QUANTIFICATION OF GA1, GA3, GA4, GA7, GA8, GA9, GA19 AND GA20 - AND GA20 METABOLISM IN DORMANT AND NONDORMANT BEECHNUTS

The endogenous levels of GA(1), GA(3), GA(4), GA(7), GA(8), GA(9), GA( 19) and GA(20) were determined in beech seeds (Fagus sylvatica L.) tre ated with different dormancy breaking treatments. Gibberellins were an alysed separately in cotyledons and embryo axes. After purification of the extracts, GAs were quantified by GC-MS-selected ion monitoring (G C-MS-SIM) with deuterated GAs as internal standards. The results showe d that GAs corresponding to the 13-OH pathway seemed to be involved in dormancy breaking. Strong differences in GA(1), GA(3), GA(8), GA(19) and GA(20) levels between embryo axes and cotyledons of dormant and no n-dormant beechnuts were detected with less pronounced differences for GA(4), GA(7) and GA(9) levels. Both the quantitative differences betw een dormant and non-dormant seeds in the analysed GAs corresponding to the 13-OH pathway, and the capacity of non-dormant seeds to carry out metabolic conversions when labelled GA(20) was injected into the seed s, reveal a dynamic role of GAs in dormancy release.