Protease Inhibitor-Dependent Inhibition of Light-Induced Stomatal Opening

• Published in: Frontiers in plant science Vol. 12; p. 735328
• Main Authors: Wang, Tenghua, Ye, Wenxiu, Wang, Yin, Zhang, Maoxing, Aihara, Yusuke, Kinoshita, Toshinori
• Format: Journal Article
• Language: English
• Published: Frontiers Media S.A 10.09.2021
• Subjects: Arabidopsis; chemical biology; Commelina; Plant Science; protease inhibitor; stomata
• ISSN: 1664-462X; 1664-462X
• DOI: 10.3389/fpls.2021.735328

Stomata in the epidermis of plants play essential roles in the regulation of photosynthesis and transpiration. Stomata open in response to blue light (BL) by phosphorylation-dependent activation of the plasma membrane (PM) H + -ATPase in guard cells. Under water stress, the plant hormone abscisic acid (ABA) promotes stomatal closure via the ABA-signaling pathway to reduce water loss. We established a chemical screening method to identify compounds that affect stomatal movements in Commelina benghalensis . We performed chemical screening using a protease inhibitor (PI) library of 130 inhibitors to identify inhibitors of stomatal movement. We discovered 17 PIs that inhibited light-induced stomatal opening by more than 50%. Further analysis of the top three inhibitors (PI1, PI2, and PI3; inhibitors of ubiquitin-specific protease 1, membrane type-1 matrix metalloproteinase, and matrix metalloproteinase-2, respectively) revealed that these inhibitors suppressed BL-induced phosphorylation of the PM H + -ATPase but had no effect on the activity of phototropins or ABA-dependent responses. The results suggest that these PIs suppress BL-induced stomatal opening at least in part by inhibiting PM H + -ATPase activity but not the ABA-signaling pathway. The targets of PI1, PI2, and PI3 were predicted by bioinformatics analyses, which provided insight into factors involved in BL-induced stomatal opening.