Cell density and airspace patterning in the leaf can be manipulated to increase leaf photosynthetic capacity

Increasing photosynthetic conversion efficiency is an attractive target for improving crop yields.  One way of affecting this is to alter the way CO₂ is delivered to Rubisco, the carbon-fixing enzyme of photosynthesis.  Lehmeier et al. aimed to change the pattern of air spaces within Arabidopsis leaves by modulating the expression of the cell cycle genes KRP1 and RBR1.  They were able to manipulate mesophyll cell size, and used microCT imaging to demonstrate that this affected the architecture of air channels. These manipulations led to an increase in photosynthetic rate, which could only partially be explained by changes in leaf thickness.  Increases in Rubisco activity and mesophyll conductance were also observed, indicating that this could be a viable strategy for boosting photosynthetic assimilation. (Summary by Mike Page) Plant J. 10.1111/tpj.13727