Terpenoids accumulation

Martin D., Tholl D., Gershenzon J. and Bohlmann J. (2002) Methyl jasmonate induces traumatic resin ducts, terpenoid resin biosynthesis and terpenoid accumulation in developing xylem of Norway spruce stems. Plant Physiol. 129, 100-1018. 

GERSHENZON, J., The metabolic costs of terpenoid accumulation in higher plants., J. Chem. Ecol, 1994, 20, 1281-1328. 

This correlative analysis of terpenoid accumulation, TPS enzyme activities, and functional characterization of a family of cloned TPS genes in Norway spruce and Sitka spruce in response to MeJA treatment and insect attack will guide future studies regarding differential expression of TPS genes in conifer defense, including in situ localization of gene expression and TPS enzymes. 

J. Varns, J. Ku and E. Williams, "Terpenoid Accumulation as a Biochemical Response of the Potato Tuber to Phytophthora infestans". Phytopathology. 61. 174-177 (1971). 

The early literature on monoterpene biotransformation was highly influenced by the approach used in steroid biotransformations and mainly focused on terpenoids accumulated by fungal strains which do not mineralize the substrate but partly oxidize it by fortuitous cometabolism. These studies often resulted in the accumulation of a mixture of different products in low yields and at low concentrations [1]. Several bacteria which completely mineralize monoterpenes have been described more recently. It has become obvious from the later studies that multiple pathways are involved in the degradation of monoterpenes in many of these microorganisms, and consequently it has been difficult to obtain mutants allowing the accumulation of partially oxidized products. 

Opitz S, Kunert G, Gershenzon J (2008) Increased terpenoid accumulation in cotton (Gossypium hirsutum) foliage is a general wound response. J Chtan Ecol 34 508-522. doi 10.1007/sl0886-008-9453-z... 

Another example of successful engineering of terpene biosynthesis is the constitutive overexpression of the gene encoding the first-step enzyme 1-deoxy-D-xylulose-5-phosphate synthase (DXPS) in the DXP pathway in bacteria and Arabidopsis. In both cases, increased enzyme activity caused increased accumulation of downstream terpenoids, suggesting that DXPS is rate-limiting [8]. 

Exposure of rat primary mixed hippocampal cell cultures to either sodium nitroprusside (SNP 100 xM) or 3-morpholinosydnonimine resulted in both a decrease in cell survival and an increase in free-radical accumulation. These SNP-induced events were blocked by either EGb 761 (10 to 100 pg/ml) or its flavonoid fraction CP 205 (25 pg/ml), as well as by inhibitors of protein kinase C (PKC chelerythrine) and 1-type calcium channels (nitrendipine). In contrast, the terpenoid constituents of EGb 761, known as bilobalide and ginkgolide B, as well as inhibitors of phospholipases A [3-[4-octadecyl)benzoyl]acrylic acid (OBAA)] and C (U-73122), failed to display any significant effects. Moreover, EGb 761 (50 pg/ml), CP 205 (25 pg/ml), and chelerythrine were also able to rescue hippocampal cells preexposed to SNP (up to 1 mM). Finally, EGb 761 (100 g/ml) was shown to block the activation of PKC induced by SNP (100 xM). These data suggest that the protective and rescuing abilities of EGb 761 are not only attributable to the antioxidant properties of its flavonoid constituents but also by their ability to inhibit NO-stimulated PKC activity (Figure 36.1). 

Cathenamine (100) has been identified as an early intermediate in terpenoid indole alkaloid biosynthesis (cf. Vol. 8, p. 27). It has also been isolated from Guettarda eximia. Another alkaloid, 4,21-dehydrogeissoschizine (99), has now been isolated from this plant it is readily converted into (100) in alkaline solution.29 On incubation with an enzyme preparation from Catharanthus roseus cell cultures in the presence of NADPH at pH 7, (99) was converted into ajmalicine (102), 19-ep/-ajmalicine (103), and tetrahydroalstonine (104), which are the normal products with this enzyme preparation. In the absence of NADPH, cathenamine (100) accumulated.30 The reaction to give (100) proceeded linearly with time, and was dependent on the concentration of protein and substrate. No conversion occurred in the absence of enzyme. 

Secondary metabolites include essential oils, used in the flavour and fragrance industries. Essential oils are found in over 50 plant families and represent terpenoids and other aromatic compounds accumulating typically at relatively low concentrations (usually <1% of fresh weight, but can be up to 20%), but which have useful antimicrobial activity (Biavati el a/., 2003). Production of essential oils by plants is affected by many factors influencing plant growth. 

The content of extractives and their composition vary greatly among different wood species and also within the different parts of the same tree (cf. Appendix). Wood extractives can be divided into three subgroups aliphatic compounds (mainly fats and waxes), terpenes and terpenoids, and phenolic compounds. Parenchyma resin is rich in aliphatic components and the oleoresin is mainly composed of terpenoids. Characteristic of the heartwood is the accumulation of phenolic compounds. 

When plants undergo various stresses, certain secondary metabolites, including defense compounds, accumulate. Several secondary metabolites such as terpenoid indole alkaloids, indole glucosinolate, nicotine alkaloids, and polyamines are known to accumulate through the induction of biosynthetic genes by jasmonates.898-900 MeJA also induces genes involved in the formation of tryptophan derivatives, terpenoid indole alkaloids.901 These compounds are known to be involved in defense response to pathogen attack as phytoalexins. 

Males of neotropical euglossine bees (Apidae), called orchid bees, collect odoriferous substances from flowers of orchids and other plants. The floral scents of these species display relatively simple chemical compositions dominated by one or two major components, mostly terpenoids and aromatic compounds such as cr-pinene, 1,8-cineol, eugenol, -dimethoxybenzene (35), 2,3-epoxygeranyl acetate (36), nerolidol, 4-methoxycinnamaldehyde (37), and benzyl benzoate.113 Since the orchid bees have odor preferences, their collection of fragrances leads to specialized pollination of particular plant species. Male bees absorb the floral volatiles with their tarsal hairs, form species-specific bouquets, and finally accumulate them in their hind tibial pouches. These bouquets have potential roles in courtship displays and marking territories.114 115... 

There have been a number of previous reviews on microbial oxidations of teipenes. Monoter-penes are often degraded progressively after an initial hydroxylation step, but di-, tri- and sesqui-tetpenes can be converted more selectively, to accumulate useful quantities of hydroxyla products. Less systematic work on the microbial oxidation of terpenoids has l n carried out than in the case of steroids, and therefore prediction of the regio- and stereo-chemistry is scarcely possible. 

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