Two Classes of Plant Antibiotics: Phytoalexins versus "Phytoanticipins"

VanEtten, Hans D.; Mansfıeld, John W.; Bailey, John; Farmer, Edward E.

doi:10.2307/3869817

Cited by 328 publications

(231 citation statements)

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“…Several alternatives have been proposed, including the existence of both tryptophan-dependent and tryptophanindependent pathways in A. thaliana (44)(45)(46)(47). Furthermore, although indolic glucosinolates were not among the major substances identified under the present conditions, they are known to be derived from tryptophan and believed to act as phytoanticipins in pathogen defense (26,27,48,49). Thus they may constitute a relatively low-abundance or otherwise undetected group of compounds.…”

Section: Discussionmentioning

confidence: 90%

“…However, indolic metabolism in Brassicaceae is very complex and includes numerous functionally distinct classes of compounds, including the phytohormone auxin (indole-3-acetic acid; ref. 44) and the herbivore, and possibly pathogen, defense-related indolic glucosinolates (26,27). None of the respective biosynthetic pathways, nor their interdependence, have been fully elucidated.…”

Section: Discussionmentioning

confidence: 99%

“…thaliana is a member of the Brassicaceae family, which is known for the frequent occurrence of various indolic constituents, including several indolyl glucosinolates and closely related indolyl thiazoles, including camalexin and 6-methoxycamalexin (25,26). Both camalexin and 6-methoxycamalexin have antibiotic activity and are induced upon infection and hence are considered to act as phytoalexins (27). In A. thaliana, camalexin, but not 6-methoxycamalexin, has been shown to accumulate in response to infections and to fulfill all of the criteria of a bona fide phytoalexin.…”

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confidence: 99%

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Accumulation of soluble and wall-bound indolic metabolites in Arabidopsis thaliana leaves infected with virulent or avirulent Pseudomonas syringae pathovar tomato strains

Hagemeier¹

2001

Proceedings of the National Academy of Sciences

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The chemical structures and accumulation kinetics of several major soluble as well as wall-bound, alkali-hydrolyzable compounds induced upon infection of Arabidopsis thaliana leaves with Pseudomonas syringae pathovar tomato were established. All identified accumulating products were structurally related to tryptophan. Most prominent among the soluble substances were tryptophan, ␤-D-glucopyranosyl indole-3-carboxylic acid, 6-hydroxyindole-3-carboxylic acid 6-O-␤-D-glucopyranoside, and the indolic phytoalexin camalexin. The single major accumulating wall component detectable under these conditions was indole-3-carboxylic acid. All of these compounds increased more rapidly, and camalexin as well as indole-3-carboxylic acid reached much higher levels, in the incompatible than in the compatible P. syringae͞A. thaliana interaction. The only three prominent phenylpropanoid derivatives present in the soluble extract behaved differently. Two kaempferol glycosides remained largely unaffected, and sinapoyl malate decreased strongly upon bacterial infection with a time course inversely correlated with that of the accumulating tryptophan-related products. The accumulation patterns of both soluble and wallbound compounds, as well as the disease resistance phenotypes, were essentially the same for infected wild-type and tt4 (no kaempferol glycosides) or fah1 (no sinapoyl malate) mutant plants. Largely different product combinations accumulated in wounded or senescing A. thaliana leaves. It seems unlikely that any one of the infection-induced compounds identified so far has a decisive role in the resistance response to P. syringae.

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Section: Discussionmentioning

confidence: 90%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Accumulation of soluble and wall-bound indolic metabolites in Arabidopsis thaliana leaves infected with virulent or avirulent Pseudomonas syringae pathovar tomato strains

Hagemeier¹

2001

Proceedings of the National Academy of Sciences

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“…When plants are attacked by pathogenic microorganisms, they respond by a variety of defense reactions, including production of phytoalexins that are low-molecular weight compounds serving as plant antibiotics [1,2]. Four structurally distinct types of polycyclic diterpenoid phytoalexins, oryzalexins A-F [3][4][5], ())-phytocassanes A-E [6][7][8], momilactones A and B [9,10], and oryzalexin S [11], have been identified in extracts of the leaves of rice plants that were either infected with the rice leaf blast pathogen, Magnaporthe grisea, or exposed to ultra-violet (UV)-irradiation.…”

