Ultrastructural changes in oil bodies accumulation and fatty acids composition during seed development of styrax tonkinensis

Styrax tonkinensis is a potential biofuel feedstock due to having high seed oil content and excellent fatty acid composition. This study aims at oil bodies formulation and fatty acids composition of the oil extracts from S. tonkinensis seeds. Oil bodies acquired through transmission electron microscopy (TEM) at 40 days after flowering (DAF), but the peak of oil bodies was observed after 100 DAF. Then, the size of the oil bodies generally increased, while their number decreased. The highest crude oil content (68%, w/w of dry seed) was recorded in seeds harvested in early October. The time-dependent process of oil accumulation during seed development showed a two-phase framework, with a high rate of increase of oil content during 20-40 and 80-100 DAF. GC/MS analysis showed that the main fatty acids (FAs) were linoleic acid, oleic acid, palmitic acid and stearic acid and their contents were 44.31-63.59%, 37.1-43.65%, 6.92-20.89% and 1.73-8.13%, respectively. And the ratio of unsaturated/saturated fatty acids was affected by climatic temperature significantly. This revealed that the ultrastructure of the endosperm and embryo significantly changed with the accumulation process of the oil bodies and fatty acids composition during the development of S. tonkinensis seeds.