Abstract
BackgroundIn light of the changes in precipitation and soil water availability expected with climate change, understanding the mechanisms underlying plant responses to water deficit is essential. Toward that end we have conducted an integrative analysis of responses to drought stress in the perennial C4 grass and biofuel crop, Panicum virgatum (switchgrass). Responses to soil drying and re-watering were measured at transcriptional, physiological, and metabolomic levels. To assess the interaction of soil moisture with diel light: dark cycles, we profiled gene expression in drought and control treatments under pre-dawn and mid-day conditions.ResultsSoil drying resulted in reduced leaf water potential, gas exchange, and chlorophyll fluorescence along with differential expression of a large fraction of the transcriptome (37%). Many transcripts responded differently depending on time of day (e.g. up-regulation pre-dawn and down-regulation mid-day). Genes associated with C4 photosynthesis were down-regulated during drought, while C4 metabolic intermediates accumulated. Rapid changes in gene expression were observed during recovery from drought, along with increased water use efficiency and chlorophyll fluorescence.ConclusionsOur findings demonstrate that drought responsive gene expression depends strongly on time of day and that gene expression is extensively modified during the first few hours of drought recovery. Analysis of covariation in gene expression, metabolite abundance, and physiology among plants revealed non-linear relationships that suggest critical thresholds in drought stress responses. Future studies may benefit from evaluating these thresholds among diverse accessions of switchgrass and other C4 grasses.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-527) contains supplementary material, which is available to authorized users.
Highlights
In light of the changes in precipitation and soil water availability expected with climate change, understanding the mechanisms underlying plant responses to water deficit is essential
Physiological effects of drought and recovery The reduced soil water content imposed by the drought treatment (Figure 1a) caused visible indications of stress by day 13, at which point ~50% of plants showed leaf yellowing and rolling, but not senescence
Consistent with previous studies of gene expression responses to drought, [19,25,29,58,59], we found that genes involved with photosynthetic light reactions (PSI) and carbon fixation (PSII) were down regulated in the drought treatment
Summary
In light of the changes in precipitation and soil water availability expected with climate change, understanding the mechanisms underlying plant responses to water deficit is essential. While reduced stomatal conductance may limit net photosynthesis (ACO2) during drought, intense water deficits can trigger down-regulation of the entire photosynthetic apparatus [10]. These changes limit wholeplant C fixation and growth, and may lead to carbon starvation [11,12]. Despite our understanding of drought response physiology we lack basic information regarding the genetic mechanisms underlying the regulation of plant metabolism and gas-exchange during drought and recovery from drought [15,17,18]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
