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Introduction
Publications
Publications (103)
The enormous range of secondary metabolites produced within the plant kingdom includes many of scientific and commercial interest. There are frequently problems associated both with the study of secondary product biosynthesis in planta, and the reliability of agricultural systems for the production of commercially valuable products. In recent decad...
The enormous range of secondary metabolites produced within the plant kingdom includes many of scientific and commercial interest. There are frequently problems associated both with the study of secondary product biosynthesis in planta, and the reliability of agricultural systems for the production of commercially valuable products. In recent decad...
Chinese water chestnut ( Eleocharis dulcis (Burman f.) Trin ex Henschel) is a corm consumed globally in Oriental-style cuisine. The corm consists of three main tissues, the epidermis, subepidermis, and parenchyma; the cell walls of which were analyzed for sugar, phenolic, and lignin content. Sugar content, measured by gas chromatography, was higher...
The cDNAs from Hyoscyamus niger, encoding two enzymes of tropane-alkaloid biosynthesis, tropinone reductase I (TR-I) and hyoscyamine-6β-hydroxylase (H6H), have been simultaneously introduced into Nicotiana tabacum using particle bombardment and expressed under the control of the CaMV 35S promoter. Southern and Northern analyses confirmed integratio...
Th e history of recording and monitoring of Odonata in Britain is briefl y described. Results are then pre-sented which suggest that the country's Odonata fauna is currently in a period of fl ux, in a manner consist-ent with the actions of a high-level regulatory factor such as climate change. Th e ranges of many resident species are shifting. Leuc...
Summary Although three species of dragonfly became extinct in Britain and Ireland in the 1950s, the outlook for most of the present resident species is favourable, providing that appropriate freshwater habitat is increased and pollution reduced. A number of species are extending their range northwards, mostly as a result of overall temperature incr...
Sand Martins were trapped at an Oxfordshire colony during 1979–83. The return rate of adult males in following years was higher than for adult females, and adult females dispersed more than adult males in subsequent breeding seasons. The return rate of adults in the first year after capture appeared lower than in subsequent years but this was an ar...
As part of a study to explore the potential for new or modified bio-product formation, Beta vulgaris (sugar beet) has been genetically modified to express in root-organ culture a bacterial gene of phenylpropanoid catabolism. The HCHL gene, encoding p-hydroxycinnamoyl-CoA hydratase/lyase, was introduced into B. vulgaris under the control of a CaMV 3...
Hydroxycinnamic acid amides are a class of secondary metabolites distributed widely in plants. We have identified two sinapoyl spermidine derivatives, N-((4'-O-glycosyl)-sinapoyl),N'-sinapoylspermidine and N,N'-disinapoylspermidine, which comprise the two major polyamine conjugates that accumulate in Arabidopsis thaliana seed. Using metabolic profi...
Plant polyphenolics exhibit a broad spectrum of health-promoting effects when consumed as part of the diet, and there is considerable interest in enhancing the levels of these bioactive molecules in plants used as foods. AtMYB12 was originally identified as a flavonol-specific transcriptional activator in Arabidopsis thaliana, and this has been con...
Members of the BAHD family of plant acyl transferases are very versatile catalytically, and are thought to be able to evolve new substrate specificities rapidly. Acylation of anthocyanins occurs in many plant species and affects anthocyanin stability and light absorption in solution. The versatility of BAHD acyl transferases makes it difficult to i...
Four related phenolic amides previously undescribed from the species were revealed during metabolic profiling of potato (Solanum tuberosum) tubers. N(1),N(12)-Bis(dihydrocaffeoyl)spermine (kukoamine A) and N(1),N(8)-bis(dihydrocaffeoyl)spermidine were positively identified by comparison with authentic standards, while the structures N(1),N(4),N(12)...
Metabolite profiling has been carried out to assess the compositional changes occurring in potato tubers after genetic modifications have been made to different metabolic pathways. Most major features in the (1)H NMR and HPLC-UV profiles of tuber extracts have been assigned. About 40 GM lines and controls belonging to 4 groups of samples (derived f...
4-Hydroxycinnamoyl-CoA hydratase/lyase (HCHL), a crotonase homologue of phenylpropanoid catabolism from Pseudomonas fluorescens strain AN103, led to the formation of 4-hydroxybenzaldehyde metabolites when expressed in hairy root cultures of Datura stramonium L. established by transformation with Agrobacterium rhizogenes. The principal new compounds...
