Journal
PLANT CELL AND ENVIRONMENT
Volume 34, Issue 12, Pages 2172-2182Publisher
WILEY
DOI: 10.1111/j.1365-3040.2011.02413.x
Keywords
abscisic acid; CO2; drought; negative regulation; ROP GTPase; stomata
Categories
Funding
- Crop Functional Genomics Center of Korea [CG1-1-23]
- National Research Foundation of Korea
- Korean government [2010-0012958]
- World Class University (WCU) through the National Research Foundation of Korea
- Ministry of Education, Science and Technology [R31-2008-000-10105-0]
- National Research Foundation of Korea [2010-0012958] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
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ROP GTPases function as molecular switches in diverse cellular processes. Previously, we showed that ROP2 GTPase is activated upon light irradiation, and thereby negatively regulates light-induced stomatal opening. Here we studied the role of ROP2 during stomatal closure. The expression of a constitutively active form of ROP2 (CA-rop2) in Arabidopsis thaliana and Vicia faba resulted in slower and reduced stomatal closure in response to abscisic acid (ABA) and CO2. In contrast, the expression of a dominant-negative form of ROP2 (DN-rop2) and the knockout mutation of ROP2 (rop2 KO) promoted ABA-induced stomatal closure in Arabidopsis. As early as 10 min after ABA treatment, ROP2 was inactivated and translocated to the cytoplasm of the stomatal guard cells. To elucidate the mechanism by which active ROP2 suppresses stomatal closure, we monitored endocytotic membrane trafficking, which is regulated by Rho GTPases in animal cells. We found that the endocytosis of plasma membrane (PM), as tracked by FM4-64, was lower in CA-rop2-expressing guard cells than in those of wild-type plants, which suggests that active ROP2 suppresses the endocytotic internalization of PM, a process required for stomatal closure. Together, our results suggest that ROP2 is inactivated by ABA, and that this inactivation is required for the timely stomatal closure.
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