ULTRASTRUCTURAL AND CHEMICAL STUDIES AN SEEDS OF BULNESIA-SCHICKENDANTZII AND BULNESIA-BONARIENSIS

Bulnesia, a genus of the Zygophyllaceae, comprises two subgenera, subg enus Bulnesia and subgenus Gonopterodendron. One species of each subge nus was studied: B. schickendantzii and B. bonariensis, respectively. B. schickendantzii endosperm consists of four to six cell layers. Cell walls are composed of a middle lamella, a very thick outer wail and a thin inner wall. B. bonariensis endosperm is reduced to one layer of cells. The cell walls are formed by a middle lamella and a thinner wal l. Protein bodies are observed in the embryo of both species and in th e endosperm of B. schickendantzii. Lipid vesicles are present in the e mbryo and endosperm of both species. Phytin crystals, present in the p rotein bodies of B. schickendantzii, are rare in the protein bodies of B. bonariensis. B. schickendantzii endosperm contains the majority of sugars and proteins. In B. bonariensis the higher percentage of carbo hydrate and protein is found in the embryo. Determination of neutral s ugars was performed after acid hydrolysis. Sugars were analysed as ald itol acetates by gas-liquid chromatography. Arabinose, xylose, galacto se and glucose are the main monosaccharides but the ratio differs in t issues of both species. Soluble proteins were analysed by polyacrylami de gel electrophoresis, showing a different profile in tissues of both species. Very few bands are glycosylated. The ultrastructural and che mical differences observed between both species suggest the segregatio n of Gonopterodendron from the genus Bulnesia as a separate genus and encourage further studies of the other six species in order to confirm this assertion.