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Suppression of NDA-type alternative mitochondrial NAD(P)H dehydrogenases in Arabidopsis thaliana modifies growth and metabolism, but not high light stimulation of mitochondrial electron transport.

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Author

  • Sabá Wallström
  • Igor Florez-Sarasa
  • Wagner L Araújo
  • Matthew A Escobar
  • Daniela A Geisler
  • Mari Aidemark
  • Ida Lager
  • Alisdair R Fernie
  • Miquel Ribas-Carbó
  • Allan G. Rasmusson

Summary, in English

The plant respiratory chain contains several pathways which bypass the energy-conserving electron transport complexes I, III, and IV. These energy-bypasses, including type II NAD(P)H dehydrogenases and the alternative oxidase (AOX), may have a role in redox-stabilisation and regulation, but current evidence is inconclusive. Using RNA interference, we generated Arabidopsis thaliana plants simultaneously suppressing the type II NAD(P)H dehydrogenase genes NDA1 and NDA2. Leaf mitochondria contained substantially reduced levels of both proteins. In sterile culture in the light, the transgenic lines displayed a slow growth phenotype, which was more severe when the complex I inhibitor rotenone was present. Slower growth was also observed in soil. In rosette leaves, a higher NAD(P)H/NAD(P)(+)-ratio and elevated levels of lactate relative to sugars and citric acid cycle metabolites were observed. However, photosynthetic performance was unaffected and microarray analyses indicated few transcriptional changes. A high light treatment increased AOX1a mRNA levels, in vivo AOX and cytochrome oxidase activities, and levels of citric acid cycle intermediates and hexoses in all genotypes. However, NDA-suppressing plants deviated from the wild type merely by having higher levels of several amino acids. These results suggest that NDA-suppression restricts citric acid cycle reactions, inducing a shift towards increased levels of fermentation products, but do not support a direct association between photosynthesis and NDA proteins.

Publishing year

2014

Language

English

Pages

881-896

Publication/Series

Plant and Cell Physiology

Volume

55

Issue

5

Document type

Journal article

Publisher

Oxford University Press

Topic

  • Biological Sciences

Status

Published

Research group

  • Plant Biology

ISBN/ISSN/Other

  • ISSN: 1471-9053