title: Seed-specific expression of a bacterial phosphoenolpyruvate carboxylase in Vicia narbonensis increases protein content and improves carbon economy.
abstract: An ambitious aim in plant breeding and biotechnology is to increase the protein content of crop seeds used for food and feed. Using an approach to manipulate assimilate partitioning, we succeeded in elevating the protein content in legume seeds up to 50%. Transgenic bean plants were generated which express a Corynebacterium glutamicum phosphoenolpyruvate carboxylase (PEPC) in a seed-specific manner. The bacterial enzyme was not feedback inhibited by malate. Transgenic seeds showed a higher [14C]-CO2 uptake and about a threefold increased incorporation of labelled carbon into proteins. Changed metabolite profiles of maturing cotyledons indicated a shift of metabolic fluxes from sugars/starch into organic acids and free amino acids. These changes were consistent with an increased carbon flow through the anaplerotic pathway catalysed by PEPC. Consequently, transgenic seeds accumulated up to 20% more protein per gram seed dry weight. Additionally, seed dry weight was higher by 20%-30%. We conclude that PEPC in seeds is a promising target for molecular plant breeding.
authors.affiliation: Institut für Pflanzengenetik und Kulturpflanzenforschung, D-06466 Gatersleben, Germany.
authors.forename: Hardy
authors.initials: H
authors.lastname: Rolletschek
authors.forename: Ljudmilla
authors.initials: L
authors.lastname: Borisjuk
authors.forename: Ruslana
authors.initials: R
authors.lastname: Radchuk
authors.forename: Manoela
authors.initials: M
authors.lastname: Miranda
authors.forename: Ute
authors.initials: U
authors.lastname: Heim
authors.forename: Ulrich
authors.initials: U
authors.lastname: Wobus
authors.forename: Hans
authors.initials: H
authors.lastname: Weber