Increased disease susceptibility of transgenic tobacco plants with suppressed levels of preformed phenylpropanoid products.

Maher, Eileen A.; Bate, Nicholas J.; Ni, Weiting; Elkind, Yonatan; Dixon, Richard A.; Lamb, Christopher J.

doi:10.1073/pnas.91.16.7802

Cited by 245 publications

(157 citation statements)

References 26 publications

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“…The first is the respective roles of shikimate and quinate esters. If shikimate esters are described as transient intermediates, quinate derivatives such as chlorogenic acid commonly accumulate in some plant species and are alternatively described as growth regulators, disease resistance factors, antioxidants, and compounds affecting organoleptic quality of fruits (36,38,54,55 This leads to another interesting question concerning the branching of the pathway downstream of C3ЈH. Our data and previous reports (17,51) seem to indicate that the shikimate and quinate esters are not substrates of CCoAOMTs.…”

Section: Cyp98a3 a 3ј-hydroxylase Of P-coumaroyl Esters In Arabidopsismentioning

confidence: 48%

CYP98A3 from Arabidopsis thaliana Is a 3′-Hydroxylase of Phenolic Esters, a Missing Link in the Phenylpropanoid Pathway

Schoch

Goepfert

Morant

et al. 2001

Journal of Biological Chemistry

396

370

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The 4-and 5-hydroxylations of phenolic compounds in plants are catalyzed by cytochrome P450 enzymes. The 3-hydroxylation step leading to the formation of caffeic acid from p-coumaric acid remained elusive, however, alternatively described as a phenol oxidase, a dioxygenase, or a P450 enzyme, with no decisive evidence for the involvement of any in the reaction in planta. In this study, we show that the gene encoding CYP98A3, which was the best possible P450 candidate for a 3-hydroxylase in the Arabidopsis genome, is highly expressed in inflorescence stems and wounded tissues. Recombinant CYP98A3 expressed in yeast did not metabolize free pcoumaric acid or its glucose or CoA esters, p-coumaraldehyde, or p-coumaryl alcohol, but very actively converted the 5-O-shikimate and 5-O-D-quinate esters of trans-p-coumaric acid into the corresponding caffeic acid conjugates. The shikimate ester was converted four times faster than the quinate derivative. Antibodies directed against recombinant CYP98A3 specifically revealed differentiating vascular tissues in stem and root. Taken together, these data show that CYP98A3 catalyzes the synthesis of chlorogenic acid and very likely also the 3-hydroxylation of lignin monomers. This hydroxylation occurs on depsides, the function of which was so far not understood, revealing an additional and unexpected level of networking in lignin biosynthesis.Systematic genome sequencing is revealing a large number of orphan genes and their phylogenetic relatedness to genes with characterized function. EST 1 sequences, on the other hand, are providing preliminary information on levels, patterns of expression, and conservation of genes among species. Taken together, such information can be exploited as a clue to gene function and to track down missing steps in important pathways.The sequencing of the whole genome of Arabidopsis thaliana has revealed 273 cytochrome P450 genes distributed into 45 families and subfamilies (drnelson.utmem.edu/CytochromeP450. html, www.biobase.dk/P450/). P450 proteins thus form the largest superfamily of enzymes involved in plant metabolism, but the function of 80% of these enzymes is still unknown. Our attention was first drawn to the CYP98 family by its phylogeny and structure. An analysis of P450 phylogeny in A. thaliana (Fig. 1) shows that the CYP98 family is most closely related to CYP73A5, coding for the cinnamic-acid 4-hydroxylase, the second enzyme and first P450 in the phenylpropanoid pathway (1). CYP73A5 and the CYP98 family seem to have evolved from the same ancestor as CYP79 enzymes, some of which also, in common with CYP73A5, use aromatic substrates derived from the shikimate pathway (2, 3). It was thus tempting to speculate that the substrate of CYP98 enzymes was derived from aromatic amino acids as well. The Arabidopsis CYP98 family is formed by only three genes. CYP98A3 is present in single copy; CYP98A8 and CYP98A9 are 69% identical to one another and only 52% identical to CYP98A3. All P450 genes in the phenylpropanoid pathway (CYP73A5, CYP84A1, and CYP...

