Time of Day Analysis of Plant Responses to Abiotic Stress

Plants have an internal clock that mediates almost all daily activities. The entrainment of this circadian clock by light/warm days and dark/cold nights coordinates internal molecular responses with the environment and allows the plant to anticipate recurring environmental changes. While the regulation of the circadian clock is well studied in Arabidopsis thaliana, much less is known about the influence the circadian clock in monocot plants. Recent evidence has shown that both biotic and abiotic stress responses are dependent upon the time of day that the stress is encountered.  We are investigating the connection between time of day and abiotic stress response in Oryza sativa. Currently, we have observed that the transcriptomic, metabolomic, and phenotypic responses to abiotic stress show substantial differences in both lab and field settings when the same stress is applied at different times of day. Considering more than 80% of the transcriptome shows differential expression between day and night in a healthy, non-stressed plant (Filichkin), it is no surprise that the transcriptional response networks also vary drastically and result in a time of day dependent stress response. We believe this daily time-dependent modulation of the transcriptional landscape can be used as a powerful tool to uncover the specific relationships that link stress to resulting metabolic and physiological phenotypes. We are developing a novel bioinformatics approach, using machine-learning techniques, to take advantage of the temporal relationship between transcripts and metabolites and identify new markers for stress tolerance.