Abstract |
- BACKGROUND: 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. 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.
RESULTS: Soil 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.
CONCLUSIONS: Our 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.
- Keywords: RNA-seq, Drought, Panicum virgatum, Gene expression, Switchgrass, Recovery
- Keywords: RNA-seq, Drought, Panicum virgatum, Gene expression, Switchgrass, Recovery
- Keywords: RNA-seq, Drought, Panicum virgatum, Gene expression, Switchgrass, Recovery
- Keywords: RNA-seq, Drought, Panicum virgatum, Gene expression, Switchgrass, Recovery
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