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Diurnal changes in storage carbohydrate metabolism in cotyledons of the tropical tree Hymenaea courbaril L. (Leguminosae)

The cotyledons of Hymenaea courbaril store large amounts of xyloglucan, a cell wall polysaccharide that is believed to serve as storage for the period of seedling establishment. During storage mobilisation, xyloglucan seems to be degraded by a continuous process that starts right after radicle protr...

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Main Authors: Amaral, Lourdes Isabel Velho do, Santos, Henrique P., Rossatto, Davi Rodrigo, Buckeridge, Marcos Silveira
Format: Artigo
Language: English
Published: Sociedade Botânica de São Paulo 2017
Subjects:
Enzimas - análise
Carboidratos - nutrição humana
Online Access: http://repositorio.unb.br/handle/10482/28361
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spelling ir-10482-283612019-03-28T14:02:51Z Diurnal changes in storage carbohydrate metabolism in cotyledons of the tropical tree Hymenaea courbaril L. (Leguminosae) Amaral, Lourdes Isabel Velho do Santos, Henrique P. Rossatto, Davi Rodrigo Buckeridge, Marcos Silveira Enzimas - análise Carboidratos - nutrição humana The cotyledons of Hymenaea courbaril store large amounts of xyloglucan, a cell wall polysaccharide that is believed to serve as storage for the period of seedling establishment. During storage mobilisation, xyloglucan seems to be degraded by a continuous process that starts right after radicle protrusion and follows up to the establishment of photosynthesis. Here we show evidence that events related to the hydrolases activities and production (α-xylosidase, β-galactosidase, β-glucosidase and xyloglucan endo-β-transglucosilase) as well as auxin, showed changes that follow the diurnal cycle. The period of higher hydrolases activities was between 6pm and 6am, which is out of phase with photosynthesis. Among the enzymes, α-xilosidase seems to be more important than β-glucosidase and β-galactosidase in the xyloglucan disassembling mechanism. Likewise, the sugars related with sucrose metabolism followed the rhythm of the hydrolases, but starch levels were shown to be practically constant. A high level of auxin was observed during the night, what is compatible with the hypothesis that this hormone would be one of the regulators of the whole process. The probable biological meaning of the existence of such a complex control mechanism during storage mobilisation is likely to be related to a remarkably high level of efficiency of carbon usage by the growing seedling of Hymenaea courbaril, allowing the establishment of very vigorous seedlings in the tropical forest. 2017-12-07T04:58:49Z 2017-12-07T04:58:49Z 2012 Artigo Braz. J. Bot.,v.35,n.4,p.347-355,2012 0100-8404 http://repositorio.unb.br/handle/10482/28361 10.1590/S0100-84042012000400008 en Acesso Aberto application/pdf Sociedade Botânica de São Paulo http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84042012000400008&lng=en&nrm=iso http://www.scielo.br/scielo.php?script=sci_abstract&pid=S0100-84042012000400008&lng=en&nrm=iso http://www.scielo.br/scielo.php?script=sci_pdf&pid=S0100-84042012000400008&lng=en&nrm=iso
institution REPOSITORIO UNB
collection REPOSITORIO UNB
language English
topic Enzimas - análise
Carboidratos - nutrição humana
spellingShingle Enzimas - análise
Carboidratos - nutrição humana
Amaral, Lourdes Isabel Velho do
Santos, Henrique P.
Rossatto, Davi Rodrigo
Buckeridge, Marcos Silveira
Diurnal changes in storage carbohydrate metabolism in cotyledons of the tropical tree Hymenaea courbaril L. (Leguminosae)
description The cotyledons of Hymenaea courbaril store large amounts of xyloglucan, a cell wall polysaccharide that is believed to serve as storage for the period of seedling establishment. During storage mobilisation, xyloglucan seems to be degraded by a continuous process that starts right after radicle protrusion and follows up to the establishment of photosynthesis. Here we show evidence that events related to the hydrolases activities and production (α-xylosidase, β-galactosidase, β-glucosidase and xyloglucan endo-β-transglucosilase) as well as auxin, showed changes that follow the diurnal cycle. The period of higher hydrolases activities was between 6pm and 6am, which is out of phase with photosynthesis. Among the enzymes, α-xilosidase seems to be more important than β-glucosidase and β-galactosidase in the xyloglucan disassembling mechanism. Likewise, the sugars related with sucrose metabolism followed the rhythm of the hydrolases, but starch levels were shown to be practically constant. A high level of auxin was observed during the night, what is compatible with the hypothesis that this hormone would be one of the regulators of the whole process. The probable biological meaning of the existence of such a complex control mechanism during storage mobilisation is likely to be related to a remarkably high level of efficiency of carbon usage by the growing seedling of Hymenaea courbaril, allowing the establishment of very vigorous seedlings in the tropical forest.
format Artigo
author Amaral, Lourdes Isabel Velho do
Santos, Henrique P.
Rossatto, Davi Rodrigo
Buckeridge, Marcos Silveira
author_sort Amaral, Lourdes Isabel Velho do
title Diurnal changes in storage carbohydrate metabolism in cotyledons of the tropical tree Hymenaea courbaril L. (Leguminosae)
title_short Diurnal changes in storage carbohydrate metabolism in cotyledons of the tropical tree Hymenaea courbaril L. (Leguminosae)
title_full Diurnal changes in storage carbohydrate metabolism in cotyledons of the tropical tree Hymenaea courbaril L. (Leguminosae)
title_fullStr Diurnal changes in storage carbohydrate metabolism in cotyledons of the tropical tree Hymenaea courbaril L. (Leguminosae)
title_full_unstemmed Diurnal changes in storage carbohydrate metabolism in cotyledons of the tropical tree Hymenaea courbaril L. (Leguminosae)
title_sort diurnal changes in storage carbohydrate metabolism in cotyledons of the tropical tree hymenaea courbaril l. (leguminosae)
publisher Sociedade Botânica de São Paulo
publishDate 2017
url http://repositorio.unb.br/handle/10482/28361
_version_ 1641988277371142144
score 13.657419

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