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BETA-AMYLASE9 is a plastidial nonenzymatic regulator of leaf starch degradation

β-Amylases (BAMs) are key enzymes of transitory starch degradation in chloroplasts, a process that buffers the availability of photosynthetically fixed carbon over the diel cycle to maintain energy levels and plant growth at night. However, during vascular plant evolution, the BAM gene family divers...

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Autores principales: David, Laure C, Lee, Sang-Kyu, Bruderer, Eduard, Abt, Melanie R, Fischer-Stettler, Michaela, Tschopp, Marie-Aude, Solhaug, Erik M, Sanchez, Katarzyna, Zeeman, Samuel C
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8774843/
https://www.ncbi.nlm.nih.gov/pubmed/34662400
http://dx.doi.org/10.1093/plphys/kiab468
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author David, Laure C
Lee, Sang-Kyu
Bruderer, Eduard
Abt, Melanie R
Fischer-Stettler, Michaela
Tschopp, Marie-Aude
Solhaug, Erik M
Sanchez, Katarzyna
Zeeman, Samuel C
author_facet David, Laure C
Lee, Sang-Kyu
Bruderer, Eduard
Abt, Melanie R
Fischer-Stettler, Michaela
Tschopp, Marie-Aude
Solhaug, Erik M
Sanchez, Katarzyna
Zeeman, Samuel C
author_sort David, Laure C
collection PubMed
description β-Amylases (BAMs) are key enzymes of transitory starch degradation in chloroplasts, a process that buffers the availability of photosynthetically fixed carbon over the diel cycle to maintain energy levels and plant growth at night. However, during vascular plant evolution, the BAM gene family diversified, giving rise to isoforms with different compartmentation and biological activities. Here, we characterized BETA-AMYLASE 9 (BAM9) of Arabidopsis (Arabidopsis thaliana). Among the BAMs, BAM9 is most closely related to BAM4 but is more widely conserved in plants. BAM9 and BAM4 share features including their plastidial localization and lack of measurable α-1,4-glucan hydrolyzing capacity. BAM4 is a regulator of starch degradation, and bam4 mutants display a starch-excess phenotype. Although bam9 single mutants resemble the wild-type (WT), genetic experiments reveal that the loss of BAM9 markedly enhances the starch-excess phenotypes of mutants already impaired in starch degradation. Thus, BAM9 also regulates starch breakdown, but in a different way. Interestingly, BAM9 gene expression is responsive to several environmental changes, while that of BAM4 is not. Furthermore, overexpression of BAM9 in the WT reduced leaf starch content, but overexpression in bam4 failed to complement fully that mutant’s starch-excess phenotype, suggesting that BAM9 and BAM4 are not redundant. We propose that BAM9 activates starch degradation, helping to manage carbohydrate availability in response to fluctuations in environmental conditions. As such, BAM9 represents an interesting gene target to explore in crop species.
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spelling pubmed-87748432022-01-21 BETA-AMYLASE9 is a plastidial nonenzymatic regulator of leaf starch degradation David, Laure C Lee, Sang-Kyu Bruderer, Eduard Abt, Melanie R Fischer-Stettler, Michaela Tschopp, Marie-Aude Solhaug, Erik M Sanchez, Katarzyna Zeeman, Samuel C Plant Physiol Research Articles β-Amylases (BAMs) are key enzymes of transitory starch degradation in chloroplasts, a process that buffers the availability of photosynthetically fixed carbon over the diel cycle to maintain energy levels and plant growth at night. However, during vascular plant evolution, the BAM gene family diversified, giving rise to isoforms with different compartmentation and biological activities. Here, we characterized BETA-AMYLASE 9 (BAM9) of Arabidopsis (Arabidopsis thaliana). Among the BAMs, BAM9 is most closely related to BAM4 but is more widely conserved in plants. BAM9 and BAM4 share features including their plastidial localization and lack of measurable α-1,4-glucan hydrolyzing capacity. BAM4 is a regulator of starch degradation, and bam4 mutants display a starch-excess phenotype. Although bam9 single mutants resemble the wild-type (WT), genetic experiments reveal that the loss of BAM9 markedly enhances the starch-excess phenotypes of mutants already impaired in starch degradation. Thus, BAM9 also regulates starch breakdown, but in a different way. Interestingly, BAM9 gene expression is responsive to several environmental changes, while that of BAM4 is not. Furthermore, overexpression of BAM9 in the WT reduced leaf starch content, but overexpression in bam4 failed to complement fully that mutant’s starch-excess phenotype, suggesting that BAM9 and BAM4 are not redundant. We propose that BAM9 activates starch degradation, helping to manage carbohydrate availability in response to fluctuations in environmental conditions. As such, BAM9 represents an interesting gene target to explore in crop species. Oxford University Press 2021-10-18 /pmc/articles/PMC8774843/ /pubmed/34662400 http://dx.doi.org/10.1093/plphys/kiab468 Text en © The Author(s) 2021. Published by Oxford University Press on behalf of American Society of Plant Biologists. https://creativecommons.org/licenses/by/4.0/This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research Articles
David, Laure C
Lee, Sang-Kyu
Bruderer, Eduard
Abt, Melanie R
Fischer-Stettler, Michaela
Tschopp, Marie-Aude
Solhaug, Erik M
Sanchez, Katarzyna
Zeeman, Samuel C
BETA-AMYLASE9 is a plastidial nonenzymatic regulator of leaf starch degradation
title BETA-AMYLASE9 is a plastidial nonenzymatic regulator of leaf starch degradation
title_full BETA-AMYLASE9 is a plastidial nonenzymatic regulator of leaf starch degradation
title_fullStr BETA-AMYLASE9 is a plastidial nonenzymatic regulator of leaf starch degradation
title_full_unstemmed BETA-AMYLASE9 is a plastidial nonenzymatic regulator of leaf starch degradation
title_short BETA-AMYLASE9 is a plastidial nonenzymatic regulator of leaf starch degradation
title_sort beta-amylase9 is a plastidial nonenzymatic regulator of leaf starch degradation
topic Research Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8774843/
https://www.ncbi.nlm.nih.gov/pubmed/34662400
http://dx.doi.org/10.1093/plphys/kiab468
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