Keith Graham Davies

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Verified

Keith verified their affiliation via an institutional email.

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• BSc PhD
• Professor (Associate) at University of Hertfordshire

A new humoral factor has been detected, within a project aiming to disclose the bodys reproductive hormonal brake against tissue overgrowth, micrin ("my-crin"). It is hypothesized that micrin braking, gonadal and hypothalamic, is lifted at puberty and wanes with age, bringing on prostatic enlargement and cancers. Factor purification has involved fr...

Populations of Pasteuria penetrans isolated from root-knot nematodes ( Meloidogyne spp.) and cyst nematodes ( Heterodera spp.) were tested for their ability to adhere to a limited selection of sheathed and exsheathed animal parasitic nematodes, free living nematodes, including Caenorhabditis elegans wild type and several srf mutants, and plant para...

Plant-parasitic nematodes are important economic pests of a range of tropical crops. Strategies for managing these pests have relied on a range of approaches, including crop rotation, the utilization of genetic resistance, cultural techniques, and since the 1950’s the use of nematicides. Although nematicides have been hugely successful in controlli...

Since the beginning of the Enlightenment science and its application have remade our world. This change has been built on a concurrent change in our values and sensibility by which the idea of progress evolved and replaced the idea of providence associated with the increasing sovereignty of reason. Although this has over time proved beneficial to l...

Selected strains of Pasteuria species from the endospore-forming Gram-positive bacteria group have the potential to be developed into control agents for plant-parasitic nematodes. If Pasteuria is to be deployed successfully as a control agent, endospores of the bacterium initially have to adhere to the cuticle of the infective juvenile. Studies of...

Plant-parasitic nematodes (PPN) are an economically important group of crop pests and are oviparous animals; all nutrients required to develop and ensure the survival of their unhatched progeny need to be deposited within the egg, including proteins. The most abundant protein deposited is vitellin, formed of a precursor protein vitellogenin, which...

Background Biopurification has been used to disclose an evolutionarily conserved inhibitory reproductive hormone involved in tissue mass determination. A (rat) bioassay-guided physicochemical fractionation using ovine materials yielded via Edman degradation a 14-residue amino acid (aa) sequence. As a 14mer synthetic peptide (EPL001) this displayed...

Aims: Phytonematodes are a constraint on crop production and have been controlled using nematicides; these are highly toxic and legislation in Europe and elsewhere is prohibiting their use and alternatives are being sought. Pasteuria penetrans is a hyperparasitic bacterium that form endospores and have potential to control root-knot nematodes (Mel...

Cysts of Heterodera cajani was characterized via molecular analysis using D2-D3 region of 28S ribosomal DNA (rDNA). BlastN analysis of the amplified fragment in NCBI database revealed that H.cajani IARI isolate showed 100% similarity with H.cajani isolate 252 (Accession No. DQ328693). The phylogenetic relations of H. cajani were evaluated by neighb...

Increased reproduction (x3) of the entomopathogenic nematode Steinernema siamkayai occurred when exposed to one synthetic peptide (IEPVFT), while the fecundity of worms exposed to hexamer (KLKMNG) was reduced (x0.5). These hexamers were opposite ends of a 14 amino acid (aa) synthetic peptide KLKMNGKNIEPVFT (EPL030). The bioactivity of the hexamers...

An isolate of Heterodera cajani Pasteuria (HcP) was characterized for its genetic lineage and host specificity. The 16S rDNA characterization of the isolate showed 98% identity with another HcP isolate (Accession No. JN 592479) and 97% identity with P. nishizawae isolates. In the host range studies, an average of 14, 2.5 and 13.6 spores adhered to...

Soils and plant root rhizospheres have diverse microorganism profiles. Components of this naturally occurring microbiome, arbuscular mycorrhizal (AM) fungi and plant growth promoting rhizobacteria (PGPR), may be beneficial to plant growth. Supplementary application to host plants of AM fungi and PGPR either as single species or multiple species ino...

Arbuscular Mycorrhizal (AM) fungi form mutualistic symbiotic relationships with approximately 80% of terrestrial plant species, while producing the glycoprotein glomalin as a structural support molecule along their mycelial network. Glomalin confers two benefits for soils: (1) acting as a carbon and nitrogen storage molecule; (2) the binding of soi...

