Hormone gibberellic acid

Identify compounds A and B, two synthetic intermediates in the 1979 synthesis of the plant growth hormone gibberellic acid by Corey and Smith. Gibberellic acid induces cell division and elongation, thus making plants tall and leaves large. 

These are early steps in Corey s synthesis of the plant hormone gibberellic acid (E. J. Corey and group, J. Am. Chem. Soc., 1978, 100, 8031-6). 

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,... 

Dihydroconiferylalcohol acts synergistically to the plant hormone gibberellic acid (E 2.2). 

Kaufman suggested (97d) that silica polymerization is inhibited in regions where the hormone gibberellic acid causes a lowering of the pH from 6.5 to 5.0 or less, as noted in elongating cells, for example (97e). It may be significant that such a drop in pH would stabilize the tropolone-type chelates of silicon and thus inhibit release of monomer (see Weiss, in Ref. 127). 

Plant hormones abscisic acid and gibberellic acid... 

It is now supposed that gibberellic acid stimulates the hormonal production of a-amylase (and, probably, of /9-amylase and others) in the aleurone layer surrounding the endosperm starch-reserve. Gibberellic acid released 400 mg. equivalents of D-glucose per g. in 90 hours in wheat grains, with a maximum hydrolytic activity after 60 hours. The effect on /9-amylase was thought to be a release (to the extent of 85%) from the protein-bound, insoluble form.876... 

The ability to synthesize diterpenes is universal to plants, since phytol, the acyclic parent compound of the series, is present in ester attachment in the chlorophyll molecule and hence occurs in all green plants. Gibberellic acid is also widespread in the plant kingdom as a growth hormone. Besides phytol and gibberellic acid, the remaining diterpenoids are very restricted in occurrence and usually occur within one or only a few plant... 

These compounds were originally isolated from a parasitic fungus that causes excessive leaf elongation in nee plants. The mechanisms and applications of this group of compounds are described in Gibberellic Acid and Gibberellin Plant Growth Hormones. 

PLANT HORMONES (Gibberellins). See Gibberellic Acid and Gibberellin Plant Growth Hormones. 

The most promising leads have come from studying the hormonal requirements of the system. By themselves, we can find no indication whatsoever of any growth promotion by any of the alkyl lipides. When gibberellic acid is also applied, response remains small. If indoleacetic acid, or another auxin, is added, the sections show the classic bioassay response—and this is further stimulated by the active lipides. In the presence of both auxin and gibberellic acid, however, the sections show their greatest capacity to elongate still further in the presence of the alkyl lipides (I). Remarkably, the lipides are most effective at concentrations corn-... 

Chrispeels, M. J. Varner, J. E. Hormonal control of enzyme synthesis On the mode of action of gibberellic acid and abscisin in aleurone layers of barley. Plant Physiol., 1967, 42(7), 1008-1016. 

With the exception of 2,4-D and gibberellic acid treatments of a variety of citrus crops, where improved fruit set, reduced fruit drop, and the ability to delay harvesting without loss of fruit quality are recognized benefits, few applications have been developed for the use of hormone-type regulators in tropical fruits. Recent work has shown that gibberellic acid will delay postharvest ripenining and improve the quality of bananas and that napthaleneacetic acid treatment of oil palm to delay fruit abscission has increased both yield and oil content. 

Important biological compounds that are derivatives of diterpenes include gibberellic acid, which is a plant growth hormone. 

---