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.