Why Do Plants Have Cytochrome P‐450? Detoxification Versus Defence

Hendry, G. A. F.

doi:10.1111/j.1469-8137.1986.tb00578.x

Cited by 42 publications

(18 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This lack of accumulation was attributed to the high rate of camphor catabolic activity of suspension cultures (Falk et al, 1990), a process that may mimic the metabolic turnover of camphor produced in the oil glands of the intact plant (Croteau et al, 1984. Altematively, many monoterpenes are toxic to plant suspension cultures (Brown et al, 1987) and the metabolism of camphor by sage cells might thus represent such a detoxification system (Benveniste et al, 1982;Hendry, 1986). Similar detoxification systems are known in animal tissues in which inducible, microsomal Cyt P-450-dependent monooxygenases of broad specificity are involved in xenobiotic metabolism (Walker-Griffin et al, 1979), including the metabolism of dietary monoterpenes (Waller, 1969;Karp and Croteau, 1988).…”

mentioning

confidence: 99%

Induction and Characterization of a Cytochrome P-450-Dependent Camphor Hydroxylase in Tissue Cultures of Common Sage (Salvia officinalis)

Funk

Croteau

1993

Plant Physiol.

View full text Add to dashboard Cite

(+)-Camphor, a major monoterpene of the essential oil of common sage (Salvia officinalis), is catabolized in senescent tissue, and the pathway for the breakdown of this bicyclic ketone has been previously elucidated in sage cell-suspension cultures. In the initial step of catabolism, camphor is oxidized to 6-exo-hydroxycamphor, and the corresponding NADPH-and O,-dependent hydroxylase activity was demonstrated in microsomal preparations of sage cells.Severa1 well-established inhibitors of cytochrome P-450-dependent reactions, including cytochrome c, clotrimazole, and C O , inhibited the hydroxylation of camphor, and CO-dependent inhibition was partially reversed by blue light. Upon treatment of sage suspension cultures with 30 mM MnCI2, camphor-6-hydroxylase activity was induced up to 7-fold. A polypeptide with estimated molecular mass of 58 kD from sage microsomal membranes exhibited antigenic cross-reactivity in western blot experiments with two heterologous polyclonal antibodies raised against cytochrome P-450 camphor-5-exo-hydroxylase from Pseudomonas putida and cytochrome P-450 limonene-6s-hydroxylase from spearmint (Mentha spicata). Dot blotting indicated that the concentration of this polypeptide increased with camphor hydroxylase activity in microsomes of Mn'+-induced sage cells. These results suggest that camphor-6-exo-hydroxylase from sage is a microsomal cytochrome P-450 monooxygenase that may share common properties and epitopes with bacterial and other plant monoterpene hydroxylases.The biosynthetic capacity of plant cell cultures to produce various monoterpenoid, sesquiterpenoid, and diterpenoid substances has been demonstrated; however, the accumulation of monoterpenes in cultured cell systems is only rarely observed (Banthorpe et al., 1986; Charlwood et al., 1989). Studies with undifferentiated suspension cultures of common sage (Salvia officinalis) showed that the enzymes directly responsible for the conversion of the ubiquitous isoprenoid precursor, geranyl pyrophosphate (Fig. 1, structure l)', to (+)-camphor (Z), a major monoterpene of the intact plant, were readily detected during the late logarithmic phase of growth. Yet, no significant accumulation of camphor (C0.3 ng/g fresh

show abstract

mentioning

confidence: 99%

Induction and Characterization of a Cytochrome P-450-Dependent Camphor Hydroxylase in Tissue Cultures of Common Sage (Salvia officinalis)

Funk

Croteau

1993

Plant Physiol.

