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NTRC and Thioredoxin f Overexpression Differentially Induces Starch Accumulation in Tobacco Leaves

Thioredoxin (Trx) f and NADPH-dependent Trx reductase C (NTRC) have both been proposed as major redox regulators of starch metabolism in chloroplasts. However, little is known regarding the specific role of each protein in this complex mechanism. To shed light on this point, tobacco plants that were...

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Autores principales: Ancín, María, Larraya, Luis, Fernández-San Millán, Alicia, Veramendi, Jon, Burch-Smith, Tessa, Farran, Inmaculada
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6963466/
https://www.ncbi.nlm.nih.gov/pubmed/31779140
http://dx.doi.org/10.3390/plants8120543
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author Ancín, María
Larraya, Luis
Fernández-San Millán, Alicia
Veramendi, Jon
Burch-Smith, Tessa
Farran, Inmaculada
author_facet Ancín, María
Larraya, Luis
Fernández-San Millán, Alicia
Veramendi, Jon
Burch-Smith, Tessa
Farran, Inmaculada
author_sort Ancín, María
collection PubMed
description Thioredoxin (Trx) f and NADPH-dependent Trx reductase C (NTRC) have both been proposed as major redox regulators of starch metabolism in chloroplasts. However, little is known regarding the specific role of each protein in this complex mechanism. To shed light on this point, tobacco plants that were genetically engineered to overexpress the NTRC protein from the chloroplast genome were obtained and compared to previously generated Trx f-overexpressing transplastomic plants. Likewise, we investigated the impact of NTRC and Trx f deficiency on starch metabolism by generating Nicotiana benthamiana plants that were silenced for each gene. Our results demonstrated that NTRC overexpression induced enhanced starch accumulation in tobacco leaves, as occurred with Trx f. However, only Trx f silencing leads to a significant decrease in the leaf starch content. Quantitative analysis of enzyme activities related to starch synthesis and degradation were determined in all of the genotypes. Zymographic analyses were additionally performed to compare the amylolytic enzyme profiles of both transplastomic tobacco plants. Our findings indicated that NTRC overexpression promotes the accumulation of transitory leaf starch as a consequence of a diminished starch turnover during the dark period, which seems to be related to a significant reductive activation of ADP-glucose pyrophosphorylase and/or a deactivation of a putative debranching enzyme. On the other hand, increased starch content in Trx f-overexpressing plants was connected to an increase in the capacity of soluble starch synthases during the light period. Taken together, these results suggest that NTRC and the ferredoxin/Trx system play distinct roles in starch turnover.
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spelling pubmed-69634662020-01-30 NTRC and Thioredoxin f Overexpression Differentially Induces Starch Accumulation in Tobacco Leaves Ancín, María Larraya, Luis Fernández-San Millán, Alicia Veramendi, Jon Burch-Smith, Tessa Farran, Inmaculada Plants (Basel) Article Thioredoxin (Trx) f and NADPH-dependent Trx reductase C (NTRC) have both been proposed as major redox regulators of starch metabolism in chloroplasts. However, little is known regarding the specific role of each protein in this complex mechanism. To shed light on this point, tobacco plants that were genetically engineered to overexpress the NTRC protein from the chloroplast genome were obtained and compared to previously generated Trx f-overexpressing transplastomic plants. Likewise, we investigated the impact of NTRC and Trx f deficiency on starch metabolism by generating Nicotiana benthamiana plants that were silenced for each gene. Our results demonstrated that NTRC overexpression induced enhanced starch accumulation in tobacco leaves, as occurred with Trx f. However, only Trx f silencing leads to a significant decrease in the leaf starch content. Quantitative analysis of enzyme activities related to starch synthesis and degradation were determined in all of the genotypes. Zymographic analyses were additionally performed to compare the amylolytic enzyme profiles of both transplastomic tobacco plants. Our findings indicated that NTRC overexpression promotes the accumulation of transitory leaf starch as a consequence of a diminished starch turnover during the dark period, which seems to be related to a significant reductive activation of ADP-glucose pyrophosphorylase and/or a deactivation of a putative debranching enzyme. On the other hand, increased starch content in Trx f-overexpressing plants was connected to an increase in the capacity of soluble starch synthases during the light period. Taken together, these results suggest that NTRC and the ferredoxin/Trx system play distinct roles in starch turnover. MDPI 2019-11-26 /pmc/articles/PMC6963466/ /pubmed/31779140 http://dx.doi.org/10.3390/plants8120543 Text en © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Ancín, María
Larraya, Luis
Fernández-San Millán, Alicia
Veramendi, Jon
Burch-Smith, Tessa
Farran, Inmaculada
NTRC and Thioredoxin f Overexpression Differentially Induces Starch Accumulation in Tobacco Leaves
title NTRC and Thioredoxin f Overexpression Differentially Induces Starch Accumulation in Tobacco Leaves
title_full NTRC and Thioredoxin f Overexpression Differentially Induces Starch Accumulation in Tobacco Leaves
title_fullStr NTRC and Thioredoxin f Overexpression Differentially Induces Starch Accumulation in Tobacco Leaves
title_full_unstemmed NTRC and Thioredoxin f Overexpression Differentially Induces Starch Accumulation in Tobacco Leaves
title_short NTRC and Thioredoxin f Overexpression Differentially Induces Starch Accumulation in Tobacco Leaves
title_sort ntrc and thioredoxin f overexpression differentially induces starch accumulation in tobacco leaves
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6963466/
https://www.ncbi.nlm.nih.gov/pubmed/31779140
http://dx.doi.org/10.3390/plants8120543
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