Identification of Endogenous Gibberellins in Dormant Bulbils of Chinese Yam, Dioscorea opposita

It is known that dormancy of the genus Dioscorea is induced by application of gibberellin (GA) A₃. To understand the role of GAs in dormancy induction, endogenous GAs have been identified by Kovats retention indices and full mass spectra from capillary gas chromatography-mass spectrometry analysis of purified extract from dormant bulbils of Dioscorea opposita Thunb. These include GA₄, GA₉, GA₁₂, GA₁₉, GA₂₀, GA₂₄, GA₃₆, and GA₅₃; their presence suggests the occurrence of two biosynthetic pathways in D. opposita bulbils, the early 13-hydroxylation pathway and the non-13-hydroxylation pathway.     

Identification of Ten Gibberellins from Sporophytes of the Tree fern, Cyathea australis

Ten gibberellins (GAs) have been identified by Kovats retention indices and full mass spectra from GC-MS analysis of purified extracts of sporophytes of the tree-fern, Cyathea australis. These include the known GA₁, GA₄, GA₉, GA₁₅, GA₂₄, GA₃₅, and GA₅₈ and three new GAs, 12β-hydroxyGA₉ (GA₆₉), 12α-hydroxyGA₉ (GA₇₀) and 12β-hydroxyGA₄ (GA₇₁). The structure of GA₇₁ was established by the preparation and characterization of its methyl ester (as a metabolite of GA₄ methyl ester in a culture of prothallia of Lygodium japonicum).     

Endogenous Gibberellins in Aralia cordata

Eight gibberellins (GAs) were identified in extracts of buds of Aralia cordata by full scan GC/MS and by Kovats retention indices. These GAs comprised five GAs on the early-13-hydroxylation pathway [GA₁, GA₁₉, GA₂₀, GA₄₄, and GA₅₃] and three other GAs [GA₄, GA₁₅, and GA₃₇]. The major GAs were GA₁₉ and GA₄₄.     

Identification of gibberellins in leaf tissues of day-neutral strawberry (Fragaria × ananassa Duch.) cultivars

The endogenous gibberellins (GAs) in leaf tissues of two day-neutral cultivars (Rapella and Selva) of strawberry (Fragaria × ananassa Duch.) were analysed using combined gas chromatography -- mass spectrometry (GC-MS). Seven of the later members of the 13-hydroxylation GA biosynthetic pathway were identified, by comparison of Kovats retention indices and mass spectral data obtained for methyl ester trimethylsilyl ether derivatives, either with data obtained from authentic compounds or literature values. GA₁, GA₃, GA₈, GA₁₇, GA₁₉, GA₂₀ and GA₂₉ were detected in extracts of both cultivars.     

Dormancy in Peach (Prunus persica L.) Flower Buds : I. Floral Morphogenesis and Endogenous Gibberellins at the End of the Dormancy Period

Flower buds of peach (Prunus persica L.) trees, cv Novedad de Cordoba (Argentina), were collected near the end of the dormant period and immediately before anthesis. After removal of scale leaves, morphological observations of representative buds, made on transverse and longitudinal microtome sections, showed that all verticils making up the flower are present in an undifferentiated form during the dormant period (June). Flower buds collected at the end of dormant period (August) showed additional growth and differentiation, at which time formation of two ovules was beginning in the unicarpelar gynoecium. Dehiscence of anthers had not yet occurred 10 days before full bloom, and the ovules were still developing. Free endogenous gibberellin (GA)-like substances were quantified by bioassay (Tan-ginbozu dwarf rice microdrop) after SiO₂ partition column chromatography, reversed phase C18-high performance liquid chromatography, and finally Nucleosil [N(CH₃)₂]high performance liquid chromatography. Bioactive fractions were then subjected to capillary gas chromatography-mass spectrometry-selected ion monitoring (GC-MS-SIM). Gibberellins A₁, A₃, and A₈ were tentatively identified in peach flower buds using GC-SIM and Kovat's retention indices, and relative amounts approximated by GC-SIM (2:8:6 for GA₁, GA₃, and GA₈, respectively). The highest concentration (330 nanograms per gram dry weight) of free GA₁/GA₃ was found in dormant buds (June) and diminished thereafter. The concentration free of GA₁/GA₃ did not increase immediately prior to bud break. However, high GA₁/GA₃ concentrations occurred during stages where rate of growth and cellular differentiation of (mainly fertile) verticils can be influenced.     

