Universität zu Köln

Hilgers, Elke J. A., Schoettler, Mark Aurel, Mettler-Altmann, Tabea, Krueger, Stephan ORCID: 0000-0002-1658-5993, Doermann, Peter, Eicks, Michael, Fluegge, Ulf-Ingo and Haeusler, Rainer E. (2018). The Combined Loss of Triose Phosphate and Xylulose 5-Phosphate/Phosphate Translocators Leads to Severe Growth Retardation and Impaired Photosynthesis in Arabidopsis thaliana tpt/xpt Double Mutants. Front. Plant Sci., 9. LAUSANNE: FRONTIERS MEDIA SA. ISSN 1664-462X

Full text not available from this repository.

Abstract

The xylulose 5-phosphate/phosphate translocator (XPT) represents the fourth functional member of the phosphate translocator (PT) family residing in the plastid inner envelope membrane. In contrast to the other three members, little is known on the physiological role of the XPT. Based on its major transport substrates (i.e., pentose phosphates) the XPT has been proposed to act as a link between the plastidial and extraplastidial branches of the oxidative pentose phosphate pathway (OPPP). As the XPT is also capable of transporting those phosphates, it might as well support the triose phosphate PT (TPT) in exporting photoassimilates from the chloroplast in the light ('day path of carbon') and hence in supplying the whole plant with carbohydrates. Two independent knockout mutant alleles of the XPT (xpt-1 and xpt-2) lacked any specific phenotype, suggesting that the XPT function is redundant. However, double mutants generated from crossings of xpt-1 to different mutant alleles of the TPT (tpt-1 and tpt-2) were severely retarded in size, exhibited a high chlorophyll fluorescence phenotype, and impaired photosynthetic electron transport rates. In the double mutant the export of triose phosphates from the chloroplasts is completely blocked. Hence, precursors for sucrose biosynthesis derive entirely from starch turnover Might path of carbon'), which was accompanied by a marked accumulation of maltose as a starch breakdown product. Moreover, pentose phosphates produced by the extraplastidial branch of the OPPP also accumulated in the double mutants. Thus, an active XPT indeed retrieves excessive pentose phosphates from the extra-plastidial space and makes them available to the plastids. Further metabolic profiling revealed that phosphorylated intermediates remained largely unaffected, whereas fumarate and glycine contents were diminished in the double mutants. The assessment of C/N-ratios suggested co-limitations of C- and N-metabolism as possible cause for growth retardation of the double mutants. Feeding of sucrose partially rescued the growth and photosynthesis phenotypes of the double mutants. lmmunoblots of thylakoid proteins, spectroscopic determinations of photosynthesis complexes, and chlorophyll a fluorescence emission spectra at 77 Kelvin could only partially explain constrains in photosynthesis observed in the double mutants. The data are discussed together with aspects of the OPPP and central carbon metabolism.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Hilgers, Elke J. A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Schoettler, Mark Aurel UNSPECIFIED UNSPECIFIED UNSPECIFIED Mettler-Altmann, Tabea UNSPECIFIED UNSPECIFIED UNSPECIFIED Krueger, Stephan UNSPECIFIED orcid.org/0000-0002-1658-5993 UNSPECIFIED Doermann, Peter UNSPECIFIED UNSPECIFIED UNSPECIFIED Eicks, Michael UNSPECIFIED UNSPECIFIED UNSPECIFIED Fluegge, Ulf-Ingo UNSPECIFIED UNSPECIFIED UNSPECIFIED Haeusler, Rainer E. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-169691
DOI:	10.3389/fpls.2018.01331
Journal or Publication Title:	Front. Plant Sci.
Volume:	9
Date:	2018
Publisher:	FRONTIERS MEDIA SA
Place of Publication:	LAUSANNE
ISSN:	1664-462X
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Biology > Botanical Institute
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language NUCLEAR GENE-EXPRESSION; HIGH LIGHT INTENSITIES; AMINO-ACIDS; PHOSPHATE/PHOSPHATE TRANSLOCATOR; CHLOROPHYLL FLUORESCENCE; PLANTS BIOSYNTHESIS; ELECTRON-TRANSPORT; CARBON METABOLISM; STARCH BREAKDOWN; KNOCK-OUT Multiple languages Plant Sciences Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/16969