Lipopolysaccharide (LPS) is a ubiquitous component of Gram-negative bacteria which has a number of diverse biological effects on eukaryotic cells. In contrast to the large body of work in mammalian and insect cells, the effects of LPS on plant cells have received little attention. LPS can induce defense-related responses in plants, but in many case...
The lantibiotic nisin is an antimicrobial peptide produced by Lactococcus lactis. As with all lantibiotics, nisin contains a number of dehydro-residues and thioether amino acids that introduce five lanthionine rings into the target peptide. These atypical amino acids are introduced by post-translational modification of a ribosomally synthesized pre...
The gene for a bacterial enoyl-CoA hydratase (crotonase) homolog (HCHL) previously shown to convert 4-coumaroyl-CoA, caffeoyl-CoA, and feruloyl-CoA to the corresponding hydroxybenzaldehydes in vitro provided an opportunity to subvert the plant phenylpropanoid pathway and channel carbon flux through 4-hydroxybenzaldehyde and the important flavor com...
Inoculation of pepper leaves, Capsicum annuum cv. Early Calwonder ECW 10R, with strains of Xanthomonas campestris led to an accumulation of the phenolic conjugates feruloyltyramine (FT) and p-coumaroyltyramine (CT) 24 h postinoculation in nonhost- and gene-for-gene-determined incompatible interactions with X. campestris pv. campestris and X. campes...
Sinapic acid is a major phenylpropanoid in Brassicaceae providing intermediates in two distinct metabolic pathways leading
to sinapoyl esters and lignin synthesis. Glucosyltransferases play key roles in the formation of these intermediates, either
through the production of the high energy compound 1-O-sinapoylglucose leading to sinapoylmalate and s...
An Arabidopsis thaliana line that is mutant for the R2R3 MYB gene, AtMYB4, shows enhanced levels of sinapate esters in its leaves. The mutant line is more tolerant of UV-B irradiation than wild type. The increase in sinapate ester accumulation in the mutant is associated with an enhanced expression of the gene encoding cinnamate 4-hydroxylase, whic...
The structure and mechanical properties of onions are important factors affecting their textural quality. The onion bulb consists of several layers of pigmented, papery scales surrounding fleshy storage scales that comprise an upper epidermis, an intermediate parenchyma tissue, and a lower epidermis. The purpose of this study was to examine the che...
Tomato leaves or cotyledons expressing the Cf-2 or Cf-9 Cladosporium fulvum resistance genes induce salicylic acid (SA) synthesis following infiltration with intercellular washing fluid (IF) containing the fungal peptide elicitors Avr2 and Avr9. We investigated whether SA was required for Cf gene-dependent resistance. Tomato plants expressing the b...
There is growing recognition that many phenolic secondary metabolites present in foodstuffs may possibly exert beneficial effects on human health. This may to some degree be mediated via antioxidant actions, but a range of more specific pharmacological effects have also been proposed. Given this background, there may be favourable consequences for...
There is growing recognition that many phenolic secondary metabolites present in foodstuffs may possibly exert beneficial effects on human health. This may to some degree be mediated via antioxidant actions, but a range of more specific pharmacological effects have also been proposed. Given this background, there may be favourable consequences for...
A range of analogues of N-methylputrescine and tropinone were fed to transformed root cultures of Nicotiana rustica and/or a Brugmansia candida×aurea hybrid. These cultures were made by the transformation of the relevant plant species with Agrobacterium rhizogenes. A number of the metabolites, notably those showing a relatively modest alteration in...
The enzyme 4-hydroxycinnamoyl-CoA hydratase/lyase (HCHL), which catalyzes a hydration and two-carbon cleavage step in the degradation of 4-hydroxycinnamic acids, has been purified and characterized from Pseudomonas fluorescens strain AN103. The enzyme is a homodimer and is active with three closely related substrates, 4-coumaroyl-CoA, caffeoyl-CoA,...
The lantibiotic nisin is an antimicrobial peptide produced by Lactococcus lactis. As with all lantibiotics, nisin contains a number of dehydro-residues and thioether amino acids that introduce five lanthionine rings into the target peptide. These atypical amino acids are introduced by post-translational modification of a ribosomally synthesized pre...
The PRS gene family in Saccharomyces cerevisiae consists of five genes each capable of encoding a 5-phosphoribosyl-1(alpha)-pyrophosphate synthetase polypeptide. To gain insight into the functional organization of this gene family we have constructed a collection of strains containing all possible combinations of disruptions in the five PRS genes....
