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Computational modelling predicts substantial carbon assimilation gains for C3 plants with a single-celled C4 biochemical pump.
- Source :
- PLoS Computational Biology; 9/30/2019, Vol. 15 Issue 9, p1-25, 25p, 1 Diagram, 1 Chart, 7 Graphs
- Publication Year :
- 2019
-
Abstract
- Achieving global food security for the estimated 9 billion people by 2050 is a major scientific challenge. Crop productivity is fundamentally restricted by the rate of fixation of atmospheric carbon. The dedicated enzyme, RubisCO, has a low turnover and poor specificity for CO<subscript>2</subscript>. This limitation of C<subscript>3</subscript> photosynthesis (the basic carbon-assimilation pathway present in all plants) is alleviated in some lineages by use of carbon-concentrating-mechanisms, such as the C<subscript>4</subscript> cycle—a biochemical pump that concentrates CO<subscript>2</subscript> near RubisCO increasing assimilation efficacy. Most crops use only C<subscript>3</subscript> photosynthesis, so one promising research strategy to boost their productivity focuses on introducing a C<subscript>4</subscript> cycle. The simplest proposal is to use the cycle to concentrate CO<subscript>2</subscript> inside individual chloroplasts. The photosynthetic efficiency would then depend on the leakage of CO<subscript>2</subscript> out of a chloroplast. We examine this proposal with a 3D spatial model of carbon and oxygen diffusion and C<subscript>4</subscript> photosynthetic biochemistry inside a typical C<subscript>3</subscript>-plant mesophyll cell geometry. We find that the cost-efficiency of C<subscript>4</subscript> photosynthesis depends on the gas permeability of the chloroplast envelope, the C<subscript>4</subscript> pathway having higher quantum efficiency than C<subscript>3</subscript> for permeabilities below 300 μm/s. However, at higher permeabilities the C<subscript>4</subscript> pathway still provides a substantial boost to carbon assimilation with only a moderate decrease in efficiency. The gains would be capped by the ability of chloroplasts to harvest light, but even under realistic light regimes a 100% boost to carbon assimilation is possible. This could be achieved in conjunction with lower investment in chloroplasts if their cell surface coverage is also reduced. Incorporation of this C<subscript>4</subscript> cycle into C<subscript>3</subscript> crops could thus promote higher growth rates and better drought resistance in dry, high-sunlight climates. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 1553734X
- Volume :
- 15
- Issue :
- 9
- Database :
- Complementary Index
- Journal :
- PLoS Computational Biology
- Publication Type :
- Academic Journal
- Accession number :
- 138873583
- Full Text :
- https://doi.org/10.1371/journal.pcbi.1007373