View full text Add to dashboard Cite

show abstract

“…Cyt P-450-linked enzymes have been implicated in biosynthetic pathways leading to the synthesis of lignin phenolics, membrane sterols, phytoalexins, and terpenoids (33). It has been postulated that plants have evolved highly specific Cyt P-450-linked secondary pathways to produce defense-related phytoalexins, while animals have evolved parallel less specific, Cyt P-450-linked systems to detoxify ingested phytoalexins and other xenobiotics (11,22 at the expense of the 450 nm peak (25). For this reason the CO-hemoprotein adduct with the 420 nm peak, termed P-420, is often considered to be a degradation product of Cyt P-450.…”

Section: Introductionmentioning

confidence: 99%

Multiple Forms of Plant Cytochromes P-450

Donaldson¹,

Luster²

1991

Plant Physiol.

159

View full text Add to dashboard Cite

Accumulating evidence indicates that there is a multiplicity of cytochrome P-450 enzymes in plants. These monooxygenases are implicated in the metabolism of sterols, terpenes, gibberellins, isoflavonoids, and xenobiotics. Evidence that cytochromes P-450 are involved in the detoxification of herbicides (chlorotoluron, primsulfuron, and diclofop) includes photoreversible CO inhibition of the reactions, and a requirement for 02 and NADPH. Several cytochromes P-450, Mr 45,000 to 65,000, have been isolated, including hydroxylases of cinnamic acid, 3,9-dihydroxypterocarpan, and digitoxin. In some cases the purified cytochrome P-450 has been successfully reconstituted with NADPH:cytochrome P-450 reductase (Mr 72,000-84,000 protein). This reductase appears to be a nonspecific electron donor to different forms of cytochrome P-450. Immunological techniques and specific inhibitors (triazoles, imidazole derivatives) are being used to characterize plant cytochromes P-450 and the NADPH:cytochrome P-450 reductase. Specific cytochromes P-450 are induced by wounding or pathogens, others are expressed in specific cell types. Plant cytochromes P-450 are found in various subcellular locations, including endoplasmic reticulum, plasma membranes, glyoxysomes, and perhaps mitochondria. A cytochrome P-450 demethylase from avocado has recently been sequenced and found to have a hydrophobic N terminus similar to the membrane anchor of cytochromes P-450 from other organisms. The existence of cytochromes P-450 in different subcellular locations suggests that there are many genes for cytochromes P-450 in plants which have yet to be identified and classified.Cyt P-450 are membrane-bound heme-containing proteins which have been implicated in a variety of oxidative reactions in plant tissues. A wide range of reactions are mediated by specific forms of these proteins. Cyt P-450-linked enzymes have been implicated in biosynthetic pathways leading to the synthesis of lignin phenolics, membrane sterols, phytoalexins, and terpenoids (33). It has been postulated that plants have evolved highly specific Cyt P-450-linked secondary pathways to produce defense-related phytoalexins, while animals have evolved parallel less specific, Cyt P-450-linked systems to detoxify ingested phytoalexins and other xenobiotics (11,22 at the expense of the 450 nm peak (25). For this reason the CO-hemoprotein adduct with the 420 nm peak, termed P-420, is often considered to be a degradation product of Cyt P-450.In addition to the nonspecific inhibition by CO, certain Cyt P-450 activities are selectively inhibited by various imidazole, pyrimidine, and triazole derivatives. Inhibitor binding also can be determined spectrophotometrically by changes in difference spectra. A typical Cyt P-450 spectrum of any mem-669 www.plantphysiol.org on May 10, 2018 -Published by Downloaded from

show abstract

“…The existence of P450(s) in higher plants was first proven in the early 1970s [36]. Accumulating evidence indicates that there is a multiplicity of P450(s) in plants [19] and they are best known and most studied for their oxygenase activity [1,16,36]. P450(s) have the capacity to attack a vast range of structurally unrelated chemicals to transform them into more polar, soluble products, diminishing or suppressing their toxicity [10].…”

mentioning

confidence: 99%

Enhanced activity of several herbicide-degrading enzymes: a suggested mechanism responsible for multiple resistance in blackgrass (Alopecurus myosuroides Huds.)

