Phloem function: a key to understanding and manipulating plant responses to rising atmospheric [CO2]?

Abstract

Increasing atmospheric carbon dioxide concentration ([CO₂]) directly stimulates photosynthesis and reduces stomatal conductance in C₃ plants. Both of these physiological effects have the potential to alter phloem function at elevated [CO₂]. Recent research has clearly established that photosynthetic capacity is correlated to vascular traits associated with phloem loading and water transport, but the effects of elevated [CO₂] on these relationships are largely unexplored. Plants also employ different strategies for loading sucrose and other sugars into the phloem, and there is potential for species with different phloem loading strategies to respond differently to elevated [CO₂]. Recent research manipulating sucrose transporters and other key enzymes with roles in phloem loading show promise for maximizing crop performance in an elevated [CO₂] world.