An extract from 6000 dark-grown Phaseolus coccineus seedlings was purified by countercurrent distribution and G-10 Sephadex followed by gradient elution from a silicic acid partition column with increasing amounts of ethyl actetate in n-hexane. 25 fractions were collected and tested with the barley-aleurone, ' lettuce, cucumber, maize, oat first-internode, and sugarcane-spindle bioassays. Major gibberellin(GA)-like activity was detected in fractions 4 (500~g GAs-equivalents ) and 12-13 (270ixg GAs-equivalents ) with smaller amounts in fractions 6, 8-9, 15-16, 18, 20, 23 and 25. The extracts were also applied to AMO-1618-dwarfed Ph.-coccineus seedlings. Fractions 4, 8 and 12 promoted the growth of both light-and dark-grown seedlings. GA 1, GAs, GA 4 and GA s were active in the Phaseolus bioassay but GAs-glucoside was inactive.
The biological and chromatographic properties of fractions 4, 8-9 and 12-13 correspond with those of GA4, GA19 and GA 1 . The identity of GA 4 in fraction 4 was conclusively established by combined gas chromatography-mass spectrometry (GC-MS) of the methyl ester and the trimethylsilyl ether of the methyl ester. Gasliquid-chromatography peaks corresponding to these derivatives of GA19 and GA s were detected on QF-1 and SE-33 columns but their intensities were too weak to permit conclusive identification by GC-MS.