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Carbon isotope discrimination as a diagnostic tool for C(4) photosynthesis in C(3)-C(4) intermediate species

The presence and activity of the C(4) cycle in C(3)-C(4) intermediate species have proven difficult to analyze, especially when such activity is low. This study proposes a strategy to detect C(4) activity and estimate its contribution to overall photosynthesis in intermediate plants, by using tunabl...

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Autores principales: Alonso-Cantabrana, Hugo, von Caemmerer, Susanne
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4867892/
https://www.ncbi.nlm.nih.gov/pubmed/26862154
http://dx.doi.org/10.1093/jxb/erv555
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author Alonso-Cantabrana, Hugo
von Caemmerer, Susanne
author_facet Alonso-Cantabrana, Hugo
von Caemmerer, Susanne
author_sort Alonso-Cantabrana, Hugo
collection PubMed
description The presence and activity of the C(4) cycle in C(3)-C(4) intermediate species have proven difficult to analyze, especially when such activity is low. This study proposes a strategy to detect C(4) activity and estimate its contribution to overall photosynthesis in intermediate plants, by using tunable diode laser absorption spectroscopy (TDLAS) coupled to gas exchange systems to simultaneously measure the CO(2) responses of CO(2) assimilation (A) and carbon isotope discrimination (Δ) under low O(2) partial pressure. Mathematical models of C(3)-C(4) photosynthesis and Δ are then fitted concurrently to both responses using the same set of constants. This strategy was applied to the intermediate species Flaveria floridana and F. brownii, and to F. pringlei and F. bidentis as C(3) and C(4) controls, respectively. Our results support the presence of a functional C(4) cycle in F. floridana, that can fix 12–21% of carbon. In F. brownii, 75–100% of carbon is fixed via the C(4) cycle, and the contribution of mesophyll Rubisco to overall carbon assimilation increases with CO(2) partial pressure in both intermediate plants. Combined gas exchange and Δ measurement and modeling is a powerful diagnostic tool for C(4) photosynthesis.
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spelling pubmed-48678922016-05-17 Carbon isotope discrimination as a diagnostic tool for C(4) photosynthesis in C(3)-C(4) intermediate species Alonso-Cantabrana, Hugo von Caemmerer, Susanne J Exp Bot Research Paper The presence and activity of the C(4) cycle in C(3)-C(4) intermediate species have proven difficult to analyze, especially when such activity is low. This study proposes a strategy to detect C(4) activity and estimate its contribution to overall photosynthesis in intermediate plants, by using tunable diode laser absorption spectroscopy (TDLAS) coupled to gas exchange systems to simultaneously measure the CO(2) responses of CO(2) assimilation (A) and carbon isotope discrimination (Δ) under low O(2) partial pressure. Mathematical models of C(3)-C(4) photosynthesis and Δ are then fitted concurrently to both responses using the same set of constants. This strategy was applied to the intermediate species Flaveria floridana and F. brownii, and to F. pringlei and F. bidentis as C(3) and C(4) controls, respectively. Our results support the presence of a functional C(4) cycle in F. floridana, that can fix 12–21% of carbon. In F. brownii, 75–100% of carbon is fixed via the C(4) cycle, and the contribution of mesophyll Rubisco to overall carbon assimilation increases with CO(2) partial pressure in both intermediate plants. Combined gas exchange and Δ measurement and modeling is a powerful diagnostic tool for C(4) photosynthesis. Oxford University Press 2016-05 2016-02-08 /pmc/articles/PMC4867892/ /pubmed/26862154 http://dx.doi.org/10.1093/jxb/erv555 Text en © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. http://creativecommons.org/licenses/by/3.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research Paper
Alonso-Cantabrana, Hugo
von Caemmerer, Susanne
Carbon isotope discrimination as a diagnostic tool for C(4) photosynthesis in C(3)-C(4) intermediate species
title Carbon isotope discrimination as a diagnostic tool for C(4) photosynthesis in C(3)-C(4) intermediate species
title_full Carbon isotope discrimination as a diagnostic tool for C(4) photosynthesis in C(3)-C(4) intermediate species
title_fullStr Carbon isotope discrimination as a diagnostic tool for C(4) photosynthesis in C(3)-C(4) intermediate species
title_full_unstemmed Carbon isotope discrimination as a diagnostic tool for C(4) photosynthesis in C(3)-C(4) intermediate species
title_short Carbon isotope discrimination as a diagnostic tool for C(4) photosynthesis in C(3)-C(4) intermediate species
title_sort carbon isotope discrimination as a diagnostic tool for c(4) photosynthesis in c(3)-c(4) intermediate species
topic Research Paper
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4867892/
https://www.ncbi.nlm.nih.gov/pubmed/26862154
http://dx.doi.org/10.1093/jxb/erv555
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