Overexpressing the CGR3 gene in a model crop led to a remarkable 8% increase in photosynthesis.

It is possible to engineer increased mesophyll conductance in plants according to research from the Realizing Increased Photosynthetic Efficiency (RIPE) project. Mesophyll conductance refers to the ease with which CO2 can move through a leaf’s cells before being turned into sugar (plant food). CO2 faces barriers as it moves through the leaf, including its own cell walls. Researchers recently found that by increasing porosity and reducing cell wall thickness, they could increase CO2 diffusion and uptake in a model crop.

“This is one of the few successful tests of concept showing we can engineer an increase in mesophyll conductance and have it result in increased photosynthesis in the field,” said Coralie Salesse-Smith, a postdoctoral researcher and lead author on a paper about the research, recently published in Plant Biotechnology Journal.

Mesophyll conductance is a key component in photosynthesis, the process all plants use to convert sunlight, water, and carbon dioxide into energy and yields. In order for CO2 to reach the chloroplast (where it is turned into sugar), it travels through barriers like the cell wall.  Thinner cell walls are associated with higher mesophyll conductance suggesting that decreasing wall thickness could change how easily CO2 moves into cells, potentially boosting photosynthesis.

A gene shown to alter cell wall components, CGR3, was inserted into a model crop and planted in a field trial. The plants overexpressing CGR3 showed a 7-13% decrease in cell wall thickness and a 75% increase in the ability of CO2 to move through the cell wall compared to the plants without the gene (wildtype). Together, these changes increased mesophyll conductance, resulting in an 8% increase in photosynthesis.

Photosynthetic rates were significantly increased in plants with altered cell walls relative to the unaltered plants (wildtype controls).

“This modification worked in a model crop, but it is important to test what happens in soybean to see if the same improvements will be achieved and if that leads to improvements in yield,” said Salesse-Smith.

Read the article:
Salesse‐Smith, C. E., Lochocki, E. B., Doran, L., Haas, B. E., Stutz, S. S., & Long, S. P. (2024). Greater mesophyll conductance and leaf photosynthesis in the field through modified cell wall porosity and thickness via atcgr3 expression in tobacco. Plant Biotechnology Journal. Available at: https://doi.org/10.1111/pbi.14364

A smiling Allie Arp

Allie Arp is the communications manager for the Realizing Increased Photosynthetic Efficiency (RIPE) project at the University of Illinois. For RIPE, Allie develops and implements a communications strategy to promote the work of RIPE researchers through web, print, social, and earned media. Allie earned her bachelor’s degree in public relations/professional writing from the University of Northern Iowa and later went on to receive her master’s degree in mass communications & journalism/agricultural education from Iowa State University. She has more than a decade of research communications experience.

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