Transcriptome Response to Elevated CO2, Water Deficit, and Thermal Stress in Peanut.

Previously, our laboratories have performed gene expression studies using EST sequencing and spotted microarrays to investigate tissue-specific gene expression and response to abiotic stress. While these studies have provided valuable insight into these processes, they are constrained by sequencer throughput, expense, or require a priori information about gene sequence and function. RNA sequencing (RNA-seq) is an open architecture gene expression technology that eliminates many of these problems and allows for the identification of new gene sequences while providing robust gene expression information. We examined the interactive effects of long term exposure to elevated [CO₂] (ambient + 250ppm) and water deficit on physiological and molecular responses, in a peanut (C-7616) runner market type, grown in field conditions. A comparative leaf transcriptomic profile across three periodic water deficit/re-hydration cycles through the growing season was evaluated using RNA-seq analysis. Six data points (pre-water stress, early and late water deficit, and re-hydration events were selected. Results show significantly differential gene expression between and within [CO₂] treatments at different water availability stages. Mercator annotation analysis shows that lipid metabolism, hormone biosynthesis, secondary metabolism, amino acid biosynthesis and transport, are among the most impacted biological processes by the combined abiotic stresses addressed in this study. Overall, the number of differentially expressed genes increased overtime, and was more pronounced in plants grown at ambient versus elevated [CO₂] conditions. A detailed analysis of differential expression by treatment and stages will be presented.