Feeling the heat: Long-term heat stress impairs growth but not photosynthesis in a C4 grass

Long-term heat stress negatively affects plants in multiple ways, including reducing the stability of photosynthetic and other proteins and enhancing photorespiration. In photorespiration, the carbon fixing enzyme Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) uses O2 as a substrate instead of CO2, thus suppressing carbon fixation Some plants that evolved under photorespiration-favoring conditions, such as high temperatures, developed C4 photosynthetic metabolism that reduces photorespiration. In C4 metabolism, CO2 is actively concentrated near Rubisco, increasing the likelihood of Rubisco interacting with CO2 instead of O2 (Sage 2004). However, despite their high photosynthetic efficiency under heat stress, the effects of extreme weather events such as heat waves on C4 plants are unclear.