R.K.S. Wood's research while affiliated with Imperial College London and other places

Publications (52)

Chapter
Although this Workshop is about the biology as well as the molecular biology of host/parasite relations I think that my comments would be spread too thinly were they on both. Therefore, and because of what I expect to be the preoccupation of the Workshop, I shall confine them very largely to interactions at cellular and sub-cellular levels. Even th...
Article
Pectic and hemicellulosic-rich fractions were isolated from cell walls of untreated susceptible cucumber plants and of plants in which resistance had been induced systemically by prior inoculation of lower leaves with Colletotrichum lagenarium, 9 days before extraction. Filtrates from cultures of C. lagenarium contained enzymes which degraded pecti...
Article
Isolates R1 and R2 of Puccinia recondita f. sp. tritici of low or high virulence on leaves of a series of cultivars of wheat behaved very similarly up to the formation of appressoria above stomata and sub‐stomatal vesicles. Differences in growth of hyphae and in responses of host cells became clearly apparent only 24 h after infection; they then in...
Article
Injection of cucumber cotyledons with polyacrylic acid (PA), acetylsalicylic acid (ASA) and salicylic acid (SA) induced resistance to inoculations with Colletrichum Iagenarium when inoculation followed injection by 96 h but not by 24 h. Size and number of lesions were greatly decreased. Resistance was greatest in injected cotyledons but was also pr...
Article
Of eight fungicides tested in vitro against a strain of Phytophthora palmivora pathogenic to cocoa, cuprous oxide, cycloheximide and mancozeb were highly toxic at low concentrations at most stages in the development of the fungus with ED50 < 100 p.p.m. for growth of mycelium, <200 p.p.m. for formation of sporangia, <500 p.p.m. for germination of sp...
Article
en Part of the acidic pectic polysaccharide fraction from leaves of Phaseolus vulgaris cv. Red Mexican agglutinated cells of several plant pathogenic and non pathogenic bacteria. Acidic pectic polysaccharides from leaves of various species and cultivars of higher plants agglutinated cells of Race 1 and 2 of Pseudomonas phaseolicola. Race 1 cells we...
Article
Pectic enzymes produced by Erwinia atroseptica in host tissue and in liquid culture were compared. Culture filtrates contained three polygalacturonate trans-eliminase isoenzymes with isoelectric points at pH 9·7, 10·2 and 10·35, with the same pH optimum but with slightly different modes of action in degrading pectic substances. One of the enzymes h...
Article
Chroma tograms of extracts from roots of eggplant, pepper and tomato plants inoculated with Verticillium dahliae contained many substances toxic to Cladosporium cucumerinum. Of these substances a few were also present in extracts from uninoculated plants, but most were present in extracts from uninoculated plants which had been treated with benomyl...
Book
A NATO Advanced Study Institute on "Active Defence Mechanisms in Plants" was held at Cape Sounion, Greece, 21 April - 3 May 1981. It succeeded a similar Institute held at Porte Conte, Sardinia in 1975 on "Specificity in Plant Diseases. " What are active defence mechanisms in the context of plant disease in which a plant, the host, may be damaged by...
Article
A fraction obtained from cotyledons of Phaseolus vulgaris cv. Red Mexican agglutinated cells of avirulent Race 1 isolates of Pseudomonas phaseolicola more actively than it agglutinated cells of virulent Race 2 isolates; it also agglutinated human erythrocytes. Carbohydrate in the fraction agglutinated the bacteria whereas haemagglutination was caus...
Article
Irradiation of etiolated bean hypocotyls with u.v. light for short periods immediately before inoculation greatly decreased resistance to races of Colletotrichum lindemuthianum otherwise avirulent, and to C. lagenarium and C. coffeanum. Resistance was induced when susceptible hypocotyls were irradiated with u.v. light and inoculated 24 or 48 h late...
Article
High endo-pectin lyase (endo-PL) activity occurred in vascular tissue of susceptible tomato cuttings (cv. Gem S.) 3 days after infection by Verticillium albo-atrum and before symptoms appeared. The enzyme also occurred in a near isogenic resistant cultivar (Gem R.) but at much lower levels. Endo-polygalacturonase (endo-PG) was also found but only a...
Article
Single polysaccharidases of Verticillium albo-atrum degraded cell walls from vascular and other tissues of tomato stems without previous or simultaneous action of other enzymes. Endoxylanase, exo-galactanase and exo-arabinase of the pathogen had pH optima c. 5, 3 and 5 respectively. Cellulase degraded soluble and insoluble cellulose at optimum pH c...