The putative gene encoding acetyl-CoA carboxylase, accA, has been isolated from Aspergillus nidulans. This single-copy gene has an open reading frame (ORF) of 6864 bp and contains two small introns near the 5'-end. A short ORF upstream of the ATG start codon has been identified in this gene by RT-PCR. Based on sequence homology to acetyl-CoA carbox...
In Saccharomyces cerevisiae, an open reading frame, YOL061w, encodes a polypeptide with sequence similarity to the four known 5-phosphoribosyl-1(alpha)-pyrophosphate synthetase (PRS) genes since it contains a divalent cation binding site and a phosphoribosyl pyrophosphate binding site. We regard YOL061w as the fifth member of the PRS gene family, P...
Several complex phenotypic changes are induced when the transcription factor AmMYB308 is overexpressed in transgenic tobacco plants. We have previously shown that the primary effect of this transcription factor is to inhibit phenolic acid metabolism. In the plants that we produced, two morphological features were prominent: abnormal leaf palisade d...
In Saccharomyces cerevisiae , an open reading frame, YOL061w, encodes a polypeptide with sequence similarity to the four known 5-phosphoribosyl-1(α)-pyrophosphate synthetase (PRS) genes since it contains a divalent cation binding site and a phosphoribosyl pyrophosphate binding site. We regard YOL061w as the fifth member of the PRS gene family, PRS5...
The aim of this study was to examine the changes of cell wall chemistry of carrots (Daucus carota cv. Amstrong) during maturation and storage in relation to textural properties. Alcohol-insoluble residues were prepared and extracted sequentially with water and cyclohexane-trans-1,2-diaminetetraacetic acid (CDTA) to leave residues. The extracts and...
High pressure liquid chromatography profiles of barley leaf epidermal soluble and cell wall-bound phenolics were analyzed in response to challenge with the fungal pathogen Erysiphe graminis f. sp. hordei. Only one soluble phenolic was found to accumulate differentially in a broad spectrum resistance reaction controlled by mlo resistance alleles in...
MYB-related transcription factors are known to regulate different branches of flavonoid metabolism in plants and are believed to play wider roles in the regulation of phenylpropanoid metabolism in general. Here, we demonstrate that overexpression of two MYB genes from Antirrhinum represses phenolic acid metabolism and lignin biosynthesis in transge...
A gene encoding a novel enoyl-SCoA hydratase/lyase enzyme for the hydration and nonoxidative cleavage of feruloyl-SCoA to
vanillin and acetyl-SCoA was isolated and characterized from a strain of Pseudomonas fluorescens. Feruloyl-SCoA is the CoASH thioester of ferulic acid (4-hydroxy-3-methoxy-trans-cinnamic acid), an abundant constituent of plant c...
Modified nisin molecules, synthesised by strains of Lactococcus lactis with deliberately mutated nisA genes, have been characterised using Fourier transform ion cyclotron resonance mass spectrometry and electrospray ionisation. The predicted substitutions in the three nisin variants synthesised were first confirmed by precise measurement of the mol...
The biosynthesis of the tropane alkaloids in transformed root cultures of Datura stramonium has been studied using sodium [1,2-13C2]acetate, (R,S)-[2,3-13C2]-1-(1-methyl-2-pyrrolidinyl)propan-2-one {(R,S)-[2‘,3‘-13C2]hygrine}, ethyl (R,S)-[1,2-13C2,2-14C]-2-(1-methyl-2-pyrrolidinyl)acetate, and ethyl (R,S)-[2,3-13C2,3-14C]-4-(1-methyl-2-pyrrolidiny...
The cold alkali-labile cell wall phenolics of carrot storage roots have been examined by diode-array HPLC following sequential treatment of purified wall material with aqueous sodium hydroxide of increasing strength. In addition to 4-hydroxybenzoic acid and ferulic acid, which have previously been reported from this source, a range of other typical...
Texture is a major quality attribute of plant-based foods. The plant cell wall is a key determinant of texture in fruit and vegetables; its properties influence the way in which plant tissues undergo mechanical deformation and failure during mastication. Processes such as cooking, and physiological events such as ripening can reduce the strength of...
Sugarbeet, a form of Beta vulgaris var vulgaris, fails to soften completely after heating at 100°C for several hours. This is due to thermal stability of the cell–wall polymers involved in cell–cell adhesion. In contrast, beetroot softens within 25–30 min due to a relatively rapid increase in the ability of the cells to separate. Information concer...
