Gibberellic acid biosynthesis

BR biosynthesis inhibitors are potentially valuable tools for studying BR biosynthesis (Asami and Yoshida, 1999). Triazoles are known BR biosynthesis inhibitors however, they are not very specific and also suppress the synthesis of gibberellic acid (Rademacher, 2000) or cardenolides (see above). A more specific BR biosynthesis inhibitor, brassinazole, was synthesized by modifying uniconazole (Min et al., 1999). Treatment of Arabidopsis seedlings with brassinazole resulted in a phenotype typical of BR-deficient mutants (Asami... 

Terpenoids, which are also known as isoprenoids, constitute the most abundant and structurally diverse group of plant secondary metabolites, consisting of more than 40,000 different chemical structures. The isoprenoid biosynthetic pathway generates both primary and secondary metabolites that are of great importance to plant growth and survival. Among the primary metabolites produced by this pathway are phytohormones, such as gibberellic acid (GA), abscisic acid (ABA), and cytokinins the carotenoids, such as chlorophylls and plastoquinones involved in photosynthesis the ubiquinones required for respiration and the sterols that influence membrane stmcture (see also Steroid and Triterpene Biosynthesis) (Fig. 1). Monoterpenoids (CIO), sesquiterpenoids (Cl5), diterpenoids (C20), and... 

Hydroxy-(—)-kaur-16-en-19-oic acid and 6j ,7 -dihydroxy-( —)-kaur-16-en-19-oic acid have been prepared for investigation into the biosynthesis of gibberellic acid, the former by Meerwein-Ponndorf reduction of the 7-ketone and the latter by osmylation of a 6,7-olefin. 

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.

The plant hormone gibberellic acid (D 6.3 a nonsubstrate-like signal), for instance, reduces the biosynthesis of amaranthine, a betalain (D 22.1.4), by limitation of precursor supply, an effect normalized by the administration of L-tyrosine or l-DOPA,... 

Cofactor of ethylene biosynthesis in cauliflower florets Synergist of gibberellic acid in Lactuca and some other plants... 

The gibberellic acid-induced biosynthesis and release of cell-wall degrading e/jrfo-D-xylanase by isolated aleurone layers of barley have been studied. Studies on the D-xylanase system of Streptomyces species have included a study of the action of the enzyme on various o-xylans and D-xylo-oligosaccharides. The isolation and structural identification of arabino-D-xylo-oligosaccharides arising from action of the enzyme on corn cob arabino-D-xylan were reported. Mutant strains of Trichoderma viride not producing D-xylanase have been induced and isolated with the aid of nystatin selection. ... 

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