Endogenous Gibberellins in Elongating Shoots of Clones of Salix dasyclados and Salix viminalis

Elongating shoots of rapidly growing clones of Salix viminalis L. (clone 683-4) and Salix dasyclados Wimm. (clone 908) harvested in early August were analyzed for endogenous gibberellins (GA). Distribution of GA-like activity, determined by Tan-ginbozu dwarf rice microdrop bioassay after reverse phase C(18) high performance chromatography, was similar for both species. For S. dasyclados, combined gas chromatography-selected ion monotoring (GC-SIM) yielded identifications of GA(1), GA(8), GA(19), GA(20), and GA(29). Identifications of GA(4) and GA(9) were also made using co-injections of known amounts of [17, 17-(2)H(2)]GAs. By bioassay, the main activity was GA(19)-like in both species. Gibberellin A(1), GA(19), and GA(20) concentrations were approximated by GC-SIM using co-injections of known amounts of [17,17-(2)H(2)]GAs. Both bioassay and GC-SIM results indicated very high concentrations of GA(19) and GA(20) (about 6000 nanograms per kilogram fresh weight shoot tissue using GC-SIM: 800 ng using bioassay), compared to the concentration of GA(1) (about 130 nanograms per kilogram fresh weight using either GC-SIM or bioassay).