Article
Injection of Red Mexican bean leaves with Pseudomonas phascolicola Race 2 (compatible, 18 h before P. mors-prunorum or P. phaseolicola Race 1 (incompatible), or simultaneous inoculation with compatible and incompatible bacteria (3:1) greatly delayed the appearance of hypersensitive responses. When compatible bacteria were inoculated 12 h or less be...
Article
Disks from pea leaves were floated on solutions of various substances; pisatin levels in the solutions and in the disks were measured after incubation. Filtrates from cultures of Ascochyta pisi and Mycosphaerella pinodes which increased accumulation were no more effective than were uninoculated media; filtrates from cultures of Penicillium expansum...
Book
A NATO Advanced Study Institute on "Phytotoxins in Plant Diseases" was held in Pugnochiuso (Italy) in June 1970. It was concerned mainly with the chemistry and mode of action of substances toxic to higher plants which are produced by pathogenic bacteria and fungi. The role of such substances in specificity was consider­ ed but largely in relation t...
Article
Phaseollin accumulated in hypersenstive and susceptiblee responses of leaves of bean (Phaseolus vulgaris) inoculated with Pseudomonas mors-prunorum or P. phaseolicola Races 1,2. At 100 μg/ml it did not decrease growth of P. mors-prunorum or P. phaseolicola but did prevent growth of the saprophyte Brevibacterium linens for 3 days.The isoflavanoid co...
Article
Scanning and transmission electron microscopy and light microscopy were used to investigate the structure and morphology of uredospores of Uromyces appendiculatus. Results are discussed in terms of the relationship between form and function.
Article
Crude dialysed extracts from rots of cucumber fruit infected by Erwinia carotovora caused cell separation and death of protoplasts in normal unplasmolysed tissues of different plants. By ammonium sulphate precipitation, gel filtration and isoelectric focusing a pectate trans-eliminase (PTE) was isolated from rot extracts and purified. When used at...
Article
The fine structure of susceptible hypocotyls of Phaseolus vulgaris L. reacting to the anthracnose pathogen, Colletotrichum lindemuthianum (Sacc. and Magn.) Bri. and Cav. is described.Cytoplasm of ungerminated conidia is closely packed with ribosomes and contains inclusions of two types. Both may also be recognized in germ tubes but one appears alte...
Article
Induction and catabolite repression of synthesis of cell wall degrading enzymes by the vascular wilt fungi Verticillium albo-atrum and Fusarium oxysporum f. sp. lycopersici have been studied. In cultures containing inorganic salts and tomato stem cell walls each fungus produced a range of extracellular, polysaccharide degrading enzymes. In V. albo-...
Article
THE cell walls of higher plants were long regarded as essentially inert structures which functioned mainly as mechanical barriers to the expansion of protoplasts under turgor pressure and as skeletal supports in tissues. It is now known, however, that they contain a number of hydrolytic enzymes at least one of which is a hydroxyproline-rich protein...
Article
Resistance of Phaseolus vulgaris L. to Colletotrichum lindemuthianum Sacc. et Magn. Bri. et Cav., the cause of anthracnose, was studied physiologically and by light and electron microscopy of a number of combinations of host cultivar and pathogen race giving reactions ranging from highly susceptible to highly resistant.Hypersensitive death of cells...
Article
Full-text available
THE vascular wilt fungi Verticillium albo-atrum and Fusarium oxysporum f. sp. lycopersici, pathogenic to tomato plants, are characteristically confined to the vascular elements where they produce substances causing disease symptoms. The identity of these substances is still controversial. Both fungi, however, readily produce in vitro enzymes that d...
Article
Leaves of French bean (Phaseolus vulgaris) cv. Canadian Wonder and Red Mexican were infiltrated with suspensions of Pseudomonas phaseolicola (Races 1,2), P. mors-prunorum or P. fluorescens to give a hypersensitive (incompatible), susceptible (compatible) or no response. They were also infiltrated with solutions of ammonia. Measurement of ammonia in...
Article
The Mussell and Morré method for estimating the activity of chain-splitting pectic enzymes was tested with sections of parenchyma from cucumber fruit and potato tubers. It proved to be a very sensitive test for the pectate trans-eliminase of Erwinia atroseptica, between 10 and 100 times as sensitive as a viscometric method based on degradation of p...
Article
WHEN an avirulent fungus infects resistant plant tissue it often kills only a small number of cells and remains confined to the dead cells. This acute, very localized reaction is referred to as a hypersensitive response. When the pathogen is not an obligate biotroph, death of these cells need not explain why it does not continue to grow. In certain...