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Section: Cyp98a3 a 3ј-hydroxylase Of P-coumaroyl Esters In Arabidopsismentioning

confidence: 48%

CYP98A3 from Arabidopsis thaliana Is a 3′-Hydroxylase of Phenolic Esters, a Missing Link in the Phenylpropanoid Pathway

Schoch

Goepfert

Morant

et al. 2001

Journal of Biological Chemistry

396

370

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“…tomato [Solanum lycopersicum], tobacco [Nicotiana tabacum], and eggplant [Solanum melongena]), apple (Malus domestica), pear (Pyrus communis), plum (Prunus domestica), coffee (Coffea arabica), and artichoke (Tamagnone et al, 1998a;Clifford, 1999;Wang et al, 2003;Schü tz et al, 2004) and is believed to play important roles in free radical scavenging (Chen and Ho, 1997;Tamagnone et al, 1998b), enzymatic browning of fruits and vegetables (Walker, 1995), defense against fungal pathogens (Maher et al, 1994), and resistance to pathogenic insects (Dowd and Vega, 1996;Bushman et al, 2002). The biosynthetic routes leading to CGA in plants are not completely defined yet, and three possible paths have been proposed.…”

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confidence: 99%

Novel Hydroxycinnamoyl-Coenzyme A Quinate Transferase Genes from Artichoke Are Involved in the Synthesis of Chlorogenic Acid

Sonnante

D'Amore²,

Blanco³

et al. 2010

Plant Physiology

119

114

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Artichoke (Cynara cardunculus subsp. scolymus) extracts have high antioxidant capacity, due primarily to flavonoids and phenolic acids, particularly chlorogenic acid (5-caffeoylquinic acid [CGA]), dicaffeoylquinic acids, and caffeic acid, which are abundant in flower bracts and bioavailable to humans in the diet. The synthesis of CGA can occur following different routes in plant species, and hydroxycinnamoyl-coenzyme A transferases are important enzymes in these pathways. Here, we report on the isolation and characterization of two novel genes both encoding hydroxycinnamoyl-coenzyme A quinate transferases (HQT) from artichoke. The recombinant proteins (HQT1 and HQT2) were assayed after expression in Escherichia coli, and both showed higher affinity for quinate over shikimate. Their preferences for acyl donors, caffeoyl-coenzyme A or p-coumaroylcoenzyme A, were examined. Modeling and docking analyses were used to propose possible pockets and residues involved in determining substrate specificities in the HQT enzyme family. Quantitative real-time polymerase chain reaction analysis of gene expression indicated that HQT1 might be more directly associated with CGA content. Transient and stable expression of HQT1 in Nicotiana resulted in a higher production of CGA and cynarin (1,3-dicaffeoylquinic acid). These findings suggest that several isoforms of HQT contribute to the synthesis of CGA in artichoke according to physiological needs and possibly following various metabolic routes.

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“…PAL-modified and control transgenic plants were grown from seed and harvested after 5 weeks. C4H transgenic plants and corresponding controls were primary transformants cut back simultaneously and harvested after 4 weeks of regrowth.PAL lines evaluated were severely PAL sensesuppressed (160P3, second-generation progeny carrying a bean [Pkaseolus vulgaris] PAL transgene in the sense orientation), PAL-suppressed but recovering (274-T5 fifthgeneration selfed progeny), PAL-overexpressing (YEIO-6T1, first-generation selfed progeny), or operationally wild type (C17, first-generation progeny line that had lost the bean PAL transgene through segregation and therefore displayed a wild-type PAL phenotype), as described by Bate et al (1994) and Howles et al (1996). C4H lines were primary transformants carrying either an empty vector or an alfalfa (Medicago sativa) C4H transgene (Fahrendorf and Dixon, 1993) in the sense or antisense orientation, resulting in independent transformants with either normal, suppressed, or increased C4H activity.…”

