Fig. 8. MPK3/6-mediated VLN3 phosphorylation is required for MAMP-induced actin dynamicity in guard cells.

a Merged images from time-lapse series were shown in indicated genotypes following mock or 10 µM flg22 treatments for 10 min. Scale bar, 5 µm. b Correlation coefficient analyses were performed on time-lapse series from WT, vln3 mutant and complementary lines treated with mock or 10 µM flg22 for 10 min. Error bars represents SEM. Analyses were performed on time-lapse series taken from 10 leaves for each treatment and genotype. The sample sizes are indicated. Different letters indicate significant differences at P < 0.05, as determined by two-way ANOVA with Tukey’s multiple comparisons test. Black or red letters indicate data from mock or flg22 treatment, respectively. The exact p values are provided in the Source Data file. (c) A working model for the role of MPK3/6-VLN3 axis in regulating actin dynamics during stomatal immunity. Upon MAMP perception, VLN3 is phosphorylated by MPK3/6. This phosphorylation destabilizes the actin filaments, leading to radial actin array disruption in the open stomata, which facilitates actin reorganization to initiate MAMP-induced stomatal closure.