Quantitation of gibberellins A1, A3, A4, A9and an A9-conjugate in good- and poor-flowering clones of Sitka spruce (Picea sitchensis) during the period of flower-bud differentiation
✍ Scribed by Thomas Moritz; J. Julian Philipson; Per Christer Odén
- Publisher
- Springer-Verlag
- Year
- 1990
- Tongue
- English
- Weight
- 562 KB
- Volume
- 181
- Category
- Article
- ISSN
- 0032-0935
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✦ Synopsis
The levels of endogenous gibberellin A a (GA a), GA3, GA4, GA9 and a cellulase-hydrolysable GA9-conjugate in needles and shoot stems of Sitka spruce [Picea sitchensis (Bong.) Carr.] grafts with different coning or flowering histories were estimated by combined gas chromatography-mass spectrometry selected ion monitoring using deuterated GA3, GA4 and GA9 as internal standards. The samples were taken at the approximate time of the start of flower-bud differentiation, i.e. when the shoots had elongated approx. 95% of the final length. The needles of the good-flowering clones contained 11-12 ng per g fresh weight (FW) and 15-28 ng. (g FW)-a of GAg-conjugate and GA9, respectively. The shoot stems of the same material contained no detectable amounts of GA9-conjugate and 1 I-15 ng. (g FW)-1 of GA 9. The amounts of GAg-conjugate and GA9 were apparently lower in the poor-flowering clones, the needles containing 4-9 ng-(g FW)-1 and 7 17ng. (g FW)-1, respectively. Also in this material the shoot stems contained no detectable amounts of GA9-conjugate. The amounts of GA4 were very small in both materials, ranging from 1-1.6 ng-(g FW)-a. The good-flowering clones contained no detectable amounts of the more polar gibberellins, GAa and GA3. The poor-flowering clones, on the other hand, contained high levels of GAa, 17-19ng'(gFW) -j in the needles and 10-13 ng.(g FW)-I in the shoot stems, and also smaller amounts of GA3, 2-3 ng.(g FW)-1 in the needles and approx. I ng-(g FW)-a in the shoot stems. The results demonstrate differences in GA-metabolism between the poor-and the good-flowering clones. The higher amounts of GA9-conjugate and GA9 might indicate a higher capacity for synthesizing GA4 in the good-flowering material. This synthesis does not, however, result in a build-up of the GA4-pool, maybe because of a high rate of turnover. Gibberellin A 4 was apparently neither hydroxylated to GAa nor converted to GAa in the goodflowering material, as was the case in the poor-flowering Abbreviations . FW = fresh weight; GA. = gibberellin An ; HPLC = high-performance liquid chromatography material. This might indicate that gibberellin metabolism in the poor-flowering material is directed towards GA1 and GA3, GAs preferentially used in vegetative growth.