temperatures and analysed to determine how photosynthesis, respiration and C3–C4 features acclimate to these growth conditions. The CO2 compensation point and net rates of CO2 assimilation in cold-grown plants changed dramatically when measured in response to temperature. However, this was not due to the loss of C3–C4 intermediacy, but rather to a large increase in mitochondrial respiration supported primarily by the non-phosphorylating alternative oxidative pathway (AOP) and, to a lesser degree, the cytochrome oxidative pathway (COP). The increase in respiration and AOP capacity in cold-grown plants likely protects against reactive oxygen species (ROS) in mitochondria and photodamage in chloroplasts by consuming excess reductant via the alternative mitochondrial respiratory electron transport chain.