title: Evidence of a key role for photosynthetic oxygen release in oil storage in developing soybean seeds.
abstract: Based on the topographical analysis of photosynthesis and oil storage, we propose in a companion paper that photosynthetic oxygen release plays a key role in the local energy state, storage metabolism and flux toward lipid biosynthesis in developing soybean seeds. To test this hypothesis, we combined topographical analysis of ATP gradients across tissues, microsensor quantifications of internal O2 levels, assays of energy balance, metabolite profiles and isotope-labelling studies. Seeds show a marked degree of oxygen starvation in vivo (minimum O2 levels 0.1 kPa, approximately 1.3 microm), affecting ATP gradients, overall energy state, metabolite pools and storage activity. Despite the low light availability, photosynthesis supplies significant amounts of oxygen to the hypoxic seed tissue. This is followed by an increase in local ATP levels, most prominently within the lipid-synthesizing (inner) regions of the embryo. Concomitantly, partitioning of 14C-sucrose to lipids is increased, suggesting higher rates of lipid biosynthesis. It is concluded that both respiratory and biosynthetic fluxes are dynamically adjusted to photosynthetic oxygen supply.
authors.affiliation: Institut für Pflanzengenetik und Kulturpflanzenforschung, Corrensstr. 3, 06466 Gatersleben, Germany.
authors.forename: Hardy
authors.initials: H
authors.lastname: Rolletschek
authors.forename: Ruslana
authors.initials: R
authors.lastname: Radchuk
authors.forename: Christian
authors.initials: C
authors.lastname: Klukas
authors.forename: Falk
authors.initials: F
authors.lastname: Schreiber
authors.forename: Ulrich
authors.initials: U
authors.lastname: Wobus
authors.forename: Ljudmilla
authors.initials: L
authors.lastname: Borisjuk
mesh_terms: D000255:Adenosine Triphosphate; D000596:Amino Acids / Q000378:metabolism; D050260:Carbohydrate Metabolism; D008027:Light; D050356:Lipid Metabolism; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D010788:Photosynthesis / Q000502:physiology*; D012639:Seeds / Q000254:growth & development* / Q000378:metabolism*; D013025:Glycine max / Q000196:embryology*
chemical_list: D000596:Amino Acids; D000255:Adenosine Triphosphate; D010100:Oxygen