The occurrence of abscisic acid in inhibitors B1 and C from immature fruit of Ceratonia siliqua L. (carob) and in commercial carob syrup

Identification and measurement of indoleacetic and abscisic acids in the cambial region of Picea sitchensis (Bong.) Carr. by combined gas chromatography-mass spectrometry

Indole-3-acetic acid (IAA) and abscisic acid (ABA) were identified by combined gas chromatography-mass spectrometry (GCMS) in fractions obtained by diffusion and extraction from bark peelings of Sitka spruce. A procedure is described for the quantitative analysis of IAA and ABA levels in the same extract using the GCMS technique of single-ion current monitoring. This procedure was used to measure the diffusible, free, and bound fractions of IAA and ABA in the cambial region of Sitka spruce throughout one year; the range in concentration for these fractions was 0.06-0.30, 0.46-3.85, and 0.04-0.20 μg/g oven-dry weight, respectively, for IAA, and 0-0.08, 0.03-2.21, and 0.13-0.66 μg/g oven-dry weight, respectively, for ABA. Movement in the cambial region was found to be polar for endogenous IAA and nonpolar for endogenous ABA. Recoveries of [(14)C]IAA internal standards showed that 73-99.5% of the IAA was lost during purification, and that there could be up to 5-fold differences in recovery between purifications, indicating that IAA loss shold be measured in quantitative analyses.

Abscisic acid as an endogenous component in lettuce fruits, Lactuca sativa L. cv. Grand Rapids. Does it control thermodormancy?

Abscisic acid (ABA) has been unequivocally identified as an endogenous component of seeds of Grand Rapids lettuce. Both "free" and "bound" ABA levels were followed during imbibition at various temperatures but no clear role for ABA in the imposition of thermodormancy emerged. Furthermore it was apparent that different seed batches showed different ratios of "free" to "bound" ABA and patterns of changes. An unsuccessful attempt was made to identify "bound" ABA, presumed to be the glucosyl ester.

Studies in the Turkish Carob (Ceratonia siliqua L.) : IV. Acidic auxin-like and inhibitory substances in fruit morphogenesis

Ceratonia siliqua L. exhibited a sigmoid growth pattern with each stage being controlled by specific substances. At least three auxin-like substances were involved during fruit morphogenesis with the main one being at indole-acetic acid Rf. Auxin-like substances were present at highest level during stage II, when fruit showed active growth, but decreased at the arrival of stage III. The inhibiting substance I1, at abscissic acid Rf, was present at the highest level at this stage. However, I2, detected towards the last stages of development, was not present at a significant level. The results obtained have been discussed in detail.

Studies in seed dormancy : VII. The abscisic acid content of the seeds and fruits of Corylus avellana L

ABA has been identified by GLC-MS and routinely determined by GLC as one of several inhibitory substances in the testa and pericarp of hazel nuts. Its concentration in newly harvested nuts, which had not developed embryo dormancy, was 19.0 nmoles/g dry weight for the testa, 1.4 nmoles/g for the pericarp and 0.09 nmoles/g for the embryo. Dry storage of the nuts resulted in the development of embryo dormancy together with a slight loss of ABA. On imbibition of dormant nuts at 5° C and 20° C there was a 61% loss of ABA from the testa and pericarp in both cases. However the 5° C imbibition resulted in the breaking of seed dormancy while the 20° C imbibition had no effect on the dormancy. The ABA of the testa and pericarp seems to be concerned with the maintenance of seed dormancy prior to the onset of embryo dormancy. Subsequent to the onset of embryo dormancy, ABA seems to show little effect on either the maintenance or breaking of seed dormancy.

Identification of gibberellin A20, abscisic acid, and phaseic acid from flowering Bryophyllum daigremontianum by combined gas chromatography-mass spectrometry

The presence of abscisic and phaseic acid in a purified acidic extract from flowering plants of the long-short-day plant Bryophyllum daigremontianum [(R. Hamet and Perr.) Berg.] was conclusively established by combined gas chromatography-mass spectrometry (GC-MS) of their methyl esters. Gibberellin A20 (GA20) was identified by GC-MS of the methyl ester and the trimethylsilyl ether of the methyl ester. The following levels of the 3 compounds per kg fresh weight were estimated: Abscisic acid, 5.5 μg; phaseic acid, 9.4μg; gibberellin A20, 0.8 μg. When GA20 and four other GAs were applied to Bryophyllum under shortday conditions, the order of effectiveness for induction of flower formation was: GA2>GA1>GA5=GA7>GA20. The low biological activity of the native GA20 is discussed.

Endogenous abscisic acid in relation to photoperiodically induced bud dormancy

The abscisic acid contents of birch, maple and sycamore plants growing under long and short photoperiods were measured by gas-liquid chromatography. No increase was observed in the abscisic acid content of extracts when plants were transferred to dormancy-inducing conditions.

Inhibitors from carob (Ceratonia siliqua L.) : III. Comparisons with abscisic acid

Inhibitory extracts of carob and abscisic acid (ABA) were compared and found to behave differently in three types of tests. The carob inhibitors remained at the origin upon thin-layer chromatography in two different solvent systems while a cis-trans mixture of ABA had Rf's of 2.5 and 3.5 in the first system (chloroform:acetic acid, 95:5), and 3.5 and 4.5 in the second system (benzene:acetic acid:water, 8:3:5). When ABA and carob extract were mixed and then chromatographed, the ABA had the same Rf values as ABA chromatographed alone.Assays utilizing light-grown, dwarf peas showed that a weight ratio of 1000: 1 ABA:gibberellic acid (GA3) was necessary to inhibit GA3-induced growth by 50% while carob fraction C is inhibitory to GA3 at a ratio of 17:1. The amount of ABA which inhibited 50% of the growth induced by 0.05 μg GA3 reduced the endogenous growth of both dwarf and non-dwarf pea seedlings; in contrast, concentrations of carob extract up to 100 times greater than the amount necessary for 50% inhibition of the growth response caused by 0.05 μg GA3 did not affect endogenous growth.Only very small amounts of inhibitory activity from carob extract were transferred from water to chloroform at a pH (2.0) at which most of the ABA was transferred.