Nisin, a 34 residue lantibiotic produced by strains of Lactococcus lactis subsp. lactis, exerts antimicrobial activity against Gram-positive bacteria at the cytoplasmic membrane. The structural aspects of nisin which facilitate membrane interaction and permeabilization have been investigated in planar lipid bilayers and liposomes with proteolytic f...
An optimized high performance liquid chromatography (HPLC) procedure has been developed for the analysis and quantification of all of the known ferulic acid dehydrodimers, and the principle phenolic aldehydes and acids, found in the cell walls of higher plants. The HPLC system uses an ODS2 reverse phase column (5 μm particle size) eluted with a met...
Chinese water chestnut (CWC) is a vegetable in which the edible storage parenchyma exhibits thermal stability to texture. This property has been attributed to the presence of large quantities of simple phenolics which exhibit pH-dependent autofluorescence. The identities of the major phenolic components were assessed by reverse-phase HPLC after seq...
The incorporation of isotope from specifically-labelled 3-phenyllactic acid 4 or littorine 7 into 3α-phenylacetoxytropane 10, 3α-phenylacetoxy-6β,7β-epoxytropane and 3α-(2′-hydroxyacetoxy)-tropane 9 has been demonstrated. Transformed root cultures of Datura stramonium or Brugmansia (Datura) Candida x B. aurea incorporated fed (RS)-3-phenyl[1,3-13C2...
Transformed organ cultures formed following transformation of plant tissues with Agrobacterium species owe their phenotypes to alterations in hormone metabolism. Exogenously supplied hormones have been used to probe the relationship between the growth and morphology of transformed root cultures of a number of species and their ability to accumulate...
Plant cell and tissue culture has been used for many years to study and influence alkaloid biosynthesis from a wide range of plant species grown in culture. Nondifferentiated cultures have often been used, with variable degrees of success regarding the establishment and maintenance of productive cultures (Fujita 1990; Wilson 1990). In many cases co...
It has long been an objective to increase or decrease the yield of plant-derived secondary products. Over the last few hundred years this has been achieved in a few examples by selective breeding within the natural germplasm pool. In the 1960s, however, the potential of using plant cell in vitro cultures to enhance variation was developed, and sinc...
Transformed root cultures of BRUGMANSIA CANDIDA were established by infection with AGROBACTERIUM RHIZOGENES LBA 9402. Several clones with different growth index and tropane alkaloid pattern and content were obtained and two were examined in depth. The alkaloid content and pattern changed during the time course. At 21 days of culture clone 1 reveale...
Alkaloid production by several Agrobacterium rhizogenes-transformed root lines of Nicandra physaloides was studied. Early in the culture cycle all lines contained predominantly hygrine, which has previously been reported to be the major alkaloid in roots of this plant. A number of other hygrine-derived alkaloids were identified, and these generally...
8-Thiabicyclo[3.2.l]octan-3-one, the sulphur analogue (replacing the methylaza bridge) of tropinone, was fed to Datura stramonium transformed root cultures. The compound was metabolized to a large degree. Notable products included the reduction product, 8-thiabicyclo[3.2.1]octan-3-ol, analogous to tropine, and also the derived 3-O-acetyl ester. In...
Increasingly, as a result of recent biochemical work, there exists a realistic possibility of taking a molecular genetic approach to the manipulation of alkaloid-producing pathways in plant tissue cultures. In the pathways forming indole alkaloids in CATHARANTHUS ROSEUS, tropane alkaloids in DATURA and HYOSCYAMUS species, and nicotine in NICOTIANA...
The factors by which the endogenous regulation of tropane-alkaloid biosynthesis may be effected have been examined in a transformed root culture of Datura stramonium. Pools of intermediates showed a subculture-related maximal accumulation, as did the enzyme activities by which they are synthesised and/or metabolised. The end-products, principally h...
The relative contributions made by the L-arginine/agmatine/N-carbamoylputrescine/putrescine and the L-ornithine/putrescine pathways to hyoscyamine formation have been investigated in a transformed root culture of Datura stramonium. The activity of either arginine decarboxylase (EC 4.1.1.19) or ornithine decarboxylase (EC 4.1.1.17) was suppressed in...
