Carotenoid crystal formation in Arabidopsis and carrot roots caused by increased phytoene synthase protein levels.

<h4>Background</h4>As the first pathway-specific enzyme in carotenoid biosynthesis, phytoene synthase (PSY) is a prime regulatory target. This includes a number of biotechnological approaches that have successfully increased the carotenoid content in agronomically relevant non-green plan...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	Dirk Maass, Jacobo Arango, Florian Wüst, Peter Beyer, Ralf Welsch
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2009
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/05b22d18cf1e49eaa80ebcea38f94535
Etiquetas:	Agregar Etiqueta Sin Etiquetas, Sea el primero en etiquetar este registro!

id	oai:doaj.org-article:05b22d18cf1e49eaa80ebcea38f94535
record_format	dspace
spelling	oai:doaj.org-article:05b22d18cf1e49eaa80ebcea38f945352021-11-25T06:21:23ZCarotenoid crystal formation in Arabidopsis and carrot roots caused by increased phytoene synthase protein levels.1932-620310.1371/journal.pone.0006373https://doaj.org/article/05b22d18cf1e49eaa80ebcea38f945352009-07-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/19636414/pdf/?tool=EBIhttps://doaj.org/toc/1932-6203<h4>Background</h4>As the first pathway-specific enzyme in carotenoid biosynthesis, phytoene synthase (PSY) is a prime regulatory target. This includes a number of biotechnological approaches that have successfully increased the carotenoid content in agronomically relevant non-green plant tissues through tissue-specific PSY overexpression. We investigated the differential effects of constitutive AtPSY overexpression in green and non-green cells of transgenic Arabidopsis lines. This revealed striking similarities to the situation found in orange carrot roots with respect to carotenoid amounts and sequestration mechanism.<h4>Methodology/principal findings</h4>In Arabidopsis seedlings, carotenoid content remained unaffected by increased AtPSY levels although the protein was almost quantitatively imported into plastids, as shown by western blot analyses. In contrast, non-photosynthetic calli and roots overexpressing AtPSY accumulated carotenoids 10 and 100-fold above the corresponding wild-type tissues and contained 1800 and 500 microg carotenoids per g dry weight, respectively. This increase coincided with a change of the pattern of accumulated carotenoids, as xanthophylls decreased relative to beta-carotene and carotene intermediates accumulated. As shown by polarization microscopy, carotenoids were found deposited in crystals, similar to crystalline-type chromoplasts of non-green tissues present in several other taxa. In fact, orange-colored carrots showed a similar situation with increased PSY protein as well as carotenoid levels and accumulation patterns whereas wild white-rooted carrots were similar to Arabidopsis wild type roots in this respect. Initiation of carotenoid crystal formation by increased PSY protein amounts was further confirmed by overexpressing crtB, a bacterial PSY gene, in white carrots, resulting in increased carotenoid amounts deposited in crystals.<h4>Conclusions</h4>The sequestration of carotenoids into crystals can be driven by the functional overexpression of one biosynthetic enzyme in non-green plastids not requiring a chromoplast developmental program as this does not exist in Arabidopsis. Thus, PSY expression plays a major, rate-limiting role in the transition from white to orange-colored carrots.Dirk MaassJacobo ArangoFlorian WüstPeter BeyerRalf WelschPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 4, Iss 7, p e6373 (2009)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Dirk Maass Jacobo Arango Florian Wüst Peter Beyer Ralf Welsch Carotenoid crystal formation in Arabidopsis and carrot roots caused by increased phytoene synthase protein levels.
description	<h4>Background</h4>As the first pathway-specific enzyme in carotenoid biosynthesis, phytoene synthase (PSY) is a prime regulatory target. This includes a number of biotechnological approaches that have successfully increased the carotenoid content in agronomically relevant non-green plant tissues through tissue-specific PSY overexpression. We investigated the differential effects of constitutive AtPSY overexpression in green and non-green cells of transgenic Arabidopsis lines. This revealed striking similarities to the situation found in orange carrot roots with respect to carotenoid amounts and sequestration mechanism.<h4>Methodology/principal findings</h4>In Arabidopsis seedlings, carotenoid content remained unaffected by increased AtPSY levels although the protein was almost quantitatively imported into plastids, as shown by western blot analyses. In contrast, non-photosynthetic calli and roots overexpressing AtPSY accumulated carotenoids 10 and 100-fold above the corresponding wild-type tissues and contained 1800 and 500 microg carotenoids per g dry weight, respectively. This increase coincided with a change of the pattern of accumulated carotenoids, as xanthophylls decreased relative to beta-carotene and carotene intermediates accumulated. As shown by polarization microscopy, carotenoids were found deposited in crystals, similar to crystalline-type chromoplasts of non-green tissues present in several other taxa. In fact, orange-colored carrots showed a similar situation with increased PSY protein as well as carotenoid levels and accumulation patterns whereas wild white-rooted carrots were similar to Arabidopsis wild type roots in this respect. Initiation of carotenoid crystal formation by increased PSY protein amounts was further confirmed by overexpressing crtB, a bacterial PSY gene, in white carrots, resulting in increased carotenoid amounts deposited in crystals.<h4>Conclusions</h4>The sequestration of carotenoids into crystals can be driven by the functional overexpression of one biosynthetic enzyme in non-green plastids not requiring a chromoplast developmental program as this does not exist in Arabidopsis. Thus, PSY expression plays a major, rate-limiting role in the transition from white to orange-colored carrots.
format	article
author	Dirk Maass Jacobo Arango Florian Wüst Peter Beyer Ralf Welsch
author_facet	Dirk Maass Jacobo Arango Florian Wüst Peter Beyer Ralf Welsch
author_sort	Dirk Maass
title	Carotenoid crystal formation in Arabidopsis and carrot roots caused by increased phytoene synthase protein levels.
title_short	Carotenoid crystal formation in Arabidopsis and carrot roots caused by increased phytoene synthase protein levels.
title_full	Carotenoid crystal formation in Arabidopsis and carrot roots caused by increased phytoene synthase protein levels.
title_fullStr	Carotenoid crystal formation in Arabidopsis and carrot roots caused by increased phytoene synthase protein levels.
title_full_unstemmed	Carotenoid crystal formation in Arabidopsis and carrot roots caused by increased phytoene synthase protein levels.
title_sort	carotenoid crystal formation in arabidopsis and carrot roots caused by increased phytoene synthase protein levels.
publisher	Public Library of Science (PLoS)
publishDate	2009
url	https://doaj.org/article/05b22d18cf1e49eaa80ebcea38f94535
work_keys_str_mv	AT dirkmaass carotenoidcrystalformationinarabidopsisandcarrotrootscausedbyincreasedphytoenesynthaseproteinlevels AT jacoboarango carotenoidcrystalformationinarabidopsisandcarrotrootscausedbyincreasedphytoenesynthaseproteinlevels AT florianwust carotenoidcrystalformationinarabidopsisandcarrotrootscausedbyincreasedphytoenesynthaseproteinlevels AT peterbeyer carotenoidcrystalformationinarabidopsisandcarrotrootscausedbyincreasedphytoenesynthaseproteinlevels AT ralfwelsch carotenoidcrystalformationinarabidopsisandcarrotrootscausedbyincreasedphytoenesynthaseproteinlevels
_version_	1718413783518412800

Carotenoid crystal formation in Arabidopsis and carrot roots caused by increased phytoene synthase protein levels.

Ejemplares similares