Auxins, biosynthesis

ZHAO, Y., CHRISTERSEN, S.K., FANKHAUSER, C., CASHMAN, J., COHEN, J., WEIGEL, D., CHORY, J., A role for flavin monooxygenase-like enzymes in auxin biosynthesis, Science, 2001, 291, 306-309. 

Ljung K, Bhalerao RP, Sandberg G. 2001. Sites and homeostatic control of auxin biosynthesis in Arabidopsis during vegetative growth. Plant J 28 465-474. 

KENDREW, S.G., YUCCA A flavin monooxygenase in auxin biosynthesis. Trends Biochem. Sci., 2001,26,218. 

All these compounds are intermediates in indole-3-acetic acid (auxin) biosynthesis of plants. They have been prepared on microscale341 with reasonably high yield, high purity... 

Standard microbial methods for investigating tryptophan biosynthesis were applied to plants in order to study auxin biosynthesis [6,212,218]. A series of Arabidopsis mutants with lesions in four sites in the pathway from chorismate to tryptophan has been obtained, but so far no comparable array of mutations exists for any other plant species [18]. Normanly et al. [44] used these Arabidopsis mutants to dissect lAA biosynthesis and showed that the non-tryptophan pathway to lAA branches from tryptophan biosynthesis at the point of indole or indole-3-glycerol phosphate. 

Zhao, Y., A.K. Hull, N.R. Gupta, K.A. Goss, J. Alonso, J.R. Ecker et al. (2002). Trp-dependent auxin biosynthesis in Arabidopsis involvement of cytochrome P450s CYP79B2 CYP79B3. Gen. Devel. 16, 3100-3112. 

EFFECTS OF PHENOUC COMPOUMDS ON AUXIN BIOSYNTHESIS AND VICE VERSA... 

Decades of studies have established that auxin biosynthesis is extremely complex and there are multiple Trp-dependent biosynthetic routes to lAA in plants [158], and microbes [159]. Microbial lAA biosynthesis pathways are well defined, but none of the proposed lAA biosynthetic pathways in plants has been completely defined. 

Direct measurements of lAA by RIA further support this view. Table 1 shows that levels of lAA and ACC in A. glutinosa and A. tabacum are affected similarly by tms genes. Thus differences in the capacity of these species to compensate for mutant tms genes do not result for differences in the accumulation of IA A, and some mechanism other than auxin biosynthesis appears to be involved. 

ABA inhibits the enhancement of elongation by auxin, and there is evidence that ABA can inhibit auxin biosynthesis. ABA appears to reduce lAA levels during the regeneration of a physiological tip in decapitated coleoptiles (Anker 1975), and there is evidence for ABA-enhanced auxin degradation in the presence of supraoptimal concentrations of lAA (Milborrow 1966). 

There is extensive evidence that GA increases auxin levels either by enhancement of auxin biosynthesis (Jindal and Hemberg 1976, Sastry and Muir 1965) or by retardation of auxin destruction (Kogl and Elema 1960). Nevertheless, there is convincing evidence that GA can also stimulate elongation independently of auxin (Kazama and Katsumi 1974, Cleland et al. 1968, Kaufman et al. 1969). In excised Avena stem internodes, for example, GA stimulates cell elongation, while auxin is inhibitory (Kaufman et al. 1969). Similarly, stimulation of lettuce hypocotyl elongation has been used as a bioassay for GA, while... 

One of the most potent factors in the regulation of lAA biosynthesis may be lAA itself. lAA appears to suppress its own biosynthesis in decapitated coleoptiles (Anker 1973), and certain auxin-induced modifications of growth patterns have been attributed in part to effects on endogenous auxin production (Evans and Schmitt 1975, Evans et al. 1977). Red light-induced suppression of auxin production in coleoptile tips may result from a suppression of auxin movement out of the tip leading to feedback inhibition of auxin biosynthesis (Huisinga 1976). 

Keywords ABA Auxin Biosynthesis Brassinosteroids Cytokinins Ethylene Gibberellins Jasmonates Salicylic acid Signaling Transcriptional factors... 

Korasick DA, Enders TA, Strader LC (2013) Auxin biosynthesis and storage forms. J Exp Bot 64 2541-2555... 

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