The biological activities of 26 gibberellins in nine plant bioassays

Abstract

The activities of gibberellins A 1 –A 15 , A 17 –A 27 and A 8 -glucoside are compared, using original and previously published data, in the barley (Hordeum vulgare L.) aleurone α-amylase, Progress No. 9 dwarf pea (Pisum sativum L.), lettuce (Lactuca sativa L.), 'Tan-ginbozu' dwarf rice (Oryza sativa L.), cucumber (Cucumis sativus L.), and the d-1, d-2, d-3, and d-5 maize (Zea mays L.) mutant bioassays. Gibberellins A 3 and A 7 show high activity in most bioassays. Gibberellins A 9 , A 10 , A 23 , and A 24 are species specific in their activity. Gibberellins A 8 , A 11 , A 12 , A 13 , A 14 , A 17 , A 25 , A 27 , and A 8 -glucoside exhibit low activity. Gibberellin A 26 is inactive up to 10 0 μg in all assays. The cucumber hypocotyl and barley aleurone bioassays respond only to a narrow spectrum of gibberellins while the rice bioassay is sensitive to all the gibberellins except A 21 , A 25 , and A 26 .Activity in the cucumber assay is restricted to gibberellins with a 13-deoxylactonic structure. With the exception of gibberellins A 8 , A 26 , and A 27 , only gibberellins having either an oxygenated C-3 position or a C-2,3 double bond, and a 19,10-lactone function, show more than low activity in the barley aleurone assay. Hydroxylation at the C-2 position may account for the reduced activity of gibberellins A 8 , A 26 , and A 27 . Possible reasons for a lack of correlation between gibberellin structure and biological activity in other bioassays are discussed.