Purpureocillium lilacinum | |
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Divergent phialides and long, tangled chains of elliptical conidia borne from more complex fruiting structures characteristic of Purpureocillium lilacinum; magnification 460X. | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Fungi |
Division: | Ascomycota |
Class: | Sordariomycetes |
Order: | Hypocreales |
Family: | Ophiocordycipitaceae |
Genus: | Purpureocillium |
Species: | P. lilacinum |
Binomial name | |
Purpureocillium lilacinum (Thom) Luangsa-ard, Hou- braken, Hywel-Jones & Samson (2011) | |
Synonyms [1] | |
PaecilliumLuangsa-ard, Hywel-Jones & Samson nom. prov. (2007) [2] Contents |
Purpureocillium lilacinum is a species of filamentous fungus in the family Ophiocordycipitaceae. [3] It has been isolated from a wide range of habitats, including cultivated and uncultivated soils, forests, grassland, deserts, estuarine sediments and sewage sludge, and insects. It has also been found in nematode eggs, and occasionally from females of root-knot and cyst nematodes. In addition, it has frequently been detected in the rhizosphere of many crops. The species can grow at a wide range of temperatures – from 8 to 38 °C (46 to 100 °F) for a few isolates, with optimal growth in the range 26 to 30 °C (79 to 86 °F). It also has a wide pH tolerance and can grow on a variety of substrates. [4] [5] P. lilacinum has shown promising results for use as a biocontrol agent to control the growth of destructive root-knot nematodes.
The species was originally described by American mycologist Charles Thom in 1910, under than name Penicillium lilacinum. [6] Taxonomic synonyms include Penicillium amethystinum Wehmer and Spicaria rubidopurpurea Aoki. [1] In 1974, Robert A. Samson transferred the species to Paecilomyces . [4] Publications in the 2000s (decade) indicated that the genus Paecilomyces was not monophyletic, [7] and that close relatives were Paecilomyces nostocoides, Isaria takamizusanensis and Nomuraea atypicola. [8] The new genus Purpureocillium was created to hold the taxon. The generic name refers to the purple conidia produced by the fungus. [9]
Purpureocillium lilacinum forms a dense mycelium which gives rise to conidiophores. These bear phialides from the ends of which spores are formed in long chains. Spores germinate when suitable moisture and nutrients are available. Colonies on malt agar grow rather fast, attaining a diameter of 5–7 cm within 14 days at 25 °C (77 °F), consisting of a basal felt with a floccose overgrowth of aerial mycelium; at first white, but when sporulating changing to various shades of vinaceous. The reverse side is sometimes uncolored but usually in vinaceous shades. The vegetative hyphae are smooth-walled, hyaline, and 2.5–4.0 μm wide. Conidiophores arising from submerged hyphae, 400–600 μm in length, or arising from aerial hyphae and half as long. Phialides consisting of a swollen basal part, tapering into a thin distinct neck. Conidia are in divergent chains, ellipsoid to fusiform in shape, and smooth walled to slightly roughened. Chlamydospores are absent. [4]
Purpureocillium lilacinum is highly adaptable in its life strategy: depending on the availability of nutrients in the surrounding microenvironments it may be entomopathogenic, [10] [11] [12] mycoparasitic, [13] saprophytic, [14] as well as nematophagous.
Purpureocillium lilacinum is an infrequent cause of human disease. [15] [16] Most reported cases involve patients with compromised immune systems, indwelling foreign devices, or intraocular lens implants. [17] [18] Research of the last decade suggests it may be an emerging pathogen of both immunocompromised [19] as well as immunