Yoo, Chan Yul , Jin, Jing Bo , Miura, Kenji , Jin, Yin Hua , Gosney, Michael , Mickelbart, Michael V. , Bressan, Ray A. , Hasegawa, Paul M. .
Ca2+/CaM signaling through AtGTL1 mediates drought stress adaptation.
Drought stress is a most critical limitation to plant growth and productivity. Plants have complex adaptation mechanisms that include sensing and signaling, and adaptation processes. Calcium (Ca2+) is a focal secondary messenger that is implicated in drought stress adaptation signaling of plants, and calmodulin (CaM) is presumed to be one of the primary Ca2+ signature-decoding molecules. Genome-wide screening of expression libraries using labeled recombinant CaM has revealed that AtGT2 (GT elements-binding proteins) family are potential CaM binding transcription factors. AtGTL1, one of the AtGT2 family, encodes a putative trihelix transcription factor that binds Ca2+/CaM. gtl1 T-DNA insertional mutations (gtl1-1, gtl1-2 and gtl1-3) substantially enhance the capacity of plants to survive in response to severe water deficit stress. Furthermore, gtl1 plants are equivalent in size to wild type under irrigation, but are able to sustain shoot growth under mild water deficits relative to wild type. AtGTL1 transcript abundance decreased with dehydration stress, which is consistent with the notion that the transcription factor is a negative regulator of drought adaptation response, which is important to maintain homeostasis for adaptation processes. Gene expression analysis by RT-PCR revealed that GTL1 regulates DREB2A expression in ABA-independent pathway, not ABA-dependent gene expression. We hypothesize that Ca2+/CaM-mediated GTL1 regulates drought stress adaptation through mechanism by which is linked to efficient carbon usage process. This research will provide functional understanding about how plants decode Ca2+/CaM signals to initiate stress adaptation processes that could enhance crop yield stability under water deficit conditions.
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1 - Purdue University, Center for Plant Environmental Stress Physiology
Presentation Type: ASPB Minisymposium
Location: Continental A/Hilton
Date: Sunday, July 8th, 2007
Time: 4:10 PM