Silicon is found in all plants and the accumulation of silicon can improve plant tolerance to biotic stress. Strawberry powdery mildew (Podosphaera aphanis) and two-spotted spider mite (Tetranychus urticae) are both detrimental to strawberry production worldwide. Two field trials were done on a UK commercial strawberry farm in 2014 and 2015, to ass...

Arbuscular mycorrhizal (AM) fungi establish close interactions with host plants, an estimated 80% of vascular plant species. The host plant receives additional soil bound nutrients that would otherwise not be available. Other components of the microbiome, such as rhizobacteria, may influence interactions between AM fungi and the host plant. Within...

Zero till cropping systems typically apply broad-spectrum herbicides such as glyphosate as an alternative weed control strategy to the physical inversion of the soil provided by cultivation. Glyphosate targets 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase in plants. There is growing evidence that this may have a detrimental impact on non-targe...

Phytonematodes are globally important functional components of the belowground ecology in both natural and agricultural soils; they are a diverse group of which some species are economically important pests, and environmentally benign control strategies are being sought to control them. Using eco-evolutionary theory, we test the hypothesis that roo...

Pasteuria spp. are endospore forming bacteria which act as natural antagonists to many of the most economically significant plant parasitic nematodes (PPNs). Highly species-specific nematode suppression may be observed in soils containing a sufficiently high density of Pasteuria spp. spores. This suppression is enacted by the bacteria via inhibitio...

Arbuscular mycorrhizal (AM) fungi are one of the most common fungal organisms to exist in symbiosis with terrestrial plants, facilitating the growth and maintenance of arable crops. Wheat has been studied extensively for AM fungal symbiosis using the carcinogen trypan blue as the identifying stain f or fungal components, namely arbuscles, vesicles...

Background Southern root-knot nematode Meloidogyne incognita (Kofoid and White, 1919), Chitwood, 1949 is a key pest of agricultural crops. Pasteuria penetrans is a hyperparasitic bacterium capable of suppressing the nematode reproduction, and represents a typical coevolved pathogen-hyperparasite system. Attachment of Pasteuria endospores to the cut...

Pasteuria spp. belong to a group of genetically diverse endospore-forming bacteria (phylum: Firmicutes) that are known to parasitize plant-parasitic nematodes and water fleas (Daphnia spp.). Collagen-like fibres form the nap on the surface of endospores and the genes encoding these sequences have been hypothesised to be involved in the adhesion of...

Neem is a perennial plant of family Meliaceae grown very commonly in India. During a survey in Rajasthan, India; a population of root-knot nematode was found in association with tender neem plants causing yellowing, stunting, and heavy root galling. Inspection of the perineal pattern morphology of the adult females, extracted from the galled roots,...

Mucins are highly glycosylated polypeptides involved in many host parasite interactions, but their function in plant‐parasitic nematodes is still unknown. In this study, a mucin‐like gene was cloned from M. incognita (Mi‐muc‐1, 1125 bp) and characterized. The protein was found to be rich in serine and threonine content with numerous O‐glycosylation...

This book contains 17 chapters focusing on the biological, taxonomic and molecular characteristics of the plant parasitic cyst nematodes. The importance of the development of environmentally acceptable ways to manage and control these pests are also discussed.

Root-knot nematode (RKN) Meloidogyne incognita is an economically important pest of crops. Pasteuria penetrans, is a nematode hyperparasitic bacterium capable of suppressing the reproduction of RKN and thereby useful for its management. Secreted fatty acid and retinol-binding proteins are unique in nematodes and are engaged in nutrient acquisition,...

Pasteuria are a group of endospore forming bacteria with very little sequence data. This investigation uses genomes from other closely related Bacillus species to identify genes that may be involved in host infection.

The knowledge that the plant-parasitic nematode hyperparasite Pasteuria penetrans is important in nematode suppressive soils has long been recognised. The ability to mass produce this organism in vitro circumvents one of its major constraints. However, successful biological control can only be established if the strains that are deployed can attach...

