Abscisic Acid Levels and Seed Dormancy

Sondheimer, Ernest; Tzou, D. S.; Galson, Eva C.

doi:10.1104/pp.43.9.1443

Cited by 92 publications

(32 citation statements)

References 11 publications

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“…A number of trends become apparent, particularly if the content of glucosides is compared before and after germination. When dormant embryos are incubated for 10 days, there is little germination, the fresh weight increase is low, and the concentration of the three glucosides does not change significantly from that of freshly excised dormant embryos.…”

Section: Resultsmentioning

confidence: 95%

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Metabolically Active Glucosides in Oleaceae Seeds

et al. 1970

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The seeds of six woody species of Oleaceae representing three genera, contain high concentrations of water-soluble glucosides, with major absorption maxima below 240 nanometers. In Fraxinus americana seeds three of these compounds, designated GL-3, GL-5, and GL-6, account for almost 10% of the dry weight. They are found in the endosperm and embryo but not in the pericarp. While the level of GL-5 is not particularly influenced by the physiological state of the embryo, that of GL-3 and GL-6 decreases as a result of germination and growth during a 10-day period. As the concentrations of GL-3 and GL-6 decrease, new ultraviolet-absorbing compounds are formed. The changes in the concentration of the ultraviolet-absorbing glucosides during cold temperature after-ripening, prior to germination, are small. When germination of dormant embryos is induced with gibberellic acid, the concentrations of GL-3 and GL-6 decrease in a manner similar to that observed with nondormant embryos. In the presence of abscisic acid no losses of GL-3 and GL-6 were observed. It is suggested that GL-3 and GL-6 fulfill some definite functions in the germination and growth of F. americana embryos, and that gibberellic acid and abscisic acid can exert a regulatory effect on the metabolism of these glucosides.The germination of white ash seeds, Fraxinus americana, normally requires the breaking of dormancy through cold temperature after-ripening. Embryos excised from dormant seeds will not germinate at 22 C under the same conditions that permit germination of embryos from nondormant seeds. Gibberellins and cytokinins allow germination and growth of dormant embryos while ABA' prevents these processes (9). The endogenous levels of the latter hormone reflect the physiological states of the embryos, lower levels being found in nondormant seeds (10).To gain insight into the mode of actions of these hormones, the changes in certain storage nutrients during germination of F. americana seeds were followed, and the effects of exogenously added GA3 and ABA were determined. Attention was focused on carbohydrates since evidence is accumulating that at least one role of GA3 in germination and development of many seeds involves the breakdown of starch (1, 5).Examination of dry F. americana seeds showed that while they are free of starch they do contain high concentrations of water-1 Abbreviations: ABA: abscisic acid; TLC: thin layer chromatography.soluble, ultraviolet-absorbing, dialyzable glucosides. Three of these glucosides, designated GL-3, GL-5, and GL-6-to indicate that they are glucosides and can be distinguished by their R, values-have been purified sufficiently to permit structural work. The quantitative determination of the glucosides is based on their intense absorption near 240 nm and purification by TLC. This method has been used to determine the distribution of GL-3, GL-5, and GL-6 in six species, representing three genera of the Oleacea family. Changes in concentration of the glucosides in F. americana seeds as a function of cold temperat...

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Section: Resultsmentioning

confidence: 95%

“…Gibberellins and cytokinins allow germination and growth of dormant embryos while ABA' prevents these processes (9). The endogenous levels of the latter hormone reflect the physiological states of the embryos, lower levels being found in nondormant seeds (10).…”

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Metabolically Active Glucosides in Oleaceae Seeds

et al. 1970

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“…The concentration of ABA in the seeds and pericarp of F. americana has been shown to decrease during the course of stratification to approximately that found in the nondormant F. ornus (6). These latter results suggested the possibility of ABA metabolism during the stratification process.…”

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confidence: 79%

“…From our data one can calculate that the dormant embryos have the capacity to metabolize ABA at the rate of at least 10 ,ug/g fresh weight*day. This compares with an ABA level in dormant seed of approximately 0.2 ,ug/g fresh weight (6).…”

Section: Discussionmentioning

confidence: 99%

The Metabolism of Hormones during Seed Germination and Dormancy

Sondheimer¹,

Galson²,

Tinelli³

et al. 1974

Plant Physiol.

