Olive plant leaves

BIOSYNTHETIC PATHWAY OF Oc-LINOLENIC ACID IN OLIVE PLANT LEAVES... 

In the present study, we try to investigate the 18 3 synthesis in olive plant leaves ( 18 3 - plant) by labelling kinetics with sodium (l- C) acetate as precursor. 

Kinetics of (t- C) acetate incorporation into total fatty acids of olive plant leaves. 

One could believe that 18 1 was desaturated on DAG molecule before galacto-sylation and formation of DGG as it was proposed by KESRI-BEN HASSAINE(5) on Carthamus cotyledons, but the distribution of the radioactive precursor into DAG fatty acids in olive plant leaves (data not shown) indicated that only palmitic and oleic acids were labelled at any time of incubation. This lead us to think that the two desaturation steps of oleic acid could take place on DGG molecule (see the following scheme). However in the absence of a direct evidence this must remain merely as a hypothesis. 

Labelling experiments were carried out on young olive plant one year aged. Microdroplets of the radioactive solution (specific radioactivity 1,94GBq/ mmole) were deposited on the surface of the first leaf from the top. Leaves were harvested after different times of incubation (2,4,6,12,24 and 48 h) and rinsed with distilled water. Lipids were extracted in chloroform -methanol (1 2, v v) then separated by thin layer chromatography. The obtained fatty acids were analysed by radio gas chromatography. Details of the methods have been given elsewhere (6). 

Many works about the effect of saline environment on higher plants shown that salt stress affects several aspects of their physiological and biochemical functions (1,2,3). So, for the purpose of a better understanding of the olive tree physiology under saline conditions, we have studied the effects of calcium chloride on some glycerolipids metabolism aspects in olive tree leaf. 

Marzouk B., Zarrouk M. Cherif A. and Mazliak P. Calcium Chloride effect on glycerolipid metabolism in olive tree leaf. In "The Metabolism, Structure and Function of Plant Lipids", Stumpf P.K., Mudd J.B. and Nes W.D. Ed., USA, 1986, 317-319. 

Olive, M. R., Ellis, R. J., and Schuch, W. W. 1989. Isolation and nucleotide sequence of cDNA clones encoding ADPglucose pyrophosphorylase polypeptides from wheat leaf and endosperm. Plant Mol. Biol. 12, 525-538. 

Researchers interested in the properties and occurrence of natural antioxidants concentrate on vitamins E and C, carotenoids, phenolic acids, flavonoids, sesame lignins, phytosterols, extracts from the leaves of the plants belonging to the Lami-aceae family, oryzanols, tea leaf extracts, phosphatides, olive oil phenols, squalene, and propolis. Barrera-AreUano et al. (1999), Boskou (1999), Blekas and Boskou... 

Young olive tree plants two years aged were cultivated on sand and irrigated with nutrient solutions of variable concentrations 0, 5,5( 75 and 100 mM. Young leaves were incubated during 48 hours with Na acetate (36,4 mCi/mM) placed as microdroplets on the surface of the leaf. Lipid extraction and separation, radioactivity and methyl esters analysis have been described in a previous paper (4). 

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