Journal article
Diffusion of CO 2 across the Mesophyll-Bundle Sheath Cell Interface in a C 4 Plant with Genetically Reduced PEP Carboxylase Activity
Plant physiology (Bethesda), Vol.178(1), pp.72-81
09/2018
Handle:
https://hdl.handle.net/2376/115616
PMID: 30018172
Abstract
Phospho
pyruvate carboxylase (PEPC), localized to the cytosol of the mesophyll cell, catalyzes the first carboxylation step of the C
photosynthetic pathway. Here, we used RNA interference to target the cytosolic photosynthetic PEPC isoform in
and isolated independent transformants with very low PEPC activities. These plants required high ambient CO
concentrations for growth, consistent with the essential role of PEPC in C
photosynthesis. The combination of estimating direct CO
fixation by the bundle sheath using gas-exchange measurements and modeling C
photosynthesis with low PEPC activity allowed the calculation of bundle sheath conductance to CO
diffusion (
) in the progeny of these plants. Measurements made at a range of temperatures suggested no or negligible effect of temperature on
depending on the technique used to calculate
Anatomical measurements revealed that plants with reduced PEPC activity had reduced cell wall thickness and increased plasmodesmata (PD) density at the mesophyll-bundle sheath (M-BS) cell interface, whereas we observed little difference in these parameters at the mesophyll-mesophyll cell interface. The increased PD density at the M-BS interface was largely driven by an increase in the number of PD pit fields (cluster of PDs) rather than an increase in PD per pit field or the size of pit fields. The correlation of
with bundle sheath surface area per leaf area and PD area per M-BS area showed that these parameters and cell wall thickness are important determinants of
It is intriguing to speculate that PD development is responsive to changes in C
photosynthetic flux.
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Details
- Title
- Diffusion of CO 2 across the Mesophyll-Bundle Sheath Cell Interface in a C 4 Plant with Genetically Reduced PEP Carboxylase Activity
- Creators
- Hugo Alonso-Cantabrana - Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, AustraliaAsaph B Cousins - School of Biological Sciences, Molecular Plant Sciences, Washington State University, Pullman, Washington 99164-4236Florence Danila - Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, AustraliaTimothy Ryan - Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, AustraliaRobert E Sharwood - Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, AustraliaSusanne von Caemmerer - Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, Australia susanne.caemmerer@anu.edu.auRobert T Furbank - Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, Australia
- Publication Details
- Plant physiology (Bethesda), Vol.178(1), pp.72-81
- Academic Unit
- Biological Sciences, School of
- Publisher
- United States
- Identifiers
- 99900547866601842
- Language
- English
- Resource Type
- Journal article