Gibberellin plant hormones

The gibberellin plant hormones continue to attract synthetic attention. The total synthesis of gibberellin A4 (101) by a more efficient route has been reported,176 and a major achievement has been the total synthesis of gibberellin Ax (102) and... 

Abscisin II is a plant hormone which accelerates (in interaction with other factors) the abscission of young fruit of cotton. It can accelerate leaf senescence and abscission, inhibit flowering, and induce dormancy. It has no activity as an auxin or a gibberellin but counteracts the action of these hormones. Abscisin II was isolated from the acid fraction of an acetone extract by chromatographic procedures guided by an abscission bioassay. Its structure was determined from elemental analysis, mass spectrum, and infrared, ultraviolet, and nuclear magnetic resonance spectra. Comparisons of these with relevant spectra of isophorone and sorbic acid derivatives confirmed that abscisin II is 3-methyl-5-(1-hydroxy-4-oxo-2, 6, 6-trimethyl-2-cyclohexen-l-yl)-c s, trans-2, 4-pen-tadienoic acid. This carbon skeleton is shown to be unique among the known sesquiterpenes. 

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. 

Riboflavin is produced by Clostridium, Ascomycetes and Candida species. The yield can be as high as 5 g 1 1 after 7 days 60). Gibberella fujikuroi is utilized for the synthesis of gibberellins, a group of plant hormones used for plant growth promotion. Glucose, molasses, lipid (corn oil) are usually used as carbon sources. Vitamin B12 may also be synthesized from alcohols and hydrocarbons. 

The history of gibberellin has been well described in the previous edition of the book Comprehensive Natural Products Chemistry,188 in other books, in a review,189-191 and on the website http //www.plant-hormones.info/ gibberellinhistory.htm and so is briefly reviewed in this chapter. 

V. M. Sponsel P. Hedden, In Plant Hormones Biosynthesis, Signal Transduction, Action Gibberellin Biosynthesis and Inactivation P. J. Davies, Ed. Kluwer Academic Dordrecht, 2004 pp 63-94. 

S. G. Thomas P. Hedden, Gibberellin Metabolism and Signal Transduction. In Plant Hormone Signaling S. G. Thomas,... 

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