Biological activity, identification and quantification of gibberellins in seedlings of Norway spruce (Picea abies) grown under different photoperiods

Short photoperiod induces growth cessation in seedlings of Norway spruce (Picea abies [L.] Karst.). Application of different gibberellins (GAs) to seedlings growing under a short photoperiod show that GA(9) and GA(20) can not induce growth. In contrast application of GA(1) and GA(4) induced shoot elongation. The results indicate that 3 beta-hydroxylation of GA(9) to GA(4) and of GA(20) to GA(1) is under photoperiodic control. To confirm that conclusion both qualitative and quantitative analyses of endogenous GAs were performed. GA(1), GA(3), GA(4), GA(7), GA(9), GA(12), GA(15), GA(20), GA(29), GA(34) and GA(51) were identified by combined gas chromatography-mass spectrometry in shoots of Norway spruce seedlings. The effect of photoperiod on GA levels was determined by using deuterated and C-14-labelled GAs as internal standards. In short days, the amounts of GA(9), GA(4) and GA(1) are less than in plants grown in continuous light. There is no significant difference in the amounts of GA(3), GA(12) and GA(20) between the different photoperiods. The lack of accumulation of GA(9) and GA(20) under short days is discussed.