Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 113, Issue 11, Pages 3090-3095Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1600399113
Keywords
cytokinin signaling; drought adaption; comparative transcriptome analysis; type B response regulators
Categories
Funding
- Core Research for Evolutional Science and Technology, Japan Science and Technology
- National Science Foundation [IOS-1022053]
- International Program Associate of RIKEN
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In this study, we used a loss-of-function approach to elucidate the functions of three Arabidopsis type B response regulators (ARRs)-namely ARR1, ARR10, and ARR12-in regulating the Arabidopsis plant responses to drought. The arr1,10,12 triple mutant showed a significant increase in drought tolerance versus WT plants, as indicated by its higher relative water content and survival rate on drying soil. This enhanced drought tolerance of arr1,10,12 plants can be attributed to enhanced cell membrane integrity, increased anthocyanin biosynthesis, abscisic acid (ABA) hypersensitivity, and reduced stomatal aperture, but not to altered stomatal density. Further drought-tolerance tests of lower-order double and single mutants indicated that ARR1, ARR10, and ARR12 negatively and redundantly control plant responses to drought, with ARR1 appearing to bear the most critical function among the three proteins. In agreement with these findings, a comparative genome-wide analysis of the leaves of arr1,10,12 and WT plants under both normal and dehydration conditions suggested a cytokinin (CK) signaling-mediated network controlling plant adaptation to drought via many dehydration/droughtand/or ABA-responsive genes that can provide osmotic adjustment and protection to cellular and membrane structures. Expression of all three ARR genes was repressed by dehydration and ABA treatments, inferring that plants down-regulate these genes as an adaptive-mechanism to survive drought. Collectively, our results demonstrate that repression of CK response, and thus CK signaling, is one of the strategies plants use to cope with water deficit, providing novel insight for the design of drought-tolerant plants by genetic engineering.
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