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    Rights statement: This is the author’s version of a work that was accepted for publication in Environmental and Experimental Botany. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Environmental and Experimental Botany, 149, 2018 DOI: 10.1016/j.envexpbot.2017.10.027

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Flexibility of C 4 decarboxylation and photosynthetic plasticity in sugarcane plants under shading

Research output: Contribution to journalJournal article

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  • Cristina R. G. Sales
  • Rafael Vasconcelos Ribeiro
  • Adriana Hayashi
  • Paulo Eduardo Ribeiro Marchiori
  • Karina Iolanda Silva
  • Marcio Oliveira Martins
  • Joaquim Albenisio Gomes Silveira
  • Neidiquele Maria Silveira
  • Eduardo Caruso Machado
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<mark>Journal publication date</mark>05/2018
<mark>Journal</mark>Environmental and Experimental Botany
Volume149
Number of pages9
Pages (from-to)34-42
Publication statusPublished
Early online date2/11/17
Original languageEnglish

Abstract

The flexibility between C4 photosynthetic sub-types NADP-malic enzyme (NADP-ME) and phosphoenolpyruvate carboxykinase (PEPCK), recently identified in some C4 species, confers high photosynthetic efficiency under varying light conditions. Theoretically, PEPCK decarboxylation uses less quanta per CO2 fixed than NADP-ME, suggesting an increase in PEPCK activity could be advantageous under shading, as CO2 leakiness increases under low light. Thus, we hypothesize that sugarcane plants have flexibility among the decarboxylation pathways, i.e., more than one decarboxylation route occurs independent of the environmental condition; furthermore, low light availability induces biochemical and anatomical adjustments resulting in increased PEPCK activity, which could contribute to maintaining or even increasing quantum efficiency of CO2 assimilation under limiting light. Two sugarcane varieties were evaluated and both presented activities of the three decarboxylases, either under full sunlight or shading. In vitro PEPCK activity increased in plants grown under low light, suggesting an upregulation of this decarboxylation pathway. Accordingly, changes in chloroplast arrangement of bundle sheath cells from centrifugal to evenly distributed were found. Our data suggest that such biochemical and anatomical adjustments found in sugarcane grown under shading were important to maintain the maximum quantum efficiency of CO2 assimilation. Finally, we propose a model highlighting the integration between the decarboxylation pathways under shading, considering carboxylation and decarboxylation pathways in sugarcane plants.

Bibliographic note

This is the author’s version of a work that was accepted for publication in Environmental and Experimental Botany. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Environmental and Experimental Botany, 149, 2018 DOI: 10.1016/j.envexpbot.2017.10.027