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confidence: 99%

Reduced Lignin Content and Altered Lignin Composition in Transgenic Tobacco Down-Regulated in Expression of L-Phenylalanine Ammonia-Lyase or Cinnamate 4-Hydroxylase

et al. 1997

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We analyzed lignin content and composition in transgenic tobacco (Nicotiana tabacum) lines altered in the expression of the early phenylpropanoid biosynthetic enzymes L-phenylalanine ammonia-lyase and cinnamate 4-hydroxylase (C4H). The reduction of C4H activity by antisense expression or sense suppression resulted in reduced levels of Klason lignin, accompanied by a decreased syringyl/guaiacyl monomer ratio as determined by pyrolysis gas chromatography/mass spectrometry. Similar reduction of lignin levels by down-regulation of i-phenylalanine ammonia-lyase, the enzyme preceding C4H in the central phenylpropanoid pathway, did not result in a decreased syringyl/guaiacyl ratio. Rather, analysis of lignin methoxyl content and pyrolysis suggested an increased syringyl/guaiacyl ratio. One possible explanation of these results is that monolignol biosynthesis from L-phenylalanine might occur by more than one route, even at the early stages of the core phenylpropanoid pathway, prior to the formation of specific monolignol precursors.There is currently intense interest in modifying the content and / or composition of the cell wall structural polymer lignin as a means of improving the efficiency of the paper pulping process for forest trees or of increasing digestibility of forages for ruminant animals (Whetten and Sederoff, 1991; Boudet and Grima-Pettenati, 1996; Campbell and Sederoff, 1996).Recent studies have concentrated on attempts to downregulate the levels of enzymes involved in the reactions specific for lignin monomer synthesis by expression of homologous or heterologous antisense genes in transgenic plants (Dwivedi et al., 1994;Halpin et al., 1994;Ni et al., 1994; Atanassova et al., 1995;Van Doorsselaere et al., 1995;Sewalt et al., 1997). Although the biosynthetic pathway to lignin monomers is relatively well understood, involving consecutive hydroxylation and O-methylation reactions leading from p-coumaric acid via ferulic acid (the monomethoxylated precursor of the G residues of lignin) to sinapic acid (the dimethoxylated precursor of the S residues of lignin), it has recently been suggested that parallel pathways of monomer hydroxylation and methylation could occur at the level of the COA thioesters (Ye et al., 1994) or even at the level of the aldehydes formed after the first reduction of the COA thioesters (Matsui et al., 1994; Fig. 1).The existence of a metabolic grid for the O-methylation of monolignols would complicate the interpretation of experiments in which a single enzyme of the pathway was down-regulated. Indeed, severa1 reports of the effects of antisense inhibition of enzymes involved in the late reactions of monolignol biosynthesis have presented unpredicted and sometimes contradictory results. Ni et al. (1994) reported that modest down-regulation of COMT activity in transgenic tobacco (Nicofiana fabacum) leads to a small reduction in lignin content with no significant change in lignin composition. However, other groups have shown that strong down-regulation of COMT in tobacco or poplar (Populu...

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Increased disease susceptibility of transgenic tobacco plants with suppressed levels of preformed phenylpropanoid products.

Cited by 245 publications

References 26 publications

CYP98A3 from Arabidopsis thaliana Is a 3′-Hydroxylase of Phenolic Esters, a Missing Link in the Phenylpropanoid Pathway

CYP98A3 from Arabidopsis thaliana Is a 3′-Hydroxylase of Phenolic Esters, a Missing Link in the Phenylpropanoid Pathway

Novel Hydroxycinnamoyl-Coenzyme A Quinate Transferase Genes from Artichoke Are Involved in the Synthesis of Chlorogenic Acid

Reduced Lignin Content and Altered Lignin Composition in Transgenic Tobacco Down-Regulated in Expression of L-Phenylalanine Ammonia-Lyase or Cinnamate 4-Hydroxylase

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