No evidence for triose phosphate limitation of light saturated leaf photosynthesis under current atmospheric Co2 concentration

Abstract

The triose phosphate utilization (TPU) rate has been identified as one of the processes that can limit terrestrial plant photosynthesis. However, we lack a robust quantitative assessment of TPU limitation of photosynthesis at the global scale. As a result, TPU, and its potential limitation of photosynthesis, is poorly represented in terrestrial bio- sphere models (TBMs). In this study, we utilized a global data set of photosynthetic CO 2 response curves representing 141 species from tropical rainforests to Arctic tun- dra. We quantified TPU by fitting the standard biochemical model of C 3 photosynthe- sis to measured photosynthetic CO 2 response curves and characterized its instantaneous temperature response. Our results demonstrate that TPU does not limit leaf photosynthesis at the current ambient atmospheric CO2 concentration. Further- more, our results showed that the light‐saturated photosynthetic rates of plants growing in cold environments are not more often limited by TPU than those of plants growing in warmer environments. In addition, our study showed that the instanta- neous temperature response of TPU is distinct from temperature response of the maximum rate of Rubisco carboxylation. The new formulations of the temperature response of TPU derived in this study may prove useful in quantifying the biochemical limits to terrestrial plant photosynthesis and improve the representation of plant pho- tosynthesis in TBMs