Biolog-ical Evaluation of Gibberellins 



515 



HO 



COMPOUND 



BIOLOGICAL ASSAY 



BEAN EPICOTYL TOMATO OVARY 

 ELONGATION GROWTH 



Active 



Active 



n 



^^3 " COOH 



= 



HOOC 



m 



12 



CHa 



Not 

 Active 



Not 

 Active 



Fig. 7. Relative activity of gibberellin A3 derivatives in elongation of the bean 

 epicotyl and growth of tomato ovaries. 



lactone group on ring A was removed, and compound V, in which 

 the lactone group was removed and the product decarboxylated, were 

 not active. The Wagner-Meerwein derivative of A3 (Figure 7, II) 

 was slightly active (less than 20 per cent of Ao), while products III 

 and IV (fl//ogibberic acid) were not active. Dihydro-gibberellin A4 

 (Figure 8, II) was about 50 per cent as active as A4. When the D rmg 



