Environmental sources of stress, including drought, cold, and salinity, can substantially affect plant fitness and survival. This poses a significant threat to conservation, economic activities, and agriculture as climate change increases the variability of temperature, precipitation, and availability of fresh water. Stress tolerance can vary widely between species and across differently adapted populations within a species. Environmental stress can decrease photosynthesis, diminish vegetative growth, and reduce reproductive output, each of which has serious consequences for agricultural and bio-energy crops. This research examines physiological and transcriptomic responses to environmental stress across populations in the wild foxtail millet, Setaria viridis, a close relative of the agriculturally important foxtail millet, Setaria italica. We assessed differences in response to cold, drought, and salinity stress between two populations of S. viridis (one from China and one from Chile) in controlled greenhouse and cold room environments. Plants from both populations were subjected to drought stress, exposed to cold stress at -5 degree Celsius with and without acclimation, and were watered with 100mmol/L or 200mmol/L NaCl solutions. After leaf tissue was collected from control and experimental plants from both populations, we extracted and sequenced RNA to compare gene expression between populations and treatments.
Results/Conclusions
Physiological responses to drought stress, measured by photosynthetic rate, differed significantly between populations. Plants from the Chile population stopped photosynthesizing due to drought stress an after an average of 13.3 days, whereas plants from the China population took 18.5 days on average. Preliminary results indicate that plant response to cold stress at -5 degrees Celsius did not differ based on prior cold acclimation or population. We are currently analyzing RNA sequence data which will allow us to compare transcriptomic and phenotypic responses by quantifying up and down regulation of genes across treatment and population. A differently expressed gene (DEG) analysis and gene ontology (GO) analysis will be used to assess differences in transcriptomic response to different types of abiotic stressors. Ultimately, this research will help determine effects of population adaptation on environmental stress response in a close relative of an important agricultural crop. Increasing knowledge of stress tolerance and adaptation in S. viridis will contribute to the broader understanding of global variation and abiotic responses for the many ecologically and agriculturally relevant species in Poaceae, which has important implications for developing more effective global conservation and agricultural production strategies.