Biochemical and physiological studies of Arabidopsis thaliana transgenic lines with repressed expression of the mitochondrial pyruvate dehydrogenase kinase

• Published in: Journal of experimental botany Vol. 54; no. 381; pp. 259 - 270
• Main Authors: Marillia, Elizabeth-France, Micallef, Barry J., Micallef, Malgre, Weninger, Alan, Pedersen, Kalie K., Zou, Jitao, Taylor, David C.
• Format: Journal Article
• Language: English
• Published: Oxford OXFORD UNIVERSITY PRESS 01.01.2003; Oxford University Press
• Subjects: Antisense Elements (Genetics) - genetics; Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis Proteins - genetics; Biological and medical sciences; Biosynthesis; Cloning, Molecular; Dehydrogenases; Fatty acids; Fatty Acids - biosynthesis; Fundamental and applied biological sciences. Psychology; Lipids; Metabolism; Metabolism. Physicochemical requirements; Mitochondria - enzymology; Molecular Sequence Data; Plant physiology and development; Plants; Plants, Genetically Modified; Pyruvate Dehydrogenase Complex - genetics; Pyruvate Dehydrogenase Complex - metabolism; Research Papers: Cell and Molecular Biology, Biochemistry and Molecular Physiology; Respiration; Seeds; Seeds - growth & development; Starches; Transgenic plants; Tubers; seed oil content; seed weight; Growth; mitochondrial pyruvate dehydrogenase complex; Resource allocation; Lipids; Biosynthesis; Metabolic pathway; Arabidopsis thaliana; Mitochondria; Regulation(control); Enzymatic activity; Triacylglycerol; Cruciferae; Dicotyledones; Angiospermae; Transgenic plant; Dihydrolipoamine S-acetyltransferase; Metabolic storage; Dihydrolipoamide dehydrogenase; Enzyme; Transferases; Pyruvate dehydrogenase (lipoamide); Plant leaf; Metabolism; [Pyruvate dehydrogenase (lipoamide)] kinase; plant development; Genetic improvement; Spermatophyta; pyruvate dehydrogenase kinase (EC 2.7.1.99); Oxidoreductases; Antisense DNA; Experimental plant; Respiration; early flowering
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/erg020

Pyruvate dehydrogenase kinase (PDHK), a negative regulator of the mitochondrial pyruvate dehydrogenase complex (mtPDC), plays a pivotal role in controlling mtPDC activity, and hence, the TCA cycle and cell respiration. Previously, the cloning of a PDHK cDNA from Arabidopsis thaliana and the effects of constitutively down-regulating its expression on plant growth and development has been reported. The first detailed analyses of the biochemical and physiological effects of partial silencing of the mtPDHK in A. thaliana using antisense constructs driven by both constitutive and seed-specific promoters are reported here. The studies revealed an increased level of respiration in leaves of the constitutive antisense PDHK transgenics; an increase in respiration was also found in developing seeds of the seed-specific antisense transgenics. Both constitutive and seed-specific partial silencing of the mtPDHK resulted in increased seed oil content and seed weight at maturity. Feeding 3-14C pyruvate to bolted stems containing siliques (constitutive transgenics), or to isolated siliques or immature seeds (seed-specific transgenics) confirmed a higher rate of incorporation of radiolabel into all seed lipid species, particularly triacylglycerols. Neither constitutive nor seed-specific partial silencing of PDHK negatively affected overall silique and seed development. Instead, oil and seed yield, and overall plant productivity were improved. These findings suggest that a partial reduction of the repression of the mtPDC by antisense PDHK expression can alter carbon flux and, in particular, the contribution of carbon moieties from pyruvate to fatty acid biosynthesis and storage lipid accumulation in developing seeds, implicating a role for mtPDC in fatty acid biosynthesis in seeds.