined premixes (SD) medium lacking (−) leucine (L), tryptophan (W), histidine (H), and adenine (A). AD, activation domain; BD, DNA-binding domain. Co-transformation of BD-53 and AD-RecT was used as the positive control while co-transformation of BD-Lam and AD-RecT was used as the negative control. b Interaction of OsMPK4 with OsMPKK6 in rice plants was analyzed by co-immunoprecipitation assay. Total protein was extracted from rice leaves and anti-OsMPK4 antibody was used for the immunoprecipitation (IP). c Phosphorylation assays of OsMPK4K72R by OsMPKK6 in vitro. Auto., Autoradiograph; CBB, Coomassie brilliant blue staining. d Analysis of the response of OsMPKK6 transgenic plants to Xoo infection. Bars represent mean (5 plants, with each plant having 3 to 5 leaves for lesion area) ± SD. e Analysis of the Xoo growth in rice leaves. Bars represent mean (3 leaves from 3 positive plants) ± SD. The significant difference was detected between transgenic plants and WT with the same treatment. cfu, colony-forming unit. f Analyses of the phosphorylation of OsMPK4, OsVQ14 and OsVQ32 in rice plants before and after Xoo infection. 0 h, immediately before Xoo inoculation. IP, immunoprecipitated. g Analyses of the expression of salicylic acid (SA)-signaling genes before (0 h) and after (4 h) Xoo infection. Bars represent the mean (three replicates) ± SD