Gibberellin biosynthesis inhibitor

Kim, H. Y., and Suzuki, Y. (1989). Changes in assimilated BC distribution and soluble acid invertase activity of Zinnia elegans induced by Uniconazol an inhibitor of gibberellin biosynthesis. Plant Physiol. 90, 316-321. 

Plant hormone biosynthesis and metabolism are influenced and modified, too, as already mentioned, by a large number of typical secondary plant constituents of quite different structures (Eef. 5, 6). For instance, it has been shown that some oi-disubstituted acetic acid derivatives are active both as antiauxins and as inhibitors of the biosynthesis of cyclic terpenoids. Thus, some more simple model compounds synthesized by ourselves, for example substituted a-phenoxy-isobutyrio acids, are not only competitive auxin inhibitors but they are also able to inhibit both the gibberellin and sterol biosynthesis. The same is true for some well known plant growth retardants, such as CCO or AMO 1618, which are inhibitors of gibberellin biosynthesis both in plants and in Fus ium moniliforme, but at the same time they are inhibiting and modifying also the biosynthesis of steroids in the respective organisms as well as in animal in vitro systems (Eef. 29) ... 

Lang, The plant growth retardant CCC as inhibitor of gibberellin biosynthesis in Fusarium moniliforme, PIanta 61, 229 (1964). 

In their efforts to study the mechanism of terpene synthases, Coates and coworkers synthesized aza derivatives of ent-kaurene. The two heterocyclic analogs, 16-aza-trachylobane (107) and 16-aza-beyerane (108), were synthesized froment-beyeran-16-one (103), which was obtained from the natural product stevioside (102, Scheme 5.24T These analogs were assessed for their utility as active site probes for various ent-diterpene cyclases and as selective inhibitors of gibberellin biosynthesis in plants. 

Several triazole and pyrimidine ergosterol biosynthesis inhibitors (see section 5.4.5.5) also inhibit gibberellin synthesis, and therefore act as plant growth retardants, e.g. Paclobutrazol. 

In a wide spectrum of plant species and organs, gibberellin-induced cell elongation has been correlated with a predominance of transverse CMTs [15,83,111,113-118]. Conversely, when endogenous levels of gibberellins became depleted by means of specific inhibitors of their biosynthesis (e.g., ancymidol, 25,35 paclobutrazol), the CMTs then... 

Fig. 3. Impaired arrangements of CMT arrays in cells of gibberellin (GA)-deficient mutant (d5) maize roots (a,b) and in cells of cv. LG-11 maize roots treated with inhibitor of GA biosynthesis 2S, 3S paclobutrazol (e,f). For more details on these treatments see [119]. Note that CMT arrays show abundant holes in the GA-deficient root cells (arrows). Addition of exogenous gibberellic acid rescues these lesions and well ordered transverse CMT arrays appear in cells of both d5 mutants (c,d) as well as of paclobutrazol-treated LG-11 root cells (g, h). Bar represents 10 pm.

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