Molecular Plant
Volume 7, Issue 2, February 2014, Pages 356-368
Journal home page for Molecular Plant

Research Article
Suppression of the External Mitochondrial NADPH Dehydrogenase, NDB1, in Arabidopsis thaliana Affects Central Metabolism and Vegetative Growth

https://doi.org/10.1093/mp/sst115Get rights and content
Under an Elsevier user license
open archive

ABSTRACT

Ca2+-dependent oxidation of cytosolic NADPH is mediated by NDB1, which is an external type II NADPH dehydrogenase in the plant mitochondrial electron transport chain. Using RNA interference, the NDB1 transcript was suppressed by 80% in Arabidopsis thaliana plants, and external Ca2+-dependent NADPH dehydrogenase activity became undetectable in isolated mitochondria. This was linked to a decreased level of NADP+ in rosettes of the transgenic lines. Sterile-grown transgenic seedlings displayed decreased growth specifically on glucose, and respiratory metabolism of 14C-glucose was increased. On soil, NDB1-suppressing plants had a decreased vegetative biomass, but leaf maximum quantum efficiency of photosystem II and CO2 assimilation rates, as well as total respiration, were similar to the wild-type. The in vivo alternative oxidase activity and capacity were also similar in all genotypes. Metabolic profiling revealed decreased levels of sugars, citric acid cycle intermediates, and amino acids in the transgenic lines. The NDB1-suppression induced transcriptomic changes associated with protein synthesis and glucosinolate and jasmonate metabolism. The transcriptomic changes also overlapped with changes observed in a mutant lacking ABAINSENSITIVE4 and in A. thaliana overexpressing stress tolerance genes from rice. The results thus indicate that A. thaliana NDB1 modulates NADP(H) reduction levels, which in turn affect central metabolism and growth, and interact with defense signaling.

SUMMARY

The external mitochondrial NADPH dehydrogenase in Arabidopsis is shown to modify the cellular NADP(H) reduction level. This is in turn associated with a modified citric acid cycle, sugar metabolism, and growth, as well as changes in stress defense-associated gene expression.

Key words

citric acid cycle
metabolic profiling
mitochondrial respiration
NADPH
RNA interference
type II NAD(P)H dehydrogenase
vegetative growth

Cited by (0)

Published by the Molecular Plant Shanghai Editorial Office in association with Oxford University Press on behalf of CSPB and IPPE, SIBS, CAS.