Developmental and stimulus-induced expression patterns of Arabidopsis calmodulin-like genes CML37, CML38 and CML39
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Various aspects of plant development and stress physiology are mediated by Ca2+ signaling. Ca2+ sensors, such as calmodulin, detect these signals and direct downstream signaling pathways by binding and activating diverse targets. Plants possess many unique, putative Ca2+ sensors, including a large family (50 in Arabidopsis) of calmodulin-like proteins termed CMLs. Some of these CMLs have been implicated in Ca2+-based stress response but most remain unstudied. We generated transgenic plants expressing CML::GUS reporter genes for members of a subfamily of CMLs (CML37, CML38 and CML39) which allowed us to investigate their expression patterns in detail. We found that CML::GUS genes displayed unique tissue, cell-type, and temporal patterns of expression throughout normal development, particularly in the flower, and in response to a variety of stimuli, including biotic and abiotic stress, hormone and chemical treatments. Our findings are supported by semiquantitative reverse-transcription PCR as well as analyses of microarray databases. Analysis of purified, recombinant CMLs demonstrated their ability to bind Ca2+ in vitro. Collectively, our data suggest that these CMLs likely play important roles as sensors in Ca2+-mediated developmental and stress response pathways and provide a framework of spatial and temporal expression to direct future studies aimed at elucidating their physiological roles.
KeywordsCalcium Calmodulin Development GUS transgenics Stress
Murashige and Skoog
programmed cell death
reactive oxygen species
reverse transcription polymerase chain reaction
This work was supported by a research grant (WAS) and post-graduate scholarship (BV) from Natural Sciences and Engineering Research Council of Canada and a post-graduate scholarship (BV) from the Ontario Graduate Scholarship program. The authors thank Drs Sharon Regan and Brent Kaiser for a critical reading of the manuscript.
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