Synthesis of storage reserves in developing seeds of sunflower

Abstract A combination of biochemical analyses and Northern blotting were used to determine the patterns of storage reserve (oil, 2S albumin, helianthinin, oleosin) synthesis during the early stages of embryo development in sunflower. This demonstrated that oleosin biosynthesis is initiated early in development which is consistent with a role in oil body biogenesis. The patterns of synthesis and accumulation of storage compounds were compared in young developing embryos of sunflower. Oil biosynthesis was clearly initiated very early in development with total lipids accounting for about 18% of the dry weight at the earliest stage studied. This was associated with the accumulation of oleosins and the expression of cytochrome b 5 . In contrast, significant amounts of helianthinin (11S globulin) and 2S albumin were only observed in stages 3 and 4, respectively. The early expression of oleosins contrasts with previous studies of other oilseeds and is consistent with the hypothesis that they are intimately associated with the biogenesis of oil bodies.