Universität zu Köln

Zamani-Nour, Shirin, Lin, Hsiang-Chun, Walker, Berkley J., Mettler-Altmann, Tabea, Khoshravesh, Roxana ORCID: 0000-0002-1766-8993, Karki, Shanta, Bagunu, Efren, Sage, Tammy L., Quick, W. Paul and Weber, Andreas P. M. (2021). Overexpression of the chloroplastic 2-oxoglutarate/malate transporter disturbs carbon and nitrogen homeostasis in rice. J. Exp. Bot., 72 (1). S. 137 - 153. OXFORD: OXFORD UNIV PRESS. ISSN 1460-2431

Full text not available from this repository.

Abstract

The chloroplastic 2-oxaloacetate (OAA)/malate transporter (OMT1 or DiT1) takes part in the malate valve that protects chloroplasts from excessive redox poise through export of malate and import of OAA. Together with the glutamate/malate transporter (DCT1 or DiT2), it connects carbon with nitrogen assimilation, by providing 2-oxoglutarate for the GS/GOGAT (glutamine synthetase/glutamate synthase) reaction and exporting glutamate to the cytoplasm. OMT1 further plays a prominent role in C-4 photosynthesis: OAA resulting from phosphoenolpyruvate carboxylation is imported into the chloroplast, reduced to malate by plastidic NADP-malate dehydrogenase, and then exported for transport to bundle sheath cells. Both transport steps are catalyzed by OMT1, at the rate of net carbon assimilation. To engineer C-4 photosynthesis into C-3 crops, OMT1 must be expressed in high amounts on top of core C-4 metabolic enzymes. We report here high-level expression of ZmOMT1 from maize in rice (Oryza sativa ssp. indica IR64). Increased activity of the transporter in transgenic rice was confirmed by reconstitution of transporter activity into proteoliposomes. Unexpectedly, overexpression of ZmOMT1 in rice negatively affected growth, CO2 assimilation rate, total free amino acid content, tricarboxylic acid cycle metabolites, as well as sucrose and starch contents. Accumulation of high amounts of aspartate and the impaired growth phenotype of OMT1 rice lines could be suppressed by simultaneous overexpression of ZmDiT2. Implications for engineering C-4 rice are discussed.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Zamani-Nour, Shirin UNSPECIFIED UNSPECIFIED UNSPECIFIED Lin, Hsiang-Chun UNSPECIFIED UNSPECIFIED UNSPECIFIED Walker, Berkley J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Mettler-Altmann, Tabea UNSPECIFIED UNSPECIFIED UNSPECIFIED Khoshravesh, Roxana UNSPECIFIED orcid.org/0000-0002-1766-8993 UNSPECIFIED Karki, Shanta UNSPECIFIED UNSPECIFIED UNSPECIFIED Bagunu, Efren UNSPECIFIED UNSPECIFIED UNSPECIFIED Sage, Tammy L. UNSPECIFIED UNSPECIFIED UNSPECIFIED Quick, W. Paul UNSPECIFIED UNSPECIFIED UNSPECIFIED Weber, Andreas P. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-592713
DOI:	10.1093/jxb/eraa343
Journal or Publication Title:	J. Exp. Bot.
Volume:	72
Number:	1
Page Range:	S. 137 - 153
Date:	2021
Publisher:	OXFORD UNIV PRESS
Place of Publication:	OXFORD
ISSN:	1460-2431
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language TEMPERATURE RESPONSE FUNCTIONS; PERIPHERAL RETICULUM; PLASTIDIC 2-OXOGLUTARATE/MALATE; C-4 PHOTOSYNTHESIS; CO2 ASSIMILATION; ENERGY-BALANCE; PHOTORESPIRATION; METABOLISM; EXPRESSION; LEAVES Multiple languages Plant Sciences Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/59271