Studies of abscisic acid, cytokinins and gibberellins in maturing fruits of the oil palm (Elaeis Guineensis Jaquin)
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Date
1985
Authors
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Publisher
Obafemi Awolowo University, Ile Ife, Nigeria
Abstract
Maturing fruits of the oil palm (Elaeis guineensis JaCquin), were analysed for endogenous
abscisic acid, cytokinin and gibberellin activities in relation to the growth rates of such fruits.
Soybean callus bioassay was used to determine cytokinin activity both in n-butanol fractions,
paper chromatographed and developed in n-butanol: acetic acid: water solvent system and in
dried, 35% ethanol eluates from LH-20 Sephadex chromatographyl Lettuce hypocotyl and
lettuce germination bioassays were used to determine the respective activities of ethyl acetateand
n-butanol- soluble gibberellins and diethyl ether-soluble abscisic acid after subjecting both to
thin layer chromatography on silica gel. Developing solvent system for gibberellins was
isopropanol: water, while benzene: ethyl acetate: acetic acid was for abscisic acid.
The results of the bioassays showed that the hormone activities occurred mainly at Rf values of
0.1-0.2, 0.4.0.5 and 0.7-0,9 for cytokinins; 0.1-0.2; 0.3-0,5 and 0,6-0,8 for gibberellins and 0.4-
0.5 for abscisic acid. Co-chromatography with authentic growth substances gave Rf values at 0.7-
0.8 and 0.8-0.9 for zeatin and zeatin riboside respectively; 0.7-0.8 for gibberellic acid and 0.4-0.5
for abscisic acid.
The drupaceous oil palm fruits increase in growth with time and produced a sequence of
gibberellins, abscisic acid and cytokinins, each with four peaks of activity, the fluctuating level
of which could be linked to the accelerating, deceleration and asymptotic growth phases.
Endogenous gibberellic acid and abscisic acid were tentatively identified in this study. High
levels of free gibberellins occurred in the young fruits while the conjugated forms predominated
in the mature ones.
Four of the six isolated endogenous cytokinins were tentatively identified as zeatin, zeatin
riboside, isopentenyladenine and isopentenyladonosine. Although the interconversion between
ammonia- and water-soluble cytokinins presented an inconsistent pattern, yet the decrease in the
free cytokinins was concomitant with an increase in the conjugated forms in the water-soluble
fractions during fruit maturation.
Description
158p
Keywords
Abscisic, Cytokinin, Gibberellin, Oil, palm, Chromatography, Fruit