Article
The phytoalexin, pisatin, was detected in host tissues 24 h after inoculation of pea leaflets with spores of the leaf-spotting pathogens Ascochyta pisi and Mycosphaerella pinodes. Pisatin continued to accumulate in infected tissue as A. pisi lesions developed and was present in inhibitory concentrations in the brown tissue beyond the region coloniz...
Article
Extracts of limited and spreading lesions caused by Mycosphaerella pinodes on detached pea leaflets contained proteolytic, cellulolytic, and pectolytic enzymes although only in spreading lesions was there much degradation of cell walls. The brown tissue from limited M. pinodes lesions was resistant to maceration by enzymes from spreading lesions. L...
Article
Orange and carrot extract, pollen diffusate, peptone, and a mixture of glucose and casamino acids greatly stimulated germination of conidia of Colletotrichum lindemuthianum which was poor in water. Urea and glucose and casamino acids separately had little effect. Orange extract and the glucose/casamino acids mixture altered the ways in which the pa...
Article
The leaf-spot pathogens, Ascochyta pisi and Mycosphaerella pinodes, both cause limited, necrotic lesions in detached pea leaflets suspended above water. When leaflets were floated on water A. pisi lesions were still limited, but those caused by M. pinodes spread rapidly to occupy all the leaflet tissue. Increasing the numbers of spores in inocula d...
Article
Various substances alter the activity of quintozene, tecnazene and dichloran towards Botrytis cinerea. The toxicity of tecnazene and dichloran is increased in agar gels, and in 0·1 % solutions of agar, sodium carboxymethylcellulose, sodium polypectate and gelatine; there are no similar effects with quintozene. A glucose/casein hydrolysate solution...
Article
When tomato plants resistant toVerticillium albo-atrum become infected with this fungus the parasite grows very little in the stem. The stem, however, responds by producing many tyloses. In susceptible tomato plants in which the parasite is more abundant few tyloses occur, but after some weeks when the parasite begins to disappear from the lower pa...
Article
Calcium which activates enzymes that split chains of pectic substances also increases the activity of macerating enzymes produced in culture byErwinia aroideae. EDTA suppresses both types of activity. Separation on carboxymethylcellulose gave a number of fractions in each of which there was reasonably close correspondence between macerating, chain-...
Article
CULTURE fluids of the soft-rotting bacterium Erwinia aroideae contain polygalacturonase activity and cause maceration of parenchymatous tissue. Much indirect evidence has indicated that polygalacturonase causes maceration; for example, both activities respond in the same way to pH, precipitation by organic solvents, and dialysis1. It has been demon...
Article
The parasitism by two strains of Corticium solani (Prill. & Delacr.) Bourd. & Galz. and one of C. praticola Kotila has been investigated. A lettuce strain of C. solani parasitized lettuce but not cabbage: a cabbage strain parasitized cabbage but not lettuce. C. praticola parasitized both. Wheat was not parasitized by the strains of C. solani but wa...
Article
Comparative studies were made on the spread of the pathogen and development of disease symptoms in root-inoculated plants, resistant and susceptible to V. albo-atrum Reinke & Barth. Disease symptoms became obvious in the susceptible variety after 10 days and gradually increased, whereas only slight disease symptoms were found in the resistant varie...
Article
An isolate of Verticillium albo-atrum virulent on tomato produced polygalacturonase abundantly in suitable culture media. Secretion was greatly stimulated by pectic substances, and by organic, as compared with inorganic sources of nitrogen. Degradation of polypectate by culture filtrates decreased sharply when only about 25% of available glycosidic...
Article
CELERY seed often carries pycnidia of the fungi Septoria apii and Septoria apii-graveolentis. It is ocommonly assumed that spores from those pycnidia infect young seedlings, and that this is the most important way in which the diseases caused by these two fungi start each year. There are, however, the following reasons for doubting the validity of...
Article
The activities of pectic enzymes in extracts from sound apples and from apples rotted by different fungi are described. Sclerotinia fructigenaand Botrytis cinerea rots had little or no polygalacturonase or macerating enzyme activity, but Penicillium expansum rots were very active in these respects. Extracts from each of the rots had very high pecti...
Article
The rate at which the fungi grew through apples was determined in various ways and used to estimate their rate of linear advance. Five fungi were studied;they were Sclerotinia fructigena (firm-brown coloured rot, rapid growth through apples), Botrytis cinerea (soft, light-brown coloured rot, rapid growth through apples), Psyrenochaeta furfuracea (f...

