Quantification of GA1, GA3, GA4, GA7, GA9, and GA20 in vegetative and male cone buds from juvenile and mature trees of Pinus radiata

The gibberellins GA(1), GA(3), GA(4), GA(7), GA(9) and GA(20) were quantified in vegetative and pollen cone buds of juvenile and mature trees of Pinus radiata by combined gas chromatography-mass spectrometry and selected ion monitoring (GC-MS-SIM) using deuterated GAs as internal standards. Higher levels of GA(7) and GA(9) and lower levels of GA(4) were detected in juvenile vegetative buds compared to mature buds, and there were no differences in relation to age for GA(1), GA(3) and GA(20). Conversely, when differences between vegetative and pollen cone buds from a mature tree were studied, the highest levels of GA(1) and GA(4) were found in pollen cone buds, similar levels of GA(3), GA(7) and GA(9) were observed in both, and ten fold lower levels of GA(20) were found in pollen cone buds as compared with vegetative buds. These results indicate a difference in GA metabolism in relation to both the tree age as well as the physiological status of buds: vegetative or reproductive in this conifer.