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First published online October 28, 2005; 10.1104/pp.105.068064 Plant Physiology 139:1350-1365 (2005) © 2005 American Society of Plant Biologists Transcriptome Analysis Reveals Specific Modulation of Abscisic Acid Signaling by ROP10 Small GTPase in Arabidopsis1,[w]Department of Biological Sciences, Lehman College, City University of New York, Bronx, New York 10468 (Z.X., Z.-L.Z.); Plant Sciences Ph.D. Subprogram, Graduate School and University Center, City University of New York, New York, New York 10016 (Z.-L.Z.); and Department of Biostatistics, Mailman School of Public Health, Columbia University, New York, New York 10016 (Y.Z.)
Abscisic acid (ABA) is a hormone that modulates a variety of agronomically important growth and developmental processes and various stresses responses, but its signal transduction pathways remain poorly understood. ROP10, a member of ROP small GTPases in Arabidopsis (Arabidopsis thaliana), is a plasma membrane-associated protein specifically involved in negative regulation of ABA responses. To dissect the ROP10-mediated ABA signaling, we carried out transcriptome analysis using the Arabidopsis full-genome chip. Our analysis revealed a total of 262 and 125 genes that were, respectively, up- and down-regulated (
1 This work was supported by the U.S. Department of Agriculture National Research Initiative Competitive Grants Program (grant no. 2004–35304–14911) and in part by the City University of New York (start-up fund to Z.-L.Z.). The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Zhi-Liang Zheng (zhiliang.zheng{at}lehman.cuny.edu). [w] The online version of this article contains Web-only data. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.105.068064. * Corresponding author; e-mail zhiliang.zheng{at}lehman.cuny.edu; fax 718–960–8236 Received July 6, 2005; returned for revision August 22, 2005; accepted September 1, 2005. This article has been cited by other articles:
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2-fold cutoff) by 1 µM ABA in wild type (Wassilewskija [Ws]); 42 up-regulated and 38 down-regulated genes have not been identified in other studies. Consistent with the nonpleiotropic phenotypes of rop10-1, only three genes were altered in rop10-1 in the absence of ABA treatment. In response to 1 µM ABA, 341 and 127 genes were, respectively, activated and repressed in rop10-1. Interestingly, a particular subset of 21 genes that were not altered by 1 µM ABA in Ws but only activated in rop10-1 was identified. Reverse transcription-polymerase chain reaction analysis revealed the existence of three distinct categories of ABA dose-response patterns. One novel category is characterized by their ABA unresponsiveness in Ws and activation in rop10-1 at 1 µM but not 10 and 100 µM of ABA. This indicates that ROP10 gates the expression of genes that are specific to low concentrations of ABA. Furthermore, almost all of these 21 genes are known to be highly induced by various biotic and abiotic stresses. Consequently, we found that rop10-1 enhanced the sensitivity of seed germination inhibition to mannitol and sodium chloride. Our results suggest that ROP10 negatively regulates ABA responses by specifically and differentially modulating the ABA sensitivity of a subset of genes including protein kinases and zinc-finger family proteins. 
