Seed Oil Content and Fatty Acid Composition of Annual Halophyte Suaeda acuminata: A Comparative Study on Dimorphic Seeds

Seed heteromorphism is the phenomenon in which a single plant produces two or more seed types with different morphology and/or behavior. It is common in Asteraceae and Chenopodiaceae, and may be characterized by differences in seed size, dispersal, and dormancy and germination characteristics. Many studies have focused on the ecological differences between heteromorphic seeds and its offspring. However, few investigations were conducted to determine biochemical differences between heteromorphic seeds, and there is no study on fatty acid composition of heteromorphic seeds.

Suaeda acuminata is an annual halophyte restricted to central Asia. In China, S. acuminata is found only in the inland saline-alkaline deserts in Xinjiang. S. acuminata can produce two morphologically distinct types of seeds on the same plant: brown with soft coarse seed coat and black with rigid smooth seed coat.

In order to compare oil content and fatty acid composition of the two seed morphs, freshly matured seeds of S. acuminata S. acuminata were randomly collected from ca. 200 plants growing in an inland saline desert (87°46′10″E; 44°07′55″N; 500 m a.s.l). Seeds were cleaned and air-dried at　ambient temperature, and then separated by their color. Dry seeds were stored at room temperature until used.　The analysis result indicates that through oil characteristics between dimorphic seeds showed statistically sigificant difference, these differences were relatively small. The seed oil content of this species ranged from 14.3 to 15.5% by dry weight. Both seed morphs contain ca. 90% unsaturated fatty acids, with linoleic (>65%) and oleic acid (>14%) being the most abundant. The results show that oil reserve of S. acuminata seeds depends mainly on seed weight rather than seed morphology. The oil of S. acuminata seeds could be alternative source of high-quality edible oil due to the presence of high percent of polyunsaturated fatty acids required for human health. It is not necessary to separate seed morphs when producing oil because there is small difference in oil content and fatty acid composition between the two types of seeds.

This work was supported by the China Postdoctoral Science Foundation and the West Light Foundation of The Chinese Academy of Sciences. The main findings of this study have been published on African Journal of Biotechnology, 2011, 10(82): 19106-19108. This paper is also archived at http://academicjournals.org/AJB/full%20text/2011/19Dec/Wang%20et%20al.htm#Results_And_Disscussion.