Project description:In this study we were interested in identifying the gene networks that are responsive to chronic heat treatment in a switchgrass cultivar that is widely grown in the south-western USA and where 38C day temperatures have been reported for more than 100 days in the recent years. Switchgrass Alamo plants were subjected to chronic heat stress for 50 days (38 C/30C; day/night) or maintained under optimal conditions (28C/20C). Leaves were collected at the end of the heat regime for transcriptome analysis.
Project description:Sustainable production of switchgrass (Panicum virgatum) as a bioenergy crop hinges in part on efficient use of soil macronutrients, especially nitrogen (N). This study investigated the physiological, metabolic and transcriptomic responses of switchgrass to N limitation. Moderate N limitation marked a tipping point for large changes in plant growth, root-to-shoot ratio, root system architecture and total nitrogen content. Integration of transcriptomic and metabolic data revealed that N limitation reduced switchgrass photosynthetic capacity and carbon(C)-fixation activities. Switchgrass balanced C-fixation with N-assimilation, transport and recycling of N compounds by rerouting C-flux from glycolysis, the oxidative branch of the pentose phosphate pathway (OPPP) and from the tricarboxylic acid (TCA) cycle in an organ specific manner. The energy and reduction power so generated, and C-skeletons appear to be directed towards N uptake, biosynthesis of energy storage compounds with high C/N ratio such as sucrose, non-N-containing lipids, and various branches of secondary metabolism.
