Quantification of GA1, GA3, GA4, GA7, GA8, GA9, GA19 and GA20; and GA20 metabolism in dormant and non-dormant beechnuts

The endogenous levels of GA1, GA3, GA4, GA7, GA8, GA9, GA19 and GA20 were determined in beech seeds (Fagus sylvatica L.) treated with different dormancy breaking treatments. Gibberellins were analysed separately in cotyledons and embryo axes. After purification of the extracts, GAs were quantified by GC-MS-selected ion monitoring (GC-MS-SIM) with deuterated GAs as internal standards. The results showed that GAs corresponding to the 13-OH pathway seemed to be involved in dormancy breaking. Strong differences in GA1, GA3, GA8, GA19 and GA20 levels between embryo axes and cotyledons of dormant and non-dormant beechnuts were detected with less pronounced differences for GA4, GA7 and GA9 levels. Both the quantitative differences between 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 GA20 was injected into the seeds, reveal a dynamic role of GAs in dormancy release.