Letouzé

Gasquez

2003

Agronomie

View full text Add to dashboard Cite

To cite this version:Anne Letouzé, Jacques Gasquez. Enhanced activity of several herbicide-degrading enzymes: a suggested mechanism responsible for multiple resistance in blackgrass (Alopecurus myosuroides Huds. Abstract -Experiments were carried out to analyse enhanced herbicide metabolism mediated by cytochrome P450 monooxygenases (P450(s)) or glutathione-S transferases (GST(s)) as a possible mechanism responsible for multiple resistance in three blackgrass populations. The RA population is resistant to aryloxyphenoxypropionates (fops) and flupyrsulfuron, the RB to fenoxaprop-P, flupyrsulfuron and ureas and the RC to fenoxaprop-P, haloxyfop and clodinafop. Based on the coleoptile length, growth responses of seedlings to the herbicide responsible for resistance and to combined treatments of the herbicide plus P450(s) or GST(s), inhibitors were compared. Growth of the RA seedlings was significantly reduced with flupyrsulfuron plus malathion, suggesting that P450(s) activity may be involved in the resistance. In contrast, none of the four inhitors tested had an effect on the fop resistance. Fenoxaprop-P plus tridiphane, flupyrsulfuron plus malathion and ureas plus PBO or ABT significantly reduced the RB coleoptiles' growth. Therefore, multiple resistance in this population may be due to an elevation of P450(s) and GST(s) activity. In the RC population, PBO, ABT and tridiphane synergised clodinafop, haloxyfop and fenoxaprop-P effects, suggesting that the two enzymatic systems may also be involved in the RC resistances. multiple herbicide resistance / enhanced herbicide detoxification / P450(s)/GST(s) / Alopecurus myosuroides Huds.Résumé -L'amplification d'enzymes de détoxication des herbicides : un mécanisme possible responsable des résistances multiples chez le vulpin (Alopecurus myosuroides Huds.). Cette expérimentation a pour but d'analyser l'éventuelle implication de monooxygénases à cytochrome P450 (P450(s)) et de glutathione S-transférases (GST(s)) dans les résistances multiples observées chez trois populations de vulpin. La population RA résiste aux aryloxyphenoxypropionates (fops) et au flupyrsulfuron, la RB au fénoxaprop-P, au flupyrsulfuron et aux urées et la RC au fénoxaprop-P, à l'haloxyfop et au clodinafop. Les croissances de la première feuille des plantules exposées à l'herbicide seul et à un mélange "herbicide + inhibiteur" ont été analysées. La croissance des plantules RA est fortement réduite en présence de flupyrsulfuron associé au malathion. Ainsi, des P450(s) pourraient être impliquées dans la résistance de cette population. En revanche, les quatre inhibiteurs sont sans effet sur la résistance aux fops. Comparées à l'effet des herbicides utilisés seuls, les combinaisons fénoxaprop-P plus tridiphane, flupyrsulfuron plus malathion et urées plus PBO ou ABT réduisent significativement la croissance des plantules RB. Ces résultats suggèrent donc que des P450(s) et des GST(s) pourraient être responsables des résistances multiples de cette population. Pour finir, les résistances de la population RC p...

show abstract

Why Do Plants Have Cytochrome P‐450? Detoxification Versus Defence

Cited by 42 publications

References 37 publications

Induction and Characterization of a Cytochrome P-450-Dependent Camphor Hydroxylase in Tissue Cultures of Common Sage (Salvia officinalis)

Induction and Characterization of a Cytochrome P-450-Dependent Camphor Hydroxylase in Tissue Cultures of Common Sage (Salvia officinalis)

Multiple Forms of Plant Cytochromes P-450

Enhanced activity of several herbicide-degrading enzymes: a suggested mechanism responsible for multiple resistance in blackgrass (Alopecurus myosuroides Huds.)

Contact Info

Product

Resources

About