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amino acid metabolism, ETF/ETFQO pathway, carbon partition, germination, primary metabolism, seed development
Abstract:
Abstract The importance of the alternative donation of electrons to the ubiquinol pool via the electron-transfer flavoprotein/electron-transfer flavoprotein:ubiquinone oxidoreductase (ETF/ETFQO) complex has been demonstrated. However, the functional significance of this pathway during seed development and germination remains to be elucidate. To assess the function of this pathway, we performed a detailed metabolic and transcription analyzes of Arabidopsis mutants to test the molecular consequences of a dysfunctional ETF/ETFQO pathway. We demonstrate that the disruption of this pathway compromises seed germination in the absence of an external Carbon-source and also impacts seed size and yield. Total protein and storage proteins content is reduced in dry seeds, whilst sucrose levels remain invariant. Seeds of ETFQO and related mutants were also characterized by an altered fatty acid composition. During seed development, lower levels of fatty acids and proteins accumulated in the etfqo-1 mutant as well as in the alternative electron donors, isovaleryl-CoA dehydrogenase (ivdh-1) and D-2-hydroxyglutarate dehydrogenase (d2hgdh1-2) mutant. Furthermore, the content of several amino acids was increased in etfqo-1 mutants during seed development, indicating that these mutants are not using such amino acids as alternative energy source for respiration. Transcriptome analysis revealed alterations in several genes involved in energy and hormonal metabolism. Our findings demonstrated that the alternative pathway of respiration mediated by the ETF/ETFQO complex affects seed germination and development by direct adjusting C storage during seed filling. These results provide a role for the pathway in the normal plant life cycle to complement its previously defined roles in response to abiotic stress.