The endogenous gibberellins of dwarf mutants of lettuce

The gibberellin (GA) content of E-1, a tall genotype of early flowering lettuce (Lactuca sativa L.), and of three selected GA-responsive dwarfs, dwf1, dwf2, and dwf2¹, has been determined using ¹³C-labeled internal standards and gas chromatographymass spectrometry (GC-MS). In the shoots of the E-1 parent, GA₁, 3-epi-GA₁, GA₃, GA₅, GA₈, GA₁₉, GA₂₀, GA₂₉, and GA₅₃ were identified by full scan GC-MS and Kovats retention indices. Purification by immunoaffinity chromatography selective for 13-hydroxy GAs, was necessary for GA identification. Relative to the parent E-1, the concentrations of GA₁, GA₈, GA₂₀, and GA₂₉ in the shoots of dwf2 plants were reduced to about 10% and in shoots of dwf2¹ plants to less than 50%. In dwf1 the levels of GA₁, GA₈, and GA₂₉ were also reduced to less than 50% of the parent E-1, but the level of GA₂₀ was fivefold higher than in E-1. Plant height was correlated with the endogenous levels of GA₁ and GA₈.     

Implication of Gibberellins in Head Smut (Sporisorium reilianum) of Sorghum bicolor

The head smut fungus, Sporisorium reilianum ([Kuhn] Landon and Fullerton), was shown to reduce plant height in infected Sorghum bicolor ([L.] Moench) plants. The major reductions occurred in the internodes nearest the panicle and were more severe in naturally infected than in inoculated plants. Less affected plants developed reproductively sterile panicles, and eventually smutted panicles developed phyllodied growths which progressed into leafy shoots. Extracts of smutted, sterile, and healthy (control) panicles of field-grown plants exhibited gibberellin (GA)-like activity in the dwarf rice bioassay. When extracts were purified and assayed with deuterium-labeled GA standards by gas chromatography-mass spectrometry-selected ion monitoring (GC-MS-SIM), GA₁, GA₃, GA₁₉, GA₂₀, and GA₅₃ were detected based on coelution with the standards, identical Kovats retention index values, and matching ion masses and relative abundances for three major ions. In addition, based on published Kovats retention index values, ion masses, and relative abundance values, GA₄, GA₇, GA₈, GA₁₄, GA₂₉, and GA₄₄ were tentatively identified. Quantitative analysis revealed that panicles of healthy control plants contained from 60 to 100% higher total concentrations of GAs than panicles of smutted plants. These comparisons were most striking for the early 13-hydroxylation pathway precursors GA₅₃, GA₄₄, and GA₁₉ but not for GA₂₀. Extracts of S. reilianum sporidia and culture medium exhibited GA-like bioactivity, and GA₁ and GA₃ were detected based on GC-MS-SIM assay with ²H-labeled internal standards. Quantitative analysis of these GAs showed increasing concentrations from 4 to 7 to 10 days of culture and a decline at 20 days. This is the first GC-MS-SIM detection of GAs in a non-Ascomycete fungus, and the disease symptoms and quantitative data suggested that fungal infection may interfere with biosynthesis of GAs by the host plant.     

Gibberellins in Leaves of Alstroemeria hybrida: Identification and Quantification in Relation to Leaf Age

In alstroemeria (Alstroemeria hybrida), leaf senescence is retarded effectively by the application of gibberellins (GAs). To study the role of endogenous GAs in leaf senescence, the GA content was analyzed by combined gas chromatography and mass spectrometry. Five 13-hydroxy GAs (GA₁₉, GA₂₀, GA₁, GA₈, and GA₂₉) and three non-13-hydroxy GAs (GA₉ and GA₄) were identified in leaf extracts by comparing Kováts retention indices (KRIs) and full scan mass sprectra with those of reference GAs. In addition, GA₁₅, GA₄₄, GA₂₄, and GA₃₄ were tentatively identified by comparing selected ion monitoring results and KRIs with those of reference GAs. A number of GAs were detected in conjugated form as well. Concentrations of GAs in alstroemeria changed with the development of leaves. The proportion of biologically active GA₁ and GA₄ decreased with progressive senescence and the fraction of conjugated GAs increased. Received May 26, 1997; accepted August 12, 1997     

Endogenous Gibberellins from Sporophytes of Two Tree Ferns, Cibotium glaucum and Dicksonia antarctica

Gibberellin A₁ (GA₁), 3-epi-GA₁, GA₄, GA₉, 11α-hydroxyGA₁₂, 12α-hydroxyGA₁₂, GA₁₅, GA₁₇, GA₁₉, GA₂₀, GA₂₅, GA₃₇, GA₄₀, GA₅₈, GA₆₉, GA₇₀, and GA₇₁ have been identified from Kovats retention indices and full scan mass spectra by capillary GC-MS analyses of purified extracts from sporophytes of the tree fern, Cibotium glaucum. Abscisic acid, dihydrophaseic acid, an epimer of 4′-dihydrophaseic acid, and the epimeric ent-6α, 7α, 16α, 17-(OH)₄ and ent-6α, 7α, 16β, 17-(OH)₄ derivatives of ent16, 17-dihydrokaurenoic acid, in addition to the epimeric 16α, 17- and 16β, 17-dihydroxy-16, 17-dihydro derivatives of GA₁₂, were also identified in extracts of C. glaucum. An oxodihydrophaseic acid and a hydroxydihydrophaseic acid were also detected. In extracts of sporophytes of Dicksonia antarctica, GA₄, GA₉, 12α- and 12β-hydroxyGA₁₂, GA₁₅, GA₂₅, and GA₃₇ were identified by the same criteria, as well as abscisic acid, phaseic acid, 8′-hydroxymethylabscisic acid and dihydrophaseic acid. This is the first time that GA₄₀ has been identified in a higher plant; it is also the first report of the natural occurrence of the two gibberellins, 11α- and 12β-hydroxyGA₁₂. The total gibberellin (GA) content in C. glaucum (tall) was at least one order of magnitude greater than that of D. antarctica (dwarf) based on total ion current response in GC-MS and bioassay data. Abscisic acid was a major component of D. antarctica and the oxodihydrophaseic acid was a major component of C. glaucum.     

Endogenous Gibberellins in the Xylem Exudate from Apple Trees

In the xylem exudate extracted from the current-year stems of apple (Malus domestica Borkh.), gibberellins A₁₅, A₁₇, A₁₈, A₁₉, A₂₃, A₄₄, and A₅₃ were identified, and 16,17-dihydro-17-hydroxy GA₁₉ was presumed from full-scan mass spectra and Kovats retention indices.     

Identification of Gibberellins A(1), A(5), A(29), and A(32) from Immature Seeds of Apricot (Prunus armeniaca L.)

Gibberellins (GAs) A₁, A₅, and A₂₉ were identified, and also GA₃₂ was confirmed, as endogenous GAs of immature seeds (3-4 weeks after anthesis, 0.25-0.5 gram fresh weight) of apricot (Prunus armeniaca L.) based on capillary gas chromatography (GC), retention time (Rt), and selected ion monitoring (SIM), in comparison with authentic standards. Fractions subjected to GC-SIM were purified and separated using sequential solvent partitioning → paper chromatography → reverse phase C₁₈ high performance liquid chromatography (HPLC) → bioassay on dwarf rice cv Tan-ginbozu. Two other peaks of free GA-like bioactivity (microdrop and immersion dwarf rice assays) were eluted from C₁₈ HPLC at Rts where GA_4/7 and GA₈ (or other GAs with similar structures) would elute. Also, three unidentified GA glucoside-like compounds (based on bioactivity on the immersion assay, and no bioactivity on the microdrop assay) were noted. There were very high amounts of GA₃₂ (112 ng of GA₃ equivalents per gram fresh weight), and minor amounts (0.5 ng of GA₃ equivalents) for each of GA₁ and GA₅, respectively, based on the microdrop assay.     

