Naomi Oyama

Identification of Antheridiogens in Lygodium circinnatum and Lygodium flexuosum.

Antheridiogens in two species of Schizaeaceous ferns, Lygodium circinnatum and Lygodium flexuosum, were analyzed by gas chromatography-mass spectrometry. In L. circinnatum, gibberellin A73 (GA73) methyl ester (GA73-Me), which had originally been identified in L. japonicum, was identified as a principal antheridiogen, and the methyl esters of five known GAs (GA9, GA20, GA70, GA88, and 3-epi-GA88) were also identified as minor antheridiogens. In addition, four compounds corresponding to isomers of monohydroxy-GA73-Me were detected. One of these was shown to be 12[beta]-hydroxy-GA73-Me, the parent acid of which has been allocated the GA assignment GA96. The other three compounds, tentatively named X1, X2, and X3, have not been fully characterized. In L. flexuosum, GA73-Me was also identified as a major antheridiogen, with X2 being detected as a minor one. The total antheridium-formation activity in the culture medium of 7-week-old prothallia of L. circinnatum and L. flexuosum was more than 1000 times higher than that of L. japonicum. On the other hand, the response of gametophytes of the former two Lygodium ferns to GA73-Me was more than 100 times lower than that of L. japonicum.

Biosynthesis of antheridic acid, the principal antheridiogen in Anemia phyllitidis

Abstract [ 2 H 2 ,]9,15-Cyclo-GA 9 and [ 2 H 2 ]3α-hydroxy-9,15-cyclo-GA 9 were fed to prothallia of the fern, Anemia phyllitidis . The metabolises from these feeds were subjected to full-scan GC-MS to confirm the conversion of [ 2 H 2 ]9,15-cyclo-GA 9 into [ 2 H 2 ]3α-hydroxy-9,15-cyclo-GA 9 and [ 2 H 2 ]antheridic acid, and of [ 2 H 2 ]3α-hydroxy-9,15-cyclo-GA 9 into [ 2 H 2 ]antheridic acid. These results indicated that antheridic acid is biosynthesized from 9,15-cyclo-GA 9 via 3α-hydroxy-9,15-cyclo-GA 9 in A. phyllitidis . It was also shown that 3α-hydroxy-9,15-cyclo-GA 9 is a native antheridiogen in A. phyllitidis . Biological activity of 9,15-cyclo-GA 9 , and 3α-hydroxy-9,15-cyclo-GA 9 are also reported.

Identification of Gibberellins and 9,15-Cyclogibberellins in Developing Apple Seeds

Endogenous gibberellins (GAs) and GA-related compounds at two different developmental stages of apple seeds(Malus domestica cv. McIntosh) were analyzed by gas chromatography-mass spectrometry.From the seeds at ca. 10 and/or 14 weeks after full-bloom, the following GAs and 9,15-cyclogibberellins (9,15-cyclo-GAs) were identified by a comparison of their mass spectra and Kovats retention indices with those of authentic specimens: GA4, GA7, GA9, GA12, GA17, GA19, GA20, GA25, GA34, GA35, GA45,GA53, GA54, GA61, GA62, GA63, GA70, GA73, GA80, GA84, GA88, 3-epi-GA4, 3-epi-GA54, and 3-epi-GA63, 9,15-cyclo-GA9, lβ-hydroxy-9,15-cyclo-GA9, 2β-hydroxy-9,15-cyclo-GA9, 3α-hydroxy-9,15- cyclo-GA9, 3β-hydroxy-9,15-cyclo-GA9, and llβ-hydroxy-9,15-cyclo-GA9. The major components in the seeds at ca. 10 weeks after full-bloom were GA4, GA7, GA9, GA17, GA35, GA54, GA62, GA80, and GA84, and those in the seeds at ca. 14 weeks after full-bloom were GA17, GA25, GA45, GA62, GA63, GA80,GA84, 9,15-cyclo-GA9, and 1β-, 3β-, and 11β-hydroxy-9,15-cyclo-GA9. New GA number (GA103 _ 108) have been allocated to 9,15-cyclo-GA9, and 1β-, 2β-, 3β-, 3α-, and 11β-,hydroxy-9,15-cyclo-GA9, respectively (1β- and 3α-hydroxy-9,15-cyclo-GA9 were identified previously as fern anteridiogens, although GA numbers have not previously been assigned to these compounds). This is the first report of the co-occurrence of GA73 and 9,15-cyclo-GAs in higher plants.

