Expression of a CO2-permeable aquaporin enhances mesophyll conductance in the C4 species Setaria viridis

eLife

Steve Tyerman¹  Maria Ermakova²  Soumi Bala²  Hugo Alonso-cantabrana²  Samantha McGaughey²  Robert T Furbank²  Caitlin Byrt²  Hannah Osborn²  Michael Groszmann²  Andrew Bowerman²  Susanne von Caemmerer²  Robert E Sharwood³ 

[1] ARC Centre of Excellence in Plant Energy Biology, School of Agriculture Food and Wine, University of Adelaide, Adelaide, Australia;Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Science, Research School of Biology, Canberra, Australia;Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Science, Research School of Biology, Canberra, Australia;Hawkesbury Institute for the Environment, Western Sydney University, Richmond, Australia;

关键词: Setaria viridis;    Setaria italica;    aquaporin;    mesophyll conductance;    c4 photosynthesis;    co2 diffusion;    Xenopus;    S. cerevisiae;   

DOI  :  10.7554/eLife.70095

来源: eLife Sciences Publications, Ltd

【 摘 要 】

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 Setaria 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.

【 授权许可】

CC BY