Sesquiterpenoid phytoalexins

Hammerschmidt, and R. Bostock. Accumulation of six sesquiterpenoid phytoalexins in tobacco leaves infiltrated with Pseudomonas lachrymans. Phytochemistry 1982 21(12) 2987-2988. 

NT457 Wibberley, M. S., J. R. Lenton, and S. NT469 J. Neill. Sesquiterpenoid phytoalexins produced by hairy roots of Nicotiana tabacum. Phytochemistry 1994 37(2) ... 

F. Ewing. 5-Epi-aristolochene is a common precursor of the sesquiterpenoid phytoalexins capsidiol and debneyol. Phytochemistry 1989 28(3) 775-779. Borys, D. J., S. C. Setzer, L. J. Ling. CNS depression in an infant after the ingestion of tobacco A case report. Vet Hum Toxicol 1988 30(1) 20-22. Deutsch, H. M., K. Green, and L. H. Zalkow. Water soluble high molecular weight components from plants with potent intraocular pressure lowering activity. Curr Eye Res 1987 6(7) 949-950. 

R. Threlfall. Sesquiterpenoids related to the phytoalexin debneyol from elicited cell suspension cultures of Nicoti- NT613 ana tabacum. Phytochemistry 1988 ... 

Murai, A., Abiko, A., Ono, M., and Masamune, T. (1982) Synthesis of aubergenone, a sesquiterpenoid phytoalexin from diseased eggplants. Bulletin ofthe Chemical Society of Japan, 55, 1191-1194. 

Whitehead, I.M., Threlfall, D.R., Ewing, D.F., 5-epi-aristolochene is a common precursor of the sesquiterpenoid phytoalexins capsidiol and debneyol, Phytochemistry, 1989,28,775-779. 

In Gossypium spp. (Malvaceae), sesquiterpenoid phytoalexins identified so far are cadinene derivatives that are biosynthesized from -cadinene.241 CAD1-A and CAD1-C were functionally identified as sesquiterpene cyclases that catalyze the conversion of farnesyl diphosphate into -cadinene (Figure 23). GaWRKY 1 is a... 

Figure 23 Putative biosynthetic pathway of a sesquiterpenoid phytoalexin, gossypol.

Lubimin, a phytoalexin found in several Solanaceae, has been assigned the spiro-structure (57) on n.m.r. and biosynthetic evidence,83 whilst the new sesquiterpenoid skeleton of taylorione (58) from the liverwort Mylia taylorii is thought84 to be biosynthesized via an aromadendrene-type precursor which may also generate the co-occurring myliol (59). 

Direct-defense compounds can be either constitutively present in (specific parts of) the plant or be produced after induction by pathogens or herbivores. The latter compound will be less costly for the plant. For example, elicitor-induced accumulation of the antimicrobial sesquiterpenoid capsidiol correlated with the induction of 5-ept-aristolochene synthase, which is a branch-point sesquiterpene cyclase involved in the synthesis of sesquiterpene phytoalexins (8). In rice Oryza saliva L.), 14 diterpenoid phytoalexins have been identified. All these compounds are accumulated in rice leaves after inoculation with the... 

As far as we know, only one report on this enzyme from plants is available showing a light induction of the enzyme after wounding or elicitation [294]. In addition to essential constitutive metabolites. Solarium tuberosum synthesizes antifungal sesquiterpenoid phytoalexins in response to fungal infection or arachidonic acid... 

An investigation of the metabolism of sesquiterpenoid phytoalexins has shown that pepper or potato cell cultures can convert capsidiol (485) and rishitin (450) into their 13-hydroxy-derivatives cf. p. 136). Solavetivane derivatives of this type have previously been isolated from flue-cured tobacco (Vol. 8, p. 107). New chemical and spectroscopic evidence has led to a revised configuration for the 3-hydroxy- or 3-acyloxy-substituent in furanofukinol (486) (Petasites japonica Maxim.) and the related esters (487) and (488), previously isolated from Farfugium hiberniflorum Kitam. ... 

Takasugi and collaborators85 have reported the isolation of a sesquiterpenoid phytoalexin, cichoralexin (154) from Cichorium intybus inoculated with Pseudomonas cichorii. Its structure was elucidated by spectroscopic methods. 

