Author: Robert Guy
Published in: Plant, Cell & Environment
Substantial role for carbonic anhydrase in latitudinal variation in mesophyll conductance of Populus trichocarpa Torr. & Gray
Carbonic anhydrase is the second most abundant protein in plants, and therefore is quite possibly the second most abundant protein on Earth. Surprisingly, it’s functional role in plants has never been fully understood. Though long suspected, we provide the first empirical evidence (in any plant) of an important role for carbonic anhydrase in photosynthesis. We demonstrate that higher photosynthetic rates in black cottonwood trees from higher latitudes are supported by higher carbonic anhydrase activities.
Using two independent methods and a chemical inhibitor, we show that carbonic anhydrase activity is tightly correlated with differences in mesophyll conductance (i.e., the “ease” with which carbon dioxide diffuses into photosynthetic cells). Carbonic anhydrase promotes photosynthesis by helping to maintain dissolved CO2 concentrations, thereby sustaining diffusion. These findings will focus crop improvement efforts on carbonic anhydrase activity to improve growth and yield, as well as resource use efficiencies for both water and nitrogen.
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