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.
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 stabilization 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.
Department of Biology, Lund University, Biology building A, Sölvegatan 35, SE-22362 Lund, Sweden.
Sabá V
SV
Wallström
Igor
I
Florez-Sarasa
Wagner L
WL
Araújo
Matthew A
MA
Escobar
Daniela A
DA
Geisler
Mari
M
Aidemark
Ida
I
Lager
Alisdair R
AR
Fernie
Miquel
M
Ribas-Carbó
Allan G
AG
Rasmusson
D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D015153:Blotting, Western; D002952:Citric Acid Cycle / Q000187:drug effects / Q000528:radiation effects; D004579:Electron Transport / Q000187:drug effects / Q000528:radiation effects; D038181:FMN Reductase / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008027:Light; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D024101:Mitochondrial Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012402:Rotenone / Q000494:pharmacology; D012689:Sequence Homology, Nucleic Acid; D046509:Tissue Culture Techniques; D059467:Transcriptome / Q000187:drug effects / Q000528:radiation effects; D014475:Uncoupling Agents / Q000494:pharmacology; D000099188:Alternative Oxidase
D029681:Arabidopsis Proteins; D038181:FMN Reductase; D007527:Isoenzymes; D024101:Mitochondrial Proteins; D009247:NADH, NADPH Oxidoreductases; D010088:Oxidoreductases; D010940:Plant Proteins; D012402:Rotenone; D014475:Uncoupling Agents; D000099188:Alternative Oxidase; C000595146:NDA1 protein, Arabidopsis; C000595147:NDA2 protein, Arabidopsis
Alternative electron transport; Citric acid cycle; Fermentation; Mitochondria; NAD(P)H dehydrogenase; RNA interference