Antisense Knockdown Of Pyruvate Dehydrogenase Kinase Promotes The Neutral Lipid Accumulation In Diatom Phaeodactylum Tricornutum

Microalgae are considered the new important source of biodiesel.Diatoms are important primary producers in the marine ecosystem,genetic engineering of diatom has been slow compared to higher plants due to existing technical limitations.Pyruvate dehydrogenase kinase(PDK)inactivates the multimeric mitochondrial pyruvate dehydrogenase complex(PDC)which catalyzes the oxidative decarboxylation of pyruvate.Acetyl-Co A production via PDC is important in plant tissues that are active in fatty acid synthesis.In this study,a 1261-bp c DNA fragment of a putative PDK gene(Pt PDK1)was cloned from a model diatom Phaeodactylum tricornutum.A construct containing antisense Pt PDK1 c DNA driven by promoter/terminator of fcp C gene was obtained.CAT(chloramphenicol acetyltransferase)driven by the nitrate reductase promoter/terminator from the diatom was used as selection marker for genetic transformation.The construct was transferred by electroporation into P.tricornutum grown in medium minus silicon.Expression of CAT in transformed diatom induced resistance to chloramphenicol and enabled growth in selective medium.The Pt PDK1 expression was knocked down significantly detected by western blot analysis.Fatty acid content of transgenic diatom increased up to 30%.This work first obtained a successful transgenic diatom regulating a key gene involved in lipid metabolism in diatoms.Our findings also provide indications of constitutive regulated approach to enhancing microalgal lipid production for biofuel.