Roles of heat shock protein and reprogramming of photosynthetic carbon metabolism in thermotolerance under elevated CO2 in maize

Abstract

Our previous published results demonstrated that elevated CO2 can reprogram photosynthetic carbon metabolism (PCM) during sudden heat stress (SHS) treatments. However, the mechanism explaining how elevated CO2 could regulate the metabolites through SHS-induced proteins is poorly understood. Here, we combined metabolism and transcriptomes analysis to elucidate the differential genes expression of key heat shock proteins (HSPs) under SHS in presence of elevated CO2. Our results show strong positive correlation in terms of carbon assimilation rates (A) between both field open top chamber (OTCs) and growth chamber conditions. The decline in A during SHS is ascribable to a metabolic reprogramming rather than stomatal-limitation. We recorded an increase by about 3 ˜ 4 times in the expression levels of small HSPs, especially Cpn2 and Hsp1 following elevated CO2. This study underlines the beneficial effects of elevated CO2 in the thermotolerance process through amplifying small HSPs in maize. Our current investigation suggests a potential mechanistic model for the metabolic network reprogramming following combined effect of SHS and elevated CO2. It corroborates as well the involvement of two HSPs genes in the in the adjustment of photosynthetic carbon metabolism pathway to avoid any misfolding in Rubisco subunits proteins.