This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 20/1/75    most recent tpc.107.054544v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Jeon, B. W. Articles by Lee, Y. Search for Related Content PubMed PubMed Citation Articles by Jeon, B. W. Articles by Lee, Y. Agricola Articles by Jeon, B. W. Articles by Lee, Y.

The Arabidopsis Small G Protein ROP2 Is Activated by Light in Guard Cells and Inhibits Light-Induced Stomatal Opening^[W]

^a POSTECH-UZH Global Research Laboratories, Division of Molecular Life Sciences, POSTECH, Pohang 790-784, Korea
^b Center for Plant Cell Biology and Department of Botany and Plant Sciences, University of California, Riverside, California 92521-0124
^c Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742-5815

² Address correspondence to ylee{at}postech.ac.kr.

ROP small G proteins function as molecular switches in diverse signaling processes. Here, we investigated signals that activate ROP2 in guard cells. In guard cells of Vicia faba expressing Arabidopsis thaliana constitutively active (CA) ROP2 fused to red fluorescent protein (RFP-CA-ROP2), fluorescence localized exclusively at the plasma membrane, whereas a dominant negative version of RFP-ROP2 (DN-ROP2) localized in the cytoplasm. In guard cells expressing green fluorescent protein–ROP2, the relative fluorescence intensity at the plasma membrane increased upon illumination, suggesting that light activates ROP2. Unlike previously reported light-activated factors, light-activated ROP2 inhibits rather than accelerates light-induced stomatal opening; stomata bordered by guard cells transformed with CA-rop2 opened less than controls upon light irradiation. When introduced into guard cells together with CA-ROP2, At RhoGDI1, which encodes a guanine nucleotide dissociation inhibitor, inhibited plasma membrane localization of CA-ROP2 and abolished the inhibitory effect of CA-ROP2 on light-induced stomatal opening, supporting the negative effect of active ROP2 on stomatal opening. Mutant rop2 Arabidopsis guard cells showed phenotypes similar to those of transformed V. faba guard cells; CA-rop2 stomata opened more slowly and to a lesser extent, and DN-rop2 stomata opened faster than wild-type stomata in response to light. Moreover, in rop2 knockout plants, stomata opened faster and to a greater extent than wild-type stomata in response to light. Thus, ROP2 is a light-activated negative factor that attenuates the extent of light-induced changes in stomatal aperture. The inhibition of light-induced stomatal opening by light-activated ROP2 suggests the existence of feedback regulatory mechanisms through which stomatal apertures may be finely controlled.

This article has been cited by other articles:

				J. Seo, H. Y. Lee, H. Choi, Y. Choi, Y. Lee, Y.-W. Kim, S. B. Ryu, and Y. Lee Phospholipase A2{beta} mediates light-induced stomatal opening in Arabidopsis J. Exp. Bot., October 1, 2008; 59(13): 3587 - 3594. [Abstract] [Full Text] [PDF]