Towards engineering increased pantothenate (vitamin B5) levels in plants

• DOI: 10.1007/s11103-008-9386-5
• Publication Date: 2008-08-22T11:10:05Z
• Authors: Ereck Chakauya; Katy M. Coxon; Ma Wei; Mary V. MacDonald; Tina Barsby; Chris Abell; Alison G. Smith
• Keywords: Hydroxymethyl and Formyl Transferases; 2. Zero hunger; 0303 health sciences; Brassica rapa; Fatty Acids; Flowers; Plants, Genetically Modified; Pantothenic Acid; Plant Leaves; 03 medical and health sciences; Phenotype; Gene Expression Regulation, Plant; Genes, Bacterial; Seedlings; Seeds; Escherichia coli; Genetic Engineering; Glucuronidase; Plasmids

Pantothenate (vitamin B(5)) is the precursor of the 4'-phosphopantetheine moiety of coenzyme A and acyl-carrier protein. It is made by plants and microorganisms de novo, but is a dietary requirement for animals. The pantothenate biosynthetic pathway is well-established in bacteria, comprising four enzymic reactions catalysed by ketopantoate hydroxymethyltransferase (KPHMT), L: -aspartate-alpha-decarboxylase (ADC), pantothenate synthetase (PS) and ketopantoate reductase (KPR) encoded by panB, panD, panC and panE genes, respectively. In higher plants, the genes encoding the first (KPHMT) and last (PS) enzymes have been identified and characterised in several plant species. Commercially, pantothenate is chemically synthesised and used in vitamin supplements, feed additives and cosmetics. Biotransformation is an attractive alternative production system that would circumvent the expensive procedures of separating racemic intermediates. We explored the possibility of manipulating pantothenate biosynthesis in plants. Transgenic oilseed rape (Brassica napus) lines were generated in which the E. coli KPHMT and PS genes were expressed under a strong constitutive CaMV35SS promoter. No significant change of pantothenate levels in PS transgenic lines was observed. In contrast plants expressing KPHMT had elevated pantothenate levels in leaves, flowers siliques and seed in the range of 1.5-2.5 fold increase compared to the wild type plant. Seeds contained the highest vitamin content, indicating that they might be the ideal target for production purposes.