Proteomic Responses to Elevated Carbon Dioxide in Relation to Drought Tolerance in Creeping Bentgrass (Agrostis stolonifera).

Atmospheric carbon dioxide (CO₂) levels continue to rise and are predicted to double over the next century.  Previous studies have shown that elevated CO₂ can mitigate damaging effects of drought stress in creeping bentgrass (Agrostis stolonifera L.) but the mechanisms of this improved drought tolerance are not fully understood.  The objective of this study was to examine which specific proteins or related metabolic processes may be altered by elevated CO₂ and the consequential effect on whole-plant drought tolerance.  Creeping bentgrass (‘Penncross’) plants established from tillers were grown for five weeks in elevated (800±10 ppm) CO₂ or ambient (400±10 ppm) CO₂ and subsequently exposed to drought stress by withholding irrigation for twenty days (SWC >7.0%).  The level of drought stress was assessed four times during water-withholding by measuring leaf relative water content, electrolyte leakage, chlorophyll content, photochemical efficiency, and visual evaluation of turf quality.  Leaf samples were collected at 16 d drought stress for protein separation using two-dimensional polyacrylamide gel electrophoresis and protein identification with mass spectrometry in order to determine changes in protein abundance as affected by elevated CO₂ with or without drought stress.  Proteomic analysis demonstrated that elevated CO₂ altered the expression of proteins related to metabolism, energy production, and stress defense, which may contribute to the improved drought tolerance under elevated CO₂.  Future work may continue to investigate molecular aspects associated with enhanced drought tolerance of creeping bentgrass under elevated CO₂.