Section: Introductionmentioning

confidence: 99%

Stemar‐13‐ene synthase, a diterpene cyclase involved in the biosynthesis of the phytoalexin oryzalexin S in rice

et al. 2004

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In suspension-cultured rice cells, diterpenoid phytoalexins are produced in response to exogenously applied elicitors. We isolated a cDNA encoding a diterpene cyclase, OsDTC2, from suspension-cultured rice cells treated with a chitin elicitor. The OsDTC2 cDNA was overexpressed in Escherichia coli as a fusion protein with glutathione S-transferase, and the recombinant OsDTC2 was indicated to function as stemar-13-ene synthase that converted syn-copalyl diphosphate to stemar-13-ene, a putative diterpene hydrocarbon precursor of the phytoalexin oryzalexin S. The level of OsDTC2 mRNA in suspension-cultured rice cells began to increase 3 h after addition of the elicitor and reached the maximum after 8 h. The expression of OsDTC2 was also induced in UV-irradiated rice leaves. In addition, we indicated that stemar-13-ene accumulated in the chitin-elicited suspension-cultured rice cells and the UVirradiated rice leaves.

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“…Plants possess a wide range of defense mechanisms to combat pathogens including the accumulation of phytoanticipins, phytochemicals synthesized constitutively as a pre-existing defense barrier, and by the inducible accumulation of phytoalexins, natural products possessing anti-microbial activities (1). Interestingly, these chemical defenses often encompass specific chemical classes for specific plant families.…”

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confidence: 99%

Functional Characterization of Premnaspirodiene Oxygenase, a Cytochrome P450 Catalyzing Regio- and Stereo-specific Hydroxylations of Diverse Sesquiterpene Substrates

Takahashi

Yeo

Zhao

et al. 2007

Journal of Biological Chemistry

106

105

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Solavetivone, a potent antifungal phytoalexin, is derived from a vetispirane-type sesquiterpene, premnaspirodiene, by a putative regio-and stereo-specific hydroxylation, followed by a second oxidation to yield the ␣,␤-unsaturated ketone. Mechanistically, these reactions could occur via a single, multifunctional cytochrome P450 or some combination of cytochrome P450s and a dehydrogenase. We report here the characterization of a single cytochrome P450 enzyme, Hyoscyamus muticus premnaspirodiene oxygenase (HPO), that catalyzes these successive reactions at carbon 2 (C-2) of the spirane substrate. HPO also catalyzes the equivalent regio-specific (C-2) hydroxylation of several eremophilane-type (decalin ring system) sesquiterpenes, such as with 5-epi-aristolochene. Moreover, HPO displays interesting comparisons to other sesquiterpene hydroxylases. 5-Epi-aristolochene di-hydroxylase (EAH) differs catalytically from HPO by introducing hydroxyl groups first at C-1, then C-3 of 5-epi-aristolochene. HPO and EAH also differ from one another by 91-amino acid differences, with four of these differences mapping to putative substrate recognition regions 5 and 6. These four positions were mutagenized alone and in various combinations in both HPO and EAH and the mutant enzymes were characterized for changes in substrate selectivity, reaction product specificity, and kinetic properties. These mutations did not alter the regio-or stereo-specificity of either HPO or EAH, but specific combinations of the mutations did improve the catalytic efficiencies 10 -15-fold. Molecular models and comparisons between HPO and EAH provide insights into the catalytic properties of these enzymes of specialized metabolism in plants.

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Two Classes of Plant Antibiotics: Phytoalexins versus "Phytoanticipins"

Cited by 328 publications

References 0 publications

Accumulation of soluble and wall-bound indolic metabolites in Arabidopsis thaliana leaves infected with virulent or avirulent Pseudomonas syringae pathovar tomato strains

Accumulation of soluble and wall-bound indolic metabolites in Arabidopsis thaliana leaves infected with virulent or avirulent Pseudomonas syringae pathovar tomato strains

Stemar‐13‐ene synthase, a diterpene cyclase involved in the biosynthesis of the phytoalexin oryzalexin S in rice

Functional Characterization of Premnaspirodiene Oxygenase, a Cytochrome P450 Catalyzing Regio- and Stereo-specific Hydroxylations of Diverse Sesquiterpene Substrates

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