Résumé
Flowering in Pinaceae conifers can bebrought about by the application of lesspolar gibberellins (GAs), especially GA4/7applied singly or in combination with otherplant growth regulators (such as naphthylacetic acid) or culture treatments, such ashigh temperature, water stress, girdling orroot-pruning (Pharis and Ross, 1986).GAs seem to be essential in the floweringinduction strategy. It is therefore importantto know the endogenous GAs of a speciesbefore trying to interpret any physiologicalrole of endogenously or exogenouslyapplied GAs.The level of endogenous GAs in planttissues is generally very low (1-10 ng/gfresh weight). Consequently, selectivemethods must be used to analyze GAs.One course of action is to use selectiveGA immunoassays to detect immunoreac-tive components in high performanceliquid chromatography (HPLC) eluates.Weiler and his coworkers (Weiler andWieczoreck, 1981; Aztorn and Weiler,1983a, b) have shown that immunologicalanalyses of GAs could be effective andpromising.We have developed a procedure, com-bining HPLC separation and enzyme-link-ed immunosorbent assay (ELISA), whichcan recognize a limited number of GAs.We have analyzed the effect of flower-inducing treatments on GA levels fromjuvenile trees. This paper reports prelimi-nary results on the analysis of several GA-like substances in elongating shoots ofDouglas fir (Pseudotsuga menziesii Mirb.)with or without a flower-inducing treat-ment, independent of any flowering re-sponse on such juvenile trees.