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Embryos from dormant and stratified Fraxinus americana seed were incubated with (S)-2-"C-abscisic acid (ABA) under a variety of conditions. Both dormant and stratified embryos rapidly metabolize abscisic acid to phaseic acid, dihydrophaseic acid, and an unidentified polar metabolite apparently derived from dihydrophaseic acid. Although the stratified embryos may have an increased capacity to metabolize abscisic acid, our calculations suggest that such an increased capacity would probably not be physiologically significant. Dormant intact seeds also metabolize (S)-2-VC-abscisic acid during stratification at 5 C or incubation at 25 C. The metabolites appear to be similar to those observed in excised embryos although by 12 days of stratification a fourth metabolite is observed. More than 90% of the "C-abscisic acid was metabolized after 26 days of stratification at 5 C or after 12 days of incubation at 25 C. Stratification at 5 C leads to the breaking of dormancy while incubation at 25 C does not.The plant growth regulator ABA prevents germination when applied to embryos of Fraxinus ornus, a nondormant ash species, and to F. americana embryos from seeds whose dormancy has been overcome by stratification (5). The concentration of ABA in the seeds and pericarp of F. americana has been shown to decrease during the course of stratification to approximately that found in the nondormant F. ornus (6). These latter results suggested the possibility of ABA metabolism during the stratification process. While ABA has been shown to be metabolized rapidly in several other plants including tomato and bean (4, 11), its metabolism in dormant tissues has not been reported. We were interested in the extent to which ABA is metabolized by dormant seeds, the identity of the metabolites and in the possibility that the stratification process might result in an increased capacity for ABA metabolism. In order to answer these 'Eva Galson, Eugene Tinelli, and Daniel Walton dedicate this paper to the memory of our colleague and friend, Ernest Sondheimer. We shall sadly miss his companionship, creativity, and infectious enthusiasm for research.questions about ABA metabolism, dormant and stratified excised F. americana embryos and endosperm were incubated with 2-"`C-ABA. 2-w"C-ABA metabolism was also followed in intact seeds during a stratification period at 5 C sufficient to break dormancy, and during an incubation period at 25 C which does not result in the breaking of domancy. All of this work was done with the naturally occurring (S) enantiomer of ABA, and in some cases with the (R) enantiomer also. Relatively large scale incubations of embryos with (RS)-2-uC-ABA were also done in order to obtain sufficient quantities of metabolites for identification by chemical and spectral methods.MATERIALS AND METHODS Short Term Incubations. F. americana seeds (1971 crop from Herbst Bros., Brewster, N.Y.) were depericarped by hand and then imbibed in tap water for 24 hr. After the embryos were excised, they were shaken for 24 hr in 25-ml round b...

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“…It has been implicated in such plant growth processes as senescense, ab scission of leaves, flowers, and fruits: rest and dormancy of seeds, buds, and tubers; and inhibition of vegetative growth (Sondheimer et al, 1968;Addicott and Lyon, 1969). Addicott and Lyon (1969) showed that exogenous application of ABA can in hibit stem and bud growth.…”

Section: Auxins Have Been Implicated As Inhibitory Factors In Apical mentioning

confidence: 99%

The effect of hormones and chemical growth regulators on ear development and grain yield of nonprolific corn (Zea mays L.)

Khosravi

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Abscisic Acid Levels and Seed Dormancy

Cited by 92 publications

References 11 publications

Metabolically Active Glucosides in Oleaceae Seeds

Metabolically Active Glucosides in Oleaceae Seeds

The Metabolism of Hormones during Seed Germination and Dormancy

The effect of hormones and chemical growth regulators on ear development and grain yield of nonprolific corn (Zea mays L.)

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