By 2050, Africa's population is projected to exceed two billion. Africa will have to increase food production more than 50% in the coming 50 years to meet the nutritional requirements of its growing population. Nowhere is the need to increase agricultural productivity more pertinent than in much of sub-Saharan Africa where it is currently static or...

By 2050, Africa's population is projected to exceed 2 billion. Africa will have to increase food production more than 50% in the coming 50 years to meet the nutritional requirements of its growing population. Nowhere is the need to increase agricultural productivity more pertinent than in much of Sub-Saharan Africa, where it is currently static or...

Ambient exposure to a short synthetic peptide has enhanced fecundity (number of offspring) in invertebrates and vertebrates, ostensibly by disinhibiting reproduction. In separate experiments nematodes (Caenorhabditis elegans) and guppy fish (Poecilia reticulata) were exposed via their aqueous environment to a dissolved synthetic hexamer peptide, IE...

The Pasteuria group of Gram positive bacteria are invertebrate parasites with the potential to be developed into biological control agents of plant-parasitic nematodes. A key step in the infection process is the attachment of endospores to the cuticle of plant-parasitic nematodes, possibly through a Velcro-like attachment system involving the colla...

This book, divided into three parts, provides a wide range of information on plant-parasitic nematodes. The chapters in Part I presents the basic structures of nematodes, followed by a chapter on molecular taxonomy, systematics and phylogeny. The subsequent four chapters focus on the major groups of plant-parasitic nematodes, presenting information...

Three experiments were conducted to compare the attraction and repulsion of second-stage juveniles (J2) of the root-knot nematode, Meloidogyne graminicola, to rice plants supplied with different forms of nitrogen. The rice plants were hydroponically grown in a full nutrient solution containing different concentrations (0.1 or 10.0 mM) of nitrate (N...

European foredunes are almost exclusively colonised by Ammophila arenaria, and both the natural succession and the die-out of this plant have been linked to populations of plant-parasitic nematodes (PPN). The overarching aim of this study was to investigate top-down control processes of PPN in these natural ecosystems through comparative analyses o...

The molecular interactions between hosts and parasites is an active area of research, and the parasitism of root-knot nematodes, obligate parasites of plants, by the hyper-parasitic bacterium Pasteuria penetrans offers a model by which to investigate aspects of innate immunity. Using a pouch system we were able to demonstrate by PCR, infection of M...

The Pasteuria group of Gram-positive, endospore-forming bacteria are parasites of invertebrates and exhibit differences in host specificity. We describe a cross-infection study between an isolate of Pasteuria from pigeon pea cyst nematode, Heterodera cajani, which also infects the potato cyst nematode, Globodera pallida, from the United Kingdom. A...

Comparisons of the growth of Pasteuria penetrans in adult root-knot nematode females infected with P. penetrans dissected from the roots of tomato plants were undertaken using bright-field and scanning electron microscopy. Samples of infected females were nutritionally compromised by maintaining them in sterile saline at 30°C for different periods...

Protein-encoding and 16S rRNA genes of Pasteuria penetrans populations from a wide range of geographic locations were examined. Most interpopulation single nucleotide polymorphisms (SNPs) were detected in the 16S rRNA gene. However, in order to fully resolve all populations, these were supplemented with SNPs from protein-encoding genes in a multilo...

The outer surface of nematodes act as an external skeleton and is covered by a tough, but flexible, multi-layered, extracellular cuticle which protects them from the external environment, maintains body shape and is involved in locomotion and defence against their host or microorganism attack. This chapter highlights the role of the nematode surfac...

Caenorhabditis elegans was the first multicellular organism to have its genome sequenced and has proved useful in the investigations of innate immunity, the generic science that underpins the biology of host-pathogen interactions. This chapter explores the sequencing of plant-parasitic nematodes and microbial genomes and shows how this knowledge ca...

Since the publication of Stirling’s book (1991), our knowledge has grown but the developments of robust strategies that exploit biological control have remained, in the main, anecdotal and illusive. A new era is now present in which the research and development of biological control is the result of several circumstances: (1) The inconsistent resul...

In the search for alternatives to nematicides, biological control has always remained in the shadow of plant resistance. However, basic research on the natural enemies of nematode pests can lead to much informative knowledge on host-parasite interactions. This review looks at the historical context of the use of natural enemies to control plant-par...