Metabolism of tritiated gibberellin a(20) in maize

After the application of 2.36 Curies per millimole [2,3-³H]gibberellin A₂₀ (GA₂₀) to 21-day-old maize (Zea mays L., hybrid CM7 × CM49) plants, etiolated maize seedlings, or maturing maize cobs, a number of ³H-metabolites were observed. The principal acidic (pH 3.0), ethyl acetate-soluble metabolite was identified as [³H]GA₁ on the basis of co-chromatography with standard [³H]GA₁ on SiO₂ partition, high resolution isocratic elution reverse phase C₁₈ high performance liquid chromatography and gas-liquid chromatography radiocounting. Two other acidic metabolites were identified similarly as [³H]GA₈ and C/D ring-rearranged [³H]GA₂₀, although gas-liquid chromatography radiocounting was not performed on these metabolites. Numerous acidic, butanol-soluble (e.g. ethyl acetate-insoluble) metabolites were observed with retention times on C₁₈ high performance liquid chromatography radiocounting similar to those of authentic glucosyl conjugates of GA₁ and GA₈, or with retention times where conjugates of GA₂₀ would be expected to elute. Conversion to [³H]GA₁ was greatest (23% of methanol extractable radioactivity) in 21-day-old maize plants. In etiolated maize seedlings, the C/D ring-rearranged [³H]GA₂₀-like metabolite was the major acidic product, while conversion to [³H]GA₁ was low.     

Identification of a Novel Gibberellin (GA85) in Very Young Seedlings of Brassica campestris cv. Tobin

A new gibberellin (GA) was identified from extracts of cotyledons of 7 day-old canola seedlings (Brassica campestris cv. Tobin). This GA is 12α-hydroxy-GA₁ and has been assigned the trivial name of GA₈₅. Isolation was monitored by the Tan-ginbozu dwarf rice micro-drop assay after each high-performance liquid chromatography (HPLC) step. Identification was based on Kovats retention index (KRI) and the mass spectrum of the methyl ester, trimethylsilyl ether (MeTMSi) derivative after analysis by gas chromatography-mass spectrometry (GC-MS) in comparison with an authentic sample of 12α-hydroxy-GA₁. Based on quantitation by the dwarf rice micro-drop assay, GA₈₅ is one of the major biologically active GAs in cotyledons of young canola seedlings.     

Thermoperiodic control of stem elongation and endogenous gibberellins in Campanula isophylla

The effect of day/night temperature regimes on stem elongation and on the content of endogenous gibberellins (GAs) in vegetatively propagated plants of Campanula isophylla cv. Hvit have been studied. Compared with a constant temperature regime at 18°C (18/18°C), stem and internode elongation was enhanced significantly by a combination of high day/low night temperature (21/15°C) and inhibited by an opposite regime (15/21°C). Gibberellins A₁, A₁₉, A₄₄, A₅₃, and A₉₇ were identified as endogenous components in Campanula. (GA₉₇ was earlier referred to as 2-OH-GA₅₃.) Quantitative analysis of the endogenous GAs indicates that temperature regimes that stimulate elongation growth are accompanied by an increase in the level of GA₁, GA₁₉, and GA₄₄. On the other hand, in plants grown under conditions that reduced stem elongation growth, there was an increased level of GA₉₇.Abbreviations DIF difference between day temperature and night temperature - GA gibberellin - HPLC high performance liquid chromatography - GC-MS gas chromatography-mass chromatography - SPE solid phase extraction - TMS trimethylsilyl - MSTFA N-methyl-N-TMS-trifluoroacetamide - KRI Kovats retention index - SIM selected ion monitoring - D2 deuterated     

Microbiological conversion of 12-oxygenated and other derivatives of ent-kaur-16-en-19-oic acid by Gibberella Fujikuroi, mutant B1-41a

The metabolism of several ring C and D-functionalized ent-kaur-16-en-19-oic acids by cultures of Gibberella fujikuroi, mutant B1-41a, to the corresponding derivatives of the normal fungal gibberellins (GAs) and ent-kaurenoids is described. A range of 12α- and 12β-hydroxyGAs and ent-kaurenoids are characterized by their mass spectra and GC Kovats retention indices. The mass spectral and GC data are used to identify the 12α-hydroxy derivatives of GA₁₂, GA₁₄, GA₃₇ and GA₄ (GA₅₈), and of the 12β-hydroxy derivatives of ent-7α-hydroxy- and ent-6α, 7α-dihydroxykaurenoic acids, in seeds of Cucurbita maxima. Similarly the metabolites of GA₉, formed in seeds of Pisum sativum and cultures of G.fujikuroi, mutant B1-41a, are identified as 12α-hydroxyGA₉. ent-11β-Hydroxy- and ent-11-oxo-kaurenoic acids are metabolized by the fungus to the corresponding 11-oxygenated derivatives of the normal fungal ent-kaurenoids and some C₂₀-GAs; no 11-oxygenated C₁₉-GAs are formed. Grandiflorenic acid, 11β-hydroxygrandiflorenic acid, attractyligen and ent-15β-hydroxykaurenoic acid are metabolized to unidentified products.     

