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 injected into the xylem of Norway spruce (Picea abies (L.) Karst) propagules, below an elongating shoot, or applied directly on the needles of an elongating shoot. The distribution of [(2)H(2)]GA(4) and [(3)H]GA(4) in the needles, stems and buds was determined after 4, 12 and 24 h. After 4 h, most of the xylem-injected GA(4) was found in the needles, whereas after 24 h, most of the GA(4) was found in the stem, with a small portion in the lateral buds. Of the GA(4) applied to the needles, 51% 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) and GA(9) were injected into elongating shoots of one abundant-flowering family and one limited-flowering family, grown either under conditions inductive for flowering (hot and dry, HD) or under noninductive conditions for flowering (cool and wet, CW). Shoots of both CW- and HD-treated propagules converted [(2)H(2)]GA(9) to [(2)H(2)]GA(51), [(2)H(2)]GA(4), [(2)H(2)]GA(34) and [(2)H(2)]GA(1), whereas [(2)H(2)]GA(4) was converted to [(2)H(2)]GA(34), [(2)H(2)]GA(1) and [(2)H(2)]GA(8). In shoots of both CW-treated clones, the main metabolite of [(3)H]GA(9) was in the GA(51) region. The HD-treated propagules converted more [(3)H]GA(9) to putative GA(4) than the CW-treated propagules. The main metabolite of [(3)H]GA(4) was in the GA(34) region. Radioactive metabolites were also found in the GA(1) and GA(8) regions.