A Ca2+/CaM-regulated transcriptional switch modulates stomatal development in response to water deficit

Chan Yul Yoo, Noel Mano, Aliza Finkler, Hua Weng, Irene S. Day, Anireddy S.N. Reddy, B. W. Poovaiah, Hillel Fromm, Paul M. Hasegawa, Michael V. Mickelbart*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Calcium (Ca2+) signals are decoded by the Ca2+-sensor protein calmodulin (CaM) and are transduced to Ca2+/CaM-binding transcription factors to directly regulate gene expression necessary for acclimation responses in plants. The molecular mechanisms of Ca2+/CaM signal transduction processes and their functional significance remains enigmatic. Here we report a novel Ca2+/CaM signal transduction mechanism that allosterically regulates DNA-binding activity of GT2-LIKE 1 (GTL1), a transrepressor of STOMATAL DENSITY AND DISTRIBUTION 1 (SDD1), to repress stomatal development in response to water stress. We demonstrated that Ca2+/CaM interaction with the 2nd helix of the GTL1 N-terminal trihelix DNA-binding domain (GTL1N) destabilizes a hydrophobic core of GTL1N and allosterically inhibits 3rd helix docking to the SDD1 promoter, leading to osmotic stress-induced Ca2+/CaM-dependent activation (de-repression) of SDD1 expression. This resulted in GTL1-dependent repression of stomatal development in response to water-deficit stress. Together, our results demonstrate that a Ca2+/CaM-regulated transcriptional switch on a trihelix transrepressor directly transduces osmotic stress to repress stomatal development to improve plant water-use efficiency as an acclimation response.

Original languageEnglish
Article number12282
JournalScientific Reports
Volume9
Issue number1
DOIs
StatePublished - 1 Dec 2019

Funding

FundersFunder number
Department of Energy Office of Science
Office of Biological and Environmental Research
National Science FoundationIOS-1021344, MCB-5333470
Division of Molecular and Cellular BiosciencesMCB-0424850
Division of Integrative Organismal Systems1021344
U.S. Department of Agriculture
National Institute of Food and AgricultureWINP00321, WNP00321, 2019-67013-29239
United States - Israel Binational Agricultural Research and Development FundIS-4749-14CR, IS-4243-09
Office of ScienceDE-SC0010733

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