Expression of a CO2-permeable aquaporin enhances mesophyll conductance in the C4 species Setaria viridis
- Australian National University, Australia
- University of Adelaide, Australia
- Western Sydney University, Australia
Abstract
A fundamental limitation of photosynthetic carbon fixation is the availability of CO2. In C4 plants, primary carboxylation occurs in mesophyll cytosol, and little is known about the role of CO2 diffusion in facilitating C4 photosynthesis. We have examined the expression, localization, and functional role of selected plasma membrane intrinsic aquaporins (PIPs) from Setaria italica (foxtail millet) and discovered that SiPIP2;7 is CO2-permeable. When ectopically expressed in mesophyll cells of S. viridis (green foxtail), SiPIP2;7 was localized to the plasma membrane and caused no marked changes in leaf biochemistry. Gas-exchange and C18O16O discrimination measurements revealed that targeted expression of SiPIP2;7 enhanced the conductance to CO2 diffusion from the intercellular airspace to the mesophyll cytosol. Our results demonstrate that mesophyll conductance limits C4 photosynthesis at low pCO2 and that SiPIP2;7 is a functional CO2 permeable aquaporin that can improve CO2 diffusion at the airspace/mesophyll interface and enhance C4 photosynthesis.
Data availability
All data generated or analysed during this study are included in the manuscript and supporting files.
Article and author information
Author details
Hugo Alonso-cantabrana
Funding
Australian Research Council (Centre of Excellence for Translational Photosynthesis,CE140100015)
- Maria Ermakova
- Hannah Osborn
- Michael Groszmann
- Soumi Bala
- Hugo Alonso-cantabrana
- Robert T Furbank
- Robert E Sharwood
- Suzanne von Caemmerer
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2021, Ermakova et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Expression of a CO2-permeable aquaporin enhances mesophyll conductance in the C4 species Setaria viridis
eLife 10:e70095.
https://doi.org/10.7554/eLife.70095
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