Citations

... If the introduced strain is equipped with certain discriminating feature(s) over the indigenous microflora that confers it the capacity to compete for restricted space and nutrients, the strain succeeds in colonizing the rhizosphere. Characteristics that offer selective advantage to the introduced strain in the rhizosphere include the flagellar motility (de Weger et al. 1987), ability to utilize root exudates and adherence to root surfaces mediated by agglutination (Slusarenko et al. 1983) or with the help of surface structures like pili (Vesper 1987); fimbriae (Vesper and Bauer 1986); exopolysaccharides like cellulose fibrils (Smit et al. 1986) and O-antigens chains of liposachharides (de Weger et al. 1989), etc. Possession of these feature(s) thus improves the probability of successful colonization by manifolds. Ability of the introduced strain to generate phenotypically diverse population with the help of site-specific recombinases (Granero et al. 2005) and to produce antibiotics (Mazzola et al. 1992) also influence the ecological competence. ...
... It is well-recognised that most plant pathogenic fungi are relatively host specific (Wood 1976; Daly 1979; Agrios 2005). The term host specificity is, however, reserved for species that derive their nutrition from live host plants. ...
... There was a significant positive correlation between the concentration of antioxidant compounds and the antioxidant activity measured by the reaction with the radical ABTS [36][37][38]. Along with the growth of microscopic fungi, the defense mechanisms of wood dust are activated in the form of the release of low-molecular-weight antioxidants from cells and their introduction into the metabolism of microscopic fungi [45][46][47][48]. This leads to growth inhibition, which was observed in our studies as a decrease in ERG levels. ...
... Cependant, ces dernières recèlent non seulement une activité enzymatique réduite, mais encore des inhibiteurs aquasolubles de la transéliminase.Huit jours après le début de l'incubation, la teneur en phénols est 4 fois plus forte au niveau des lésions limitées. Cependant, alors que la teneur en polyphénols des tissus infectés reste comparable à celle des témoins(Heath et Wood, 1971 a), la croissance des lésions évolutives sur folioles flottantes s'accompagne de la diffusion dans le support aqueux de composés vraisemblablement quinoniques, de couleur brune. La nécrose liée à une active macération se développe alors sans brunissement. ...
... Later, Perchepied et al. (2005) demonstrated, using a QTL analysis, that the partial resis- tance to Fom race 1.2 in melons is governed in part by shared loci, as well as by a strain specific locus. Wood (1986) suggested that genes controlling race non-specific resistance were genes for high resistance to avirulent races which retained residual minor effects in relation to the alleles of corre- sponding virulent races. Polygenic race non-specific resistance then becomes the sum of the minor "failed" resistance. ...
... In addition, amino-acid applications have also been reported to stimulate host resistance (Van Andel, 1966). Mercer et al. (1970) demonstrated that excess nutrients encourage Colletotrichum lindemuthianum to develop saprophytically with an apparent suppression of appresoria formation and thus normal pathogenic behavior. The application of nutrients on leaves has been found not only to enhance the competitive ability of natural antagonists of pathogens, but also to neutralize the effect agricultural chemicals had on the natural microbial inhabitants (Dik, 1991) Although it was suggested by other authors that B. subtilis operates solely by the production of anti-microbial substances (Lenné and Parbery 1976;Pusey and Wilson, 1984;Singh and Deverall, 1984;McKeen et al., 1986;Utkhede and Shollberg, 1986;Pusey et al., 1988;Pruvost and Luisetti, 1991), this study showed however that the production of antimicrobial substances are dependent on the availability of selective nutrients. ...
... We have not observed of secondary lesions on tissue located outside of the brown margin that will can showing their damage. Heath and Wood (1971) think that this is the maceration of enzymes that involved in the genesis of necrosis with limited sizes under effects of A. pisi and A. pinodes. According to Van Etten et al. (1989), A. pisi seems more sensitive to pisatin (main phytoalexine of pea) compared to other parasites of the same host. ...
... It was found that they produce about forty compounds, most of which are toxic to organisms. These compounds were classified into groups based on their chemical composition, and their presence on stored grains leads to a decrease in grain germination, and changes Color, weight loss, putrefaction, in addition to the possibility of excreting toxins such as Alternariol, which are chemical compounds of low molecular weight (Ballio, 1991). Which cause serious diseases for both humans and animals (Christensen and Kaufman, 1969),A. ...
... Bioavailability to plants and soil-inhabiting organisms of pesticides retained in soil is probably a major source to the food chain and an important route of exposure to humans and animals. Some recalcitrant pesticides are considered non-toxic at the concentrations found in the environment, but they can reach hazardous levels when they become biomagnified in natural food chains343536. ...
... Another type of agglutinin, which definitely does not determine spec recognition, was found by Slusarenko and Wood (1981). They isolated of the virulent strains. ...