Of gibberellins

KOOKNNEEF, M., VAN DER VEEN, J.H., Induction and analysis of gibberellin sensitive mutants in Arabidopsis thaliana (L.) Heynh, Theor. Appl. Genet., 1980, 58, 257-263. 

Faull, K. R., B. G. Coombe, and L. G. Paleg. Extraction and characterization of gibberellins from Hordeum vulgare seedlings. Aust J Plant Physiol 1974 1 183. 

Haddon, and M. M. Fitch. Identification of gibberellins from sugar cane SO 102 plants. ] Plant Growth Regul 1983 ... 

In continuation of previous work, the reactions of gibberellin A, and Aj with neutral manganese dioxide have been examined. The products include those of decarboxylation and of lactonization on to C-15. The full paper describing the interesting bridgehead C-13 fluorination of gibberellins with fluoramine has appeared. ... 

A number of papers on the biological activity of gibberellins and their derivatives have appeared. The stimulation of plant mRNA synthesis by gibberellic acid has been noted. 

Figure 2 (adapted after 13) shows that the increased concentration of gibberellin solutions applied at weekly intervals to apples produced a reduction in the concentration of total nitrogen and sugars with a consequent decline in mite populations. 

Figure 2. Effect of weekly sprays of gibberellin solutions on nitrogen ( J and total sugar ( ) concentration in apple leaves and consequent effect on mite progeny production (M) (13).

The most commercially successful PGRs are those that operate either through the inhibition of gibberellin biosynthesis, from mevalonic acid (Knee, 1982) or through the production of ethylene. These represent the two most valuable pathways for growth modification since they have key roles in extension growth, ripening, fruit set and dominance. 

They act by altering the endogenous balance of gibberellins (inhibition) and ethylene (enhancement) and are often used in mixtures. Thus, ethephon, an ethylene generator, is applied in combination with mepi-... 

Rearrangement of gibberellin Ax (IV) to the ketone (V) and oxidation of the latter gave a diketone (VI) which, on dehydrogenation gave 1,7-dimethyl-fluoren-2-ol (VII) whose structure was established by synthesis (13). 

Isolation and Structures of Gibberellins from Higher Plants... 

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