Figure 5.

ABA, PAMPs, and nonhost bacterial pathogens induce stomatal closure in NOG1-2-dependent manner. (A,B) The nog1-2 line impairs ABA-, PAMPs- and nonhost-bacterial-pathogen-induced stomatal closure. To observe stomatal behavior, epidermal peels of Col-0, nog1-2, NOG1-1-RNAi2, and NOG1-2 complemented lines were treated with stomata-opening buffer (KCl-MES), ABA (10 µM or 50 µM), flg22 (20 µM), Pstab and Psm at 1 × 10⁴ CFU/ml. Microscopic images were taken 3 hr after inoculation. The aperture size of stomata was measured after 30 min for ABA, 1 hr for flg22 and LPS, and 3 hr for Pstab and Psm. Asterisks indicate significant difference by Student’s t-test (P < 0.05). Error bars indicate standard error for counting 50 stomata/each epidermal peel. Three samples were examined for each treatment, and the experiment was repeated at least three times with similar results. (C) Bacterial entry through stomata in nog1-2 and NOG1-1-RNAi2 lines. To quantify bacterial entry, detached Arabidopsis leaves from wild-type Col-0 and nog1-2 and NOG1-1-RNAi2 were floated in bacterial suspensions (1 × 10⁴ CFU/ml) of the nonhost pathogen (Pstab) or host pathogen (Psm). After 1 hpi and 3 hpi, leaves were surface-sterilized with 10% bleach, ground, serially diluted and plated on KB media (B). After 2 days, the number of bacterial colony was counted. This experiment was repeated three times and showed similar results: five replications in each experiment. Asterisks indicate significant difference by Student’s t-test (P < 0.05).