GIBBERELLINS IN CITRUS-SINENSIS - A COMPARISON BETWEEN SEEDED AND SEEDLESS VARIETIES

The gibberellin (GA) content of the reproductive organs of Citrus 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. © 1990 Springer-Verlag New York Inc.