3-epi-GA63, antheridiogen in Anemia phyllitidis

Abstract 3-Epi-Gibberellin A 63 (3-epi-GA 63 ) was identified by full-scan GC-mass spectrometry of a purified extract from culture media of prothallia of the fern, Anemia phyllitidis . This is the third antheridiogen, following antheridic acid and 3α-hydroxy-9,15-cyclo-GA 9 , in this species. 3-Epi-GA 63 showed slightly less activity than antheridic acid in antheridial formation and dark spore germination assays.

Biosynthesis of GA73 Methyl Ester in Lygodium Ferns

Biosynthesis of GA73 methyl ester (GA73-Me), the principal antheridiogen in Lygodium ferns, was investigated. From the methanol extract of prothallia of Lygodium circinnatum, GA25, GA73, GA73-Me, GA88-Me, and a few unknown GA73 derivatives were detected by GC-MS. Because the presence of GA25 suggests that GA24, a direct precursor of GA25, could also be present in L. circinnatum prothallia, we used feeding experiments to investigate the possibility that GA24 is a precursor of GA73-Me. In L. circinnatum prothallia, [2H2]GA24 was converted into [2H2]GA73-Me and a trace amount of [2H2]GA9-Me, whereas [2H3]GA9 was converted into [2H3]GA9-Me and [2H3]monohydroxy-GA9-Me. Because GA73-Me, GA9-Me, and their monohydroxy derivatives had been identified by GC-MS from the culture medium of L. circinnatum prothallia, our results suggest that GA73-Me is biosynthesized from GA24 via GA73, and that neither GA9 nor GA9-Me is a precursor of GA73-Me. Though the possibility had been suggested that GA73-Me is biosynthesized from 9,15-cyclo-GA9 (GA103), [2H2]GA103 was not converted into [2H2]GA73-Me.

An antheridiogen, 13-hydroxy-GA73 methyl ester (GA109), from the fern Lygodium circinnatum

Abstract The structure of a new gibberellin-like antheridiogen from gametophytes of the fern Lygodium circinnatum has been confirmed as the methyl ester of 9,11-didehydro-GA20 by synthesis of an authentic sample from gibberellic acid (GA3). Comparative bioassays of the synthetic compound as an antheridium inducing substance in Lygodium japonicum have demonstrated that it is highly potent, showing activity down to 10−14 M concentrations, and that the high level of activity is correlated with the incorporation of the 9,11-alkene bond.

Gibberellins and Antheridiogens in Prothallia and Sporophytes of Anemia phyllitidis

The following gibberellins (GAs) and antheridiogens were identified by their mass spectra and Kovats retention indices from combined gas chromatography-mass spectrometry of purified extracts of the prothallia and sporophytes of Anemia phyllitidis, a Schizaeaceous fern: a trace amount of GA9 (4-week-old prothallia); GA9, GA24, GA25, antheridic acid and 3-epi-GA63 (6-week-old prothallia); and GA4, GA9, GA15, GA19, GA20, and GA24 [young sporophytes (younger than one year old) and/or old sporophytes (between one- and two years old). Of these compounds, GA24, GA9, and GA4 were quantified by gas chromatography-selected ion monitoring, using (2)H-GAs as internal standards, and the content of antheridic acid, the principal antheridiogen, was evaluated by a radioimmunoassay which we have developed. The results indicate that endogenous levels of GAs and antheridiogens in prothallia began to increase rapidly between 4 and 6 weeks after sowing, the contents of antheridic acid and GA24, the most abundant GA in 6-week-old prothallia, being 107.4 and 37.9 ng/g fresh weight, respectively. The most abundant GA in the sporophytes was GA9, the content in young and old sporophytes being 15.3 and 7.3 ng/g fresh weight, respectively.

Identification of Endogenous Gibberellins in the Leaves and Xylem Sap of Tea Plants

Endogenous gibberellins (GAs) in the young leaves and xylem sap of tea plants (Camellia sinensis L.) were analyzed by GC-MS. The following GAs were identified by comparing their mass spectra and KRIs with those of authentic specimens: GA9 and GA20 in the leaves; GA9, GA12, GA15, GA20, GA44, GA51 and GA53 in the xylem sap.