Expression of a co2-permeable aquaporin enhances mesophyll conductance in the c4 species setaria viridis

Maria Ermakova; Hannah Osborn; Michael Groszmann; Soumi Bala; Andrew Bowerman; Samantha McGaughey; Caitlin Byrt; Hugo Alonso-Cantabrana; Steve Tyerman; Robert T. Furbank; Robert E. Sharwood; Susanne von Caemmerer

doi:10.7554/eLife.70095

Expression of a co₂-permeable aquaporin enhances mesophyll conductance in the c₄ species setaria viridis

Maria Ermakova^*, Hannah Osborn, Michael Groszmann, Soumi Bala, Andrew Bowerman, Samantha McGaughey, Caitlin Byrt, Hugo Alonso-Cantabrana, Steve Tyerman, Robert T. Furbank, Robert E. Sharwood^*, Susanne von Caemmerer

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

32 Citations (Scopus)

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.

Original language	English
Article number	e70095
Journal	eLife
Volume	10
DOIs	https://doi.org/10.7554/eLife.70095
Publication status	Published - Nov 2021

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10.7554/eLife.70095

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@article{379a5e944b3c467d9bc58d59d57ba410,

title = "Expression of a co2-permeable aquaporin enhances mesophyll conductance in the c4 species setaria viridis",

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.",

keywords = "Aquaporin, C photosynthesis, CO diffusion, COO discrimination, Mesophyll conductance, Setaria italica, Setaria viridis",

author = "Maria Ermakova and Hannah Osborn and Michael Groszmann and Soumi Bala and Andrew Bowerman and Samantha McGaughey and Caitlin Byrt and Hugo Alonso-Cantabrana and Steve Tyerman and Furbank, {Robert T.} and Sharwood, {Robert E.} and {von Caemmerer}, Susanne",

year = "2021",

month = nov,

doi = "10.7554/eLife.70095",

language = "English",

volume = "10",

journal = "eLife",

issn = "2050-084X",

publisher = "eLife Sciences Publications",

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TY - JOUR

T1 - Expression of a co2-permeable aquaporin enhances mesophyll conductance in the c4 species setaria viridis

AU - Ermakova, Maria

AU - Osborn, Hannah

AU - Groszmann, Michael

AU - Bala, Soumi

AU - Bowerman, Andrew

AU - McGaughey, Samantha

AU - Byrt, Caitlin

AU - Alonso-Cantabrana, Hugo

AU - Tyerman, Steve

AU - Furbank, Robert T.

AU - Sharwood, Robert E.

AU - von Caemmerer, Susanne

PY - 2021/11

Y1 - 2021/11

N2 - 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.

AB - 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.

KW - Aquaporin

KW - C photosynthesis

KW - CO diffusion

KW - COO discrimination

KW - Mesophyll conductance

KW - Setaria italica

KW - Setaria viridis

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U2 - 10.7554/eLife.70095

DO - 10.7554/eLife.70095

M3 - Article

SN - 2050-084X

VL - 10

JO - eLife

JF - eLife

M1 - e70095

ER -

Expression of a co₂-permeable aquaporin enhances mesophyll conductance in the c₄ species setaria viridis

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