TRANSPORT AND METABOLISM OF GIBBERELLINS IN RELATION TO FLOWER BUD DIFFERENTIATION IN NORWAY SPRUCE (PICEA-ABIES)

A mixture of tritiated and deuterated gibberellin A(4) (GA(4)) was inj ected into the xylem of Norway spruce (Picea abies (L.) Karat) propagu les, below an elongating shoot, or applied directly on the needles of an elongating shoot. The distribution of [H-2(2)] GA(4) and [H-3]GA(4) in the needles, stems and buds was determined after 4, 12 and 24 h. A fter 4 h, most of the xylem-injected GA(4) was found in the needles, w hereas after 24 h, most of the GA(4) was found in the stem, with a sma ll portion in the lateral buds. Of the GA(4) applied to the needles, 5 1% of the radioactivity recovered after 24 h was found in the stem and 2% in the lateral buds. Mixtures of tritiated and deuterated GA(4) an d GA(9) were injected into elongating shoots of one abundant-flowering family and one limited-flowering family, grown either under condition s inductive for flowering (hot and dry, HD) or under noninductive cond itions for flowering (cool and wet, CW). Shoots of both CW-and HD-trea ted propagules converted [H-2(2)]GA(9) to [H-2(2)]GA(51), [H-2(2)]GA(4 ), [H-2(2)]GA(34) and [H-2(2)]GA(1), whereas [H-2(2)]GA(4) was convert ed to [H-2(2)]GA(34), [H-2(2)]GA(1) and [H-2(2)]GA(8). In shoots of bo th CW-treated clones, the main metabolite of [H-3]GA(9) was in the GA( 51) region. The HD-treated propagules converted more [H-3]GA(9) to put ative GA(4) than the CW-treated propagules. The main metabolite of [H- 3]GA(4) was in the GA(34) region. Radioactive metabolites were also fo und in the GA(1) and GA(8) regions.