The treatment of root cultures of Datura stramonium with copper and cadmium salts at external concentrations of approximately 1mM has been found to induce the rapid accumulation of high levels of sesquiterpenoid defensive compounds, notably lubimin and 3-hydroxylubimin. These compounds were undetectable in unelicited cultures. No net change was see...
Petioles from over 1000 individual plants of the genera Datura, Scopolia and Hyoscyamus were analysed to establish the variation in the levels and patterns of tropane alkaloids which occur between plants. Transformed root cultures were initiated from plants of which analyses suggested extremely high or low alkaloid biosynthetic capacities, or favou...
Transformed root cultures of Nicotiana rustica have been generated in which the gene from the yeast Saccharomyces cerevisiae coding for ornithine decarboxylase has been integrated. The gene, driven by the powerful CaMV35S promoter with an upstream duplicated enhancer sequence, shows constitutive expression throughout the growth cycle of some lines,...
Using in combination an analysis of (i) the levels of enzyme activities present, (ii) the pool sizes of metabolic intermediates and end products and (iii) the effects of feeding metabolic intermediates, the limitations ℴ flux into tropane alkaloids in a Datura root culture have been examined. This culture, produced by transforming a Datura candida...
Countries of origin of foreign-ringed Black-headed Gulls (Larus ridibundus) sighted in Central London were compared with recovery localities of non-breeding birds ringed in Central London and reported abroad. The proportion of the total numbers of birds ringed between 1983 and 1987 in countries bordering the North Sea or the Baltic and subsequently...
Putrescine is an important precursor of alkaloids such as nicotine in Nicotiana and scopolamine and hyoscyamine in Datura. It acts at the interface between primary and secondary metabolism and its primary role is as an intermediate in the formation of polyamines which have important roles in the growth of animal and microbial as well as plant cells...
The state of greater covert moult in 145 first winter Coal Tits Parus ater from 5 suburban English sites was examined. There was a statistically significant difference between sites in the number of greater coverts moulted, with a tendency for birds from more northerly and easterly sites to have more old, unmoulted greater coverts than birds from m...
Root cultures formed following transformation by A grobacterium rhizogenes offer a stable and reproducible system for the study of secondary metabolism (see review Hamill et al. 1987). The production of the tropane alkaloids, hyoscyamine (atropine) and hyoscine (scopolamine) have been studied by a number of different groups in a range of related so...
Transformed roots of Catharanthus roseus were obtained following infection of detached leaves with Agrobacterium rhizogenes. Roots would not grow in full strength Gamborg's B5 medium but would grow satisfactorily if the medium was diluted to one half strength. Little alkaloid appeared in the growth medium but root tissue contained a high level and...
The study of plant secondary metabolism, with the aim of bio-technological exploitation using tissues grown in vitro, has traditionally tended to use dispersed cell cultures or callus. The cultures usually have a strong tendency to be genetically and biochemically unstable and often synthesize very low levels of secondary products. Recently we have...
A suspension culture was produced by the phytohormone treatment of hairy roots resulting from infection of Nicotiana rustica with Agrobacterium rhizogenes. This was used as a source of protoplasts for the production of single-cell-derived clones. After conditions for protoplast release were optimised, it was possible to induce high rates of cell di...
For some years, there has been great interest in the exploitation of plant cell cultures to produce fine chemicals. With a few exceptions, progress in commercialization has been slow, largely due to the low and/or unstable productivity of many undifferentiated cultures. Recent developments leading to the production of rapidly growing, organized, 'h...
The toxicity of Cinchona alkaloids to cell cultures of C. ledgeriana has been studied in relation to alkaloid uptake and possibilities for selecting high-yielding cell lines. The most toxic, quinine, was completely toxic at 5.5 mM. Both quinine and quinidine were more toxic than their unmethoxylated precursors, cinchonidine and cinchonine. The perm...
The addition of exogenous nicotinic acid, nicotinamide or nicotine was studied with reference to their effects on growth and alkaloid production by hairy root cultures of Nicotiana rustica. Nicotinic acid and nicotinamide were toxic (50% phytostatic dose being 2.4 and 9 mM respectively) while nicotine was not toxic below 10 mM. Nicotinic acid (up t...
Hairy root cultures were obtained following infection of a range of Nicotiana species with Agrobacterium rhizogenes. Such cultures synthesized alkaloids in amounts which closely reflected, in both qualitative and quantitative terms, the biosynthetic capacity of roots from the uninfected parent species or variety. Cultures also released alkaloids fr...