Time-Series Transcriptomics Reveals That AGAMOUS-LIKE22 Affects Primary Metabolism and Developmental Processes in Drought-Stressed Arabidopsis
American Society of Plant Biologists
Open access. © 2016 American Society of Plant Biologists. All rights reserved.
In Arabidopsis thaliana, changes in metabolism and gene expression drive increased drought tolerance and initiate diverse drought avoidance and escape responses. To address regulatory processes that link these responses, we set out to identify genes that govern early responses to drought. To do this, a high-resolution time series transcriptomics data set was produced, coupled with detailed physiological and metabolic analyses of plants subjected to a slow transition from well-watered to drought conditions. A total of 1815 drought-responsive differentially expressed genes were identified. The early changes in gene expression coincided with a drop in carbon assimilation, and only in the late stages with an increase in foliar abscisic acid content. To identify gene regulatory networks (GRNs) mediating the transition between the early and late stages of drought, we used Bayesian network modeling of differentially expressed transcription factor (TF) genes. This approach identified AGAMOUS-LIKE22 (AGL22), as key hub gene in a TF GRN. It has previously been shown that AGL22 is involved in the transition from vegetative state to flowering but here we show that AGL22 expression influences steady state photosynthetic rates and lifetime water use. This suggests that AGL22 uniquely regulates a transcriptional network during drought stress, linking changes in primary metabolism and the initiation of stress responses.
The authors acknowledge the support of the UK Biotechnology and Biological Science Research Council (BBSRC; Grant BB/F005806/1). S.S. was supported by a University of Essex PhD studentship. J.S.A.M. is supported by an NERC-CASE award (ENV-EATR-DTP: NE/L002582/1), and S.R.M.V-C. is supported by the BBSRC (BB/1001187_1). R.F. and J.E.L. are supported by the Max Planck Society. N.S. and H.F. are supported by Exeter Science Strategy funding, and C.S. is supported by the BBSRC and the Department for Environment, Food, and Rural Affairs through the NORNEX project. D.L.S was supported by a Wellcome Trust Institutional Strategic Support Fund. We thank Susan Corbett and Phillip A. Davey for help with the drought experiments and gas exchange measurements.
This is the author accepted manuscript. The final version is available from the American Society of Plant Biologists via the DOI in this record.
Vol. 28 (2), pp. 345 - 366
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