Comparative study of storage compound breakdown in germinating seeds of three lupine species

Storage lipid and protein breakdown in germinating seeds of yellow ( Lupinus luteus L.), white ( L. albus L.), and Andean lupine ( L. mutabilis Sweet) and regulatory function of sucrose were investigated. Less oil bodies were detected in organs of yellow lupine seeds, whereas the highest content of oil bodies was noticed in the Andean lupine seeds. Mature, air-dried yellow, white and Andean lupine seeds do not contain starch. Starch grains appear the earliest in white lupine seeds during imbibition. Sucrose deficiency in tissues enhances breakdown of storage lipid, protein and temporary starch in cotyledons. In sucrose starved embryo axes of all investigated lupine species, an increased level of vacuolization was noted. Interconnections between catabolism of storage protein and storage lipid in germinating lupine seeds were identified by applying 14 C-acetate. To assess the importance of key processes in storage lipid breakdown NaF (inhibitor of glycolysis and gluconeogenesis), KCN, NaN 3 and SHAM (inhibitors of mitochondrial electron transport chain) and MSO (inhibitor of glutamine synthetase) were used. Radioactivity coming from 14 C-acetate was released as 14 CO 2 but mostly was incorporated into ethanol-soluble fraction of embryo axes and cotyledons. Respiratory inhibitors caused a significant decrease in 14 CO 2 and ethanol fractions in all three lupine species studied. MSO stimulated release of 14 CO 2 and radioactivity of ethanol fractions in yellow lupine organs fed with sucrose, but in Andean lupine MSO enhanced the production of 14 CO 2 and radioactivity of ethanol fractions both in organs fed and not fed with sucrose. Different strategies of storage compound breakdown are proposed, depending on relative proportion in storage protein and lipid content in lupine seeds.