Identification,quantitation and distribution of gibberellins in fruits of Pisum sativum L. cv. Alaska during pod development

In addition to the previously-reported gibberellins: GA₁; GA₈, GA₂₀ and GA₂₉ (García-Martínez et al., 1987, Planta 170, 130–137), GA₃ and GA₁₉ were identified by combined gas chromatography-mass spectrometry in pods and ovules of 4-d-old pollinated pea (Pisum sativum cv. Alaska) ovaries. Pods contained additionally GA₁₇, GA₈₁ (2-hydroxy GA₂₀) and GA₂₉-catabolite. The concentrations of GA₁, GA₃, GA₈, GA₁₉, GA₂₀ and GA₂₉ were higher in the ovules than in the pod, although, with the exception of GA₃, the total content of these GAs in the pod exceeded that in the seeds. About 80% of the GA₃ content of the ovary was present in the seeds. The concentrations of GA₁₉ and GA₂₀ in pollinated ovaries remained fairly constant for the first 12 ds after an thesis, after which they increased sharply. In contrast, GA₁ and GA₃ concentrations were maximal at 7 d and 4–6 d, respectively, after anthesis, at about the time of maximum pod growth rate, and declined thereafter. Emasculated ovaries at anthesis contained GA₈, GA₁₉ and GA₂₀ at concentrations comparable with pollinated fruit, but they decreased rapidly. Gibberellins a₁ and A₃ were present in only trace amounts in emasculated ovaries at any stage. Parthenocarpic fruit, produced by decapitating plants immediately above an emasculated flower, or by treating such flowers with 2,4-dichlorophenoxyacetic acid or GA₇, contained GA₁₉ and GA₂₀ at similar concentrations to seeded fruit, but very low amounts of GA₁ and GA₃ Thus, it appears that the presence of fertilised ovules is necessary for the synthesis of these last two GAs. Mature leaves and leaf diffusates contained GA₁, GA₈, GA₁₉ and GA₂₀ as determined by combined gas chromatography-mass spectrometry using selected ion monitoring. This provides further evidence that vegetative tissues are a possible alternative source of GAs for fruit-set, particularly in decapitated plants.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - FW fresh weight - GA_n gibberellin A_n - GC-MS combined gas chromatography-mass spectrometry - HPLC high-performance liquid chromatography - KRI Kovats retention index - m/z mass to charge ratio We thank Mr M.J. Lewis for qualitative GC-MS analyses and Ms M.V. Cuthbert (LARS), R. Martinez Pardo and T. Sabater (IATA) for technical assistance. We are also grateful to Professor B.O. Phinney, University of California, Los Angeles, for gifts of 17-¹³C]GA₈ and -GA₂₉ and to Mr Paul Gaskin, University of Bristol, for the mass spectrum of GA₂₉-catabolite and for a sample of GA₈₁ The work in Spain was supported by Dirección General de Investigación Cientifica y Técnica (grant PB87-0402 to J.L.G.-M.). We also acknowledge the British Council and Ministerio de Educacion y Ciencia for travel grants through Accion Integrada Hispano-Britanica 56/142 (J.L.G.-M. and P.H.).