Universität zu Köln

Levey, Myles, Timm, Stefan ORCID: 0000-0003-3105-6296, Mettler-Altmann, Tabea, Borghi, Gian Luca ORCID: 0000-0002-6933-2615, Koczor, Maria, Arrivault, Stephanie, Weber, Andreas P. M., Bauwe, Hermann ORCID: 0000-0001-7802-8925, Gowik, Udo ORCID: 0000-0002-8986-7318 and Westhoff, Peter (2019). Efficient 2-phosphoglycolate degradation is required to maintain carbon assimilation and allocation in the C-4 plant Flaveria bidentis. J. Exp. Bot., 70 (2). S. 575 - 588. OXFORD: OXFORD UNIV PRESS. ISSN 1460-2431

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Abstract

Photorespiration is indispensable for oxygenic photosynthesis since it detoxifies and recycles 2-phosphoglycolate (2PG), which is the primary oxygenation product of Rubisco. However, C-4 plant species typically display very low rates of photorespiration due to their efficient biochemical carbon-concentrating mechanism. Thus, the broader relevance of photorespiration in these organisms remains unclear. In this study, we assessed the importance of a functional photorespiratory pathway in the C-4 plant Flaveria bidentis using knockdown of the first enzymatic step, namely 2PG phosphatase (PGLP). The isolated RNAi lines showed strongly reduced amounts of PGLP protein, but distinct signs of the photorespiratory phenotype only emerged below 5% residual PGLP protein. Lines with this characteristic were stunted in growth, had strongly increased 2PG content, exhibited accelerated leaf senescence, and accumulated high amounts of branched-chain and aromatic amino acids, which are both characteristics of incipient carbon starvation. Oxygen-dependent gas-exchange measurements consistently suggested the cumulative impairment of ribulose-1,5-bisphosphate regeneration with increased photorespiratory pressure. Our results indicate that photorespiration is essential for maintaining high rates of C-4 photosynthesis by preventing the 2PG-mediated inhibition of carbon utilization efficiency. However, considerably higher 2PG accumulation can be tolerated compared to equivalent lines of C-3 plants due to the differential distribution of specific enzymatic steps between the mesophyll and bundle sheath cells.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Levey, Myles UNSPECIFIED UNSPECIFIED UNSPECIFIED Timm, Stefan UNSPECIFIED orcid.org/0000-0003-3105-6296 UNSPECIFIED Mettler-Altmann, Tabea UNSPECIFIED UNSPECIFIED UNSPECIFIED Borghi, Gian Luca UNSPECIFIED orcid.org/0000-0002-6933-2615 UNSPECIFIED Koczor, Maria UNSPECIFIED UNSPECIFIED UNSPECIFIED Arrivault, Stephanie UNSPECIFIED UNSPECIFIED UNSPECIFIED Weber, Andreas P. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bauwe, Hermann UNSPECIFIED orcid.org/0000-0001-7802-8925 UNSPECIFIED Gowik, Udo UNSPECIFIED orcid.org/0000-0002-8986-7318 UNSPECIFIED Westhoff, Peter UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-159141
DOI:	10.1093/jxb/ery370
Journal or Publication Title:	J. Exp. Bot.
Volume:	70
Number:	2
Page Range:	S. 575 - 588
Date:	2019
Publisher:	OXFORD UNIV PRESS
Place of Publication:	OXFORD
ISSN:	1460-2431
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language PHOTORESPIRATORY MUTANTS; OXYGEN SENSITIVITY; GLYCOLATE OXIDASE; PHOTOSYNTHESIS; EVOLUTION; CYANOBACTERIA; METABOLISM; GENE; POLYACRYLAMIDE; TRANSFORMATION Multiple languages Plant Sciences Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/15914