Plant secondary metabolites biosynthesis

JulsingMK et al. (2006) Combinatorial biosynthesis of medicinal plant secondary metabolites. Biomol Eng 23(6) 265-279... 

Expressed sequence tag (EST) analysis of cDNAs from specific plant tissues has proved to be a valuable tool for the identification of genes for secondary metabolite biosynthesis.36 We have used this approach to identify two distinct sequences predicted to encode OSCs from cDNA libraries from roots of diploid oat (Avena strigosa).35 One of these sequences is highly homologous to cycloartenol... 

Recently, a new polyketide biosynthetic pathway in bacteria that parallels the well studied plant PKSs has been discovered that can assemble small aromatic metabolites.8,9 These type III PKSs10 are members of the chalcone synthase (CHS) and stilbene synthase (STS) family of PKSs previously thought to be restricted to plants.11 The best studied type III PKS is CHS. Physiologically, CHS catalyzes the biosynthesis of 4,2, 4, 6 -tetrahydroxychalcone (chalcone). Moreover, in some organisms CHS works in concert with chalcone reductase (CHR) to produce 4,2 ,4 -trihydroxychalcone (deoxychalcone) (Fig. 12.1). Both natural products constitute plant secondary metabolites that are used as precursors for the biosynthesis of anthocyanin pigments, anti-microbial phytoalexins, and chemical inducers of Rhizobium nodulation genes.12... 

Mahadevan reviewed research up to 1973, with respect to the pathways of oxime metabolism in plants, and evaluated a series of aliphatic and aromatic oximes that are precursors for the biosynthesis of plant secondary metabolites (as opposed to basic metabolism products that are essential for cell survival), such as cyanogenic glycosides, glucosinolates and certain phytohormones . Some of these oximes are shown below. 

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... 

In the plant, the biosynthesis of the Vinca alkaloids involves more than 20 enzymatic steps including several cytochrome P450 monooxygenases and one class III plant peroxidase. Removal of the toxic alkaloids from the cytoplasm to the vacuole of plant cells is made by an uncharacterised transport mechanism that we suggest may be an ABC transporter, as already shown for several other plant secondary metabolites. 

In plants, responses to many biotic and abiotic stresses are, at least in part, mediated by the jasmonate family, including jasmonate (JA) and its methyl ester MeJA, which are synthesized via the octadecanoid pathway, beginning with phospholipase A to release linolenic acid from chloroplast membrane [27,28]. They play a central role in regulating the biosynthesis of many secondary metabolites, and induction of plant secondary metabolite accumulation by the JA family is not limited to certain types of metabolites in most plants [29], as shown in Table 17.1. 

Plant secondary metabolites are biosynthesized from rather simple building blocks supplied by primary metabolism. Two important metabolic routes in this are the shikimate pathway and the isoprenoid biosynthesis. The shikimate pathway leads to the synthesis of phenolic compounds and the aromatic amino acids phenylalanine, tyrosine and tryptophan. The isoprenoid biosjmthesis is a heavily branched pathway leading to a broad spectrum of compounds (fig. 1). From plants and microorganisms more than 37,000 isoprenoid compounds have been isolated so far [1]. 

Hahlbrock K, Scheel D (1989) Physiology and molecular biology of phenylpropanoid metabolism. Annu Rev Plant Physiol Plant Mol Biol 40 347-369 Hasegawa S, Herman Z (1992) Biosynthesis of limonoids in Citrus. In Petroski RJ, McCormick SP (eds) Secondary-metabolite biosynthesis and metabolism. Plenum Press, New York, pp 305-317... 

Almagro L, Sabater-Jara AB, Belchi-Navatro S, Femandez-Perez F, Bru R, Pedreno MA (2011) Effect of UV light on secondary metabolite biosynthesis in plant cell cultures elicited with cyclodextrins and methyljasmonate. Plants and environment, 1st edn. Intech, Croatia... 

As described above, Ja and MeJa act as key compounds of the signal transduction pathway involved in the induction of the secondary metabolite biosynthesis which takes part in plant defense reactions [56, 57]. Thus, the production of secondary metabolites increases when plant cell cultures are elicited with jasmonates [36, 49, 58]. In Vitis, trans-R and stilbene-related production is increased by adding Ja or MeJa [30, 54]. In this respect, Tassoni et al. [54] showed that the addition of 10 pM MeJa was more effective in stimulating endogenous accumulation (24 pg g ... 

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