Qualitative and Quantitative Analyses of Gibberellins in Vegetative Shoots of Normal, dwarf-1, dwarf-2, dwarf-3, and dwarf-5 Seedlings of Zea mays L

Gibberellins A₁₂ (GA₁₂), GA₅₃, GA₄₄, GA₁₉, GA₁₇, GA₂₀, GA₂₉, GA₁, and GA₈ have been identified from extracts of vegetative shoots of normal (wild type) maize using full scan capillary gas chromatography-mass spectrometry and Kovats retention indices. Seven of these gibberellins (GAs) have been quantified by capillary gas chromatography-selected ion monitoring using internal standards of [¹⁴C₄]GA₅₃, [¹⁴C₄]GA₄₄, [²H₂] GA₁₉, [¹³C₁]GA₂₀, [¹³C₁]GA₂₉, [¹³C₁]GA₁, and [¹³C₁]GA₈. Quantitative data from extracts of normal, dwarf-1, dwarf-2, dwarf-3, and dwarf-5 seedlings support the operation of the early 13-hydroxylation pathway in vegetative shoots of Zea mays. These data support the positions in the pathway blocked by the mutants, previously assigned by bioassay data and metabolic studies. The GA levels in dwarf-2, dwarf-3, and dwarf-5 were equal to, or less than, 2.0 nanograms per 100 grams fresh weight, showing that these mutants are blocked for steps early in the pathway. In dwarf-1, the level of GA₁ was very low (0.23 nanograms per 100 grams fresh weight) and less than 2% of that in normal shoots, while GA₂₀ and GA₂₉ accumulated to levels over 10 times those in normals; these results confirm that the dwarf-1 mutant blocks the conversion of GA₂₀ to GA₁. Since the level of GAs beyond the blocked step for each mutant is greater than zero, each mutated gene probably codes for an altered gene product, thus leading to impaired enzyme activities.     

Identification of Gibberellins in Spinach and Effects of Light and Darkness on their Levels

The endogenous gibberellin (GA) content of spinach (Spinacia oleracea) was reinvestigated by combined gas chromatography-mass spectrometry analysis. The 13-hydroxy GAs: GA₅₃, GA₄₄, GA₁₉, GA₁₇, GA₂₀, GA₅, GA₁, GA₂₉, and GA₈; the non-3, 13-hydroxy GAs: GA₁₂, GA₁₅, GA₉, and GA₅₁; and the 3β-hydroxy GAs: GA₄, GA₇, and GA₃₄, were identified in spinach extracts by comparing full-scan mass spectra and Kovats retention indices with those of reference GAs. In addition, spinach plants contained GA₇-isolactone, 16,17-dihydro-17-hydroxy-GA₅₃, GA₂₉-catabolite, 3-epi-GA₁, and 10 uncharacterized GAs with mass spectra indicative of mono- and dihydroxy-GA₁₂, monohydroxy-GA₂₅, dihydroxy-GA₂₄, and dihydroxy-GA_g. The effect of light-dark conditions on the GA levels of the 13-hydroxylation pathway was studied by using labeled internal standards in selected ion monitoring mode. In short day, the GA levels were higher at the end of the light period than at the end of the dark period. Levels of GAs at the end of each short day were relatively constant. During the first supplementary light period of long day treatment, GA₅₃ and GA₁₉ declined dramatically, GA₄₄ and GA₁ decreased slightly, and GA₂₀ increased. During the subsequent high-intensity light period, the GA₂₀ level decreased and the levels of GA₅₃, GA₄₄, GA₁₉, and GA₁ increased slightly. Within 7 days after the beginning of long day treatment, similar patterns for GA₅₃ and GA₁₉ occurred. Furthermore, when these plants were transferred to darkness, an increase in the levels of GA₅₃ and GA₁₉ was observed. These results are compatible with the idea that in spinach, the flow through the GA biosynthetic pathway is much enhanced during the high-intensity light period, although GA turnover occurs also during the supplementary period of long day, both effects being responsible for the increase of GA₂₀ and GA₁ in long day.     