Structure Revision and Blogenetlc Relationship of Aubergenone, a Sesquiterpenoid Phytoalexin of Eggplants", Chem. Lett., 1209-1212 (1978). (b) A. Mural, A. Abiko, M. 

Ono, and T. Masamune, "Synthesis of Aubergenone, a Sesquiterpenoid Phytoalexin from Diseased Eggplants",... 

Postinfectional Inhibitors from Plants. XXIII. Sesquiterpenoid Phytoalexins from Fruit Capsules of Datura stramonium". Can. J. Bot., 54, 25-29 (1976). 

I. Ito, N. Kato, and I. Uritani, "Biochemistry of Two New Sesquiterpenoid Phytoalexins from Sweet Potato Roots", Agric. Biol. Chem., Wl), 159-164 (1984) and references therein. 

On the other hand. Furze et al. [78] observed that using abiotic compounds on D. stramonium hairy roots the sesquiterpenoid phytoalexin production was elicitated but no response was observed on tropane alkaloids production [78], Also, Pitta-Alvarez et al. [42, 45] reported that B. Candida hairy roots responded positively to different elicitors. Among them it can be mentioned chitosan, acetic acid and citric acid. These compounds promoted the release of alkaloids to the culture medium [42],... 

Furze, J. M., Rhodes, M. J. C., Parr, A. J., Robins, R. J., Withehead, I. M., and Threlfall, D. R. (1991) Abiotic factors elicit sesquiterpenoid phytoalexin production but not alkaloid production in transformed root cultures of Datura stramonium. Plant Cell Reports. 10, 111-114. 

Phytoalexins from many different plants have been chemically characterized. The phytoalexins include isoflavanoid-derived pterocarpan compounds characteristic of the Leguminosae, sesquiterpenoid compounds characteristic of the Solanaceae, phenanthrene compounds characteristic of the Orchidaceae and acetylenic compounds characteristic of the Compositae. 

A number of sesquiterpenoid phytoalexins related to gos-sypol (29, Fig. 21.14) have been isolated from members of the genus Gossypium (Malvaceae) (Coxon, 1982 Gershen-zon and Croteau, 1991). These compounds inhibit germination of conidia of the fungus responsible for verticillium wilt in cotton at levels well below that of fungicidal activity (Mace et al., 1985). The principal phytoalexin produced is hemigossypol (39) (Brooks and Watson, 1985). 

Mevinolin has been described [1] as a potent and specific inhibitor of the enzyme 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase which catalyzes the formation of MVA, the first committed step in isoprenoid biosynthesis. Assuming that ABA is synthesized from a larger precursor, one would expect mevinolin to be without effect on short-term ABA biosynthesis. However, as shown in Table 1, mevinolin strongly inhibited ABA accumulation in water-stressed Xanthium leaves, 50% inhibition being caused by approximately 0.4 mM mevinolin. Attempts to reverse the inhibition with prior or simultaneous MVA applications failed (Table 2). This indicates that HMG-CoA reductase is not the critical step in ABA biosynthesis that is blocked by mevinolin. It must be assumed, therefore, that mevinolin inhibits other reactions in the ABA biosynthetic pathway. Although reversal of mevinolin inhibition of growth by MVA has been observed in plants [3], failure to obtain reversal has been observed with the accumulation of sesquiterpenoid phytoalexins in potato [21] and tobacco [6]. 

Mono- and sesquiterpenes are the main constituents of the essential oils, while the other terpenes are constituents of balsams, resins, waxes, and rubber. Oleoresin is a roughly equal mixture of turpentine (85 % Cio-monoterpenes and 15 % C15- sesquiterpenes) and rosin (C2o-diterpene) that acts in many conifer species as a toxic material to invading insects and their pathogenic fungi [12]. A number of angiosperm species have inducible terpenoid defensive compounds (phytoalexins) [13]. These include both sesquiterpenoid and diterpenoid t)pes. Isoprenoid units are also found within the framework of other natural molecules. Thus, indole alkaloids, several quinones (vitamin K), alcohols (vitamin E, vitamin A formed from p-carotene), phenols, and isoprenoid alcohols (also known as terpenols or polyprenols) also contain terpenoid fragments. The biogenesis. 

Watson DG, Rycroft DS, Freer IM, Brooks CJW (1985) Sesquiterpenoid phytoalexins from suspended callus cultures of Nicotiana tabacum. Phytochtarristry 24 2195—2200... 

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