Light effects on endogenous levels of gibberellins in photoblastic lettuce seeds

Gibberellin A₁ (GA₁), 3-epi-GA₁ GA₁₇, GA₁₉, GA₂₀, and GA₇₇ were identified by Kovats retention indices and full-scan mass spectra from gas chromatography-mass spectrometry analysis of a purified extract of mature seeds of photoblastic lettuce (Lactuca sativa L. cv. Grand Rapids). Non-13-hydroxylated GAs such as GA₄ and GA₉ were not detected even by highly sensitive radioimmunoassay. These results show that the major biosynthetic pathway of GAs in lettuce seeds is the early-13-hydroxylation pathway leading to GA₁, which is suggested to be physiologically active in lettuce seed germination. Quantification of endogenous GAs in the lettuce seeds by gas chromatography-selected ion monitoring using deuterated GAs as internal standards indicated that the endogenous level of GA₁ increased to a level about three times that of dark control 6 h after a brief red light irradiation, and that far-red light given after red light suppressed the effect of red light. The contents of GA₂₀ and GA₁₉ were not affected by the red light irradiation. Evidence is also presented that 3-epi-GA₁ is a native GA in the lettuce seeds.     

Influence of an inhibitor of gibberellin biosynthesis, paclobutrazol, on apple seed gibberellin content

Tissue-culture-propagated own-rooted cv. Spartan apple trees (Malus domestica Borkh.) planted in 1979 were treated in 1983 and 1985 via a soil-line trunk drench with the plant growth retardant paclobutrazol [(2RS, 3RS)-1-(4-chlorophenyl)-4.4-dimethyl-2-(1,2, 4-triazol-1-yl) pentan-3-ol]. Seeds of immature fruits from untreated and treated trees were sampled in 1989 ca 75 days after full bloom. After seeds were freeze-dried, gibberellins (GAs) were extracted, purified and fractionated via C₁₈ reversed-phase high-performance liquid chromatography (HPLC). Gibberellins A₁, A₃, A₄, A₇, A₈, A₉, A₁₅, A₁₇, A₁₉, A₂₀, A₂₄, A₃₄, A₃₅, A₄₄, A₅₁, A₅₃, A₅₄, A₆₁, A₆₂, A₆₃ and A₆₈ were identified by using C₁₈ HPLC, gas chromatography-selected ion monitoring and Kovats retention indices. Eight of the GAs identified were also quantified by using deuterated internal standards. The paclobutrazol applications caused a 55% reduction of vegetative shoot elongation in 1989, but both treated and untreated trees had developed a biennial bearing pattern by that time (heavy bloom or “on year’in 1989). Levels of early 13-hydroxylation pathway GAs, viz. GA₅₃, GA₁₉, GA₂₀, GA₁ and also GA₃, were not altered by treatment. However, GA₄, GA₇ and GA₉ were increased 13.4, 6.5 and 3.8 times, respectively, in seeds of fruit from treated compared to untreated trees.     

Gibberellins inCitrus sinensis: A comparison between seeded and seedless varieties

The gibberellin (GA) content of the reproductive organs ofCitrus sinensis (L.) Osb., cv. Bianca Comuna and the seedless variety, Salustiana, were examined by combined gas chromatography-mass spectrometry (GC/MS) at different stages of development. Gibberellins A₁, A₂₀, and A₂₉ were identified in the reproductive buds of both cultivars 21 days prior to anthesis and in fruits 35 days after anthesis by comparison of their mass spectra and Kovats retention indices with those of standards. In addition, three uncharacterized isomers of GA₁ were detected, one in buds and two in fruits. The presence of GA₄ in both tissues, and of GA₈ in the reproductive buds, was indicated by the occurrence of characteristic ions at the expected retention times, although their spectra were too weak for full identification. Vegetative shoots of cv. Salustiana contained gibberellins A₁, A₁₉, A₂₀, and A₂₉, and the unidentified isomer of GA₁ present in reproductive buds. The presence of trace amounts of gibberellins A₈ and A₁₇ was also indicated. Although the two varieties did not differ qualitatively in the GAs present during flower and fruit development, the seedless variety contained slightly greater amounts. The concentrations of gibberellins A₁, A₄, and A₂₀ were determined by gas chromatography-selected ion monitoring (GC/SIM) throughout ovary development and early fruit growth. In both varieties, the maximum GA₁ concentration occurred at anthesis. Highest concentrations of gibberellins A₂₀ and A₄ were found in fruit 35 days after anthesis, although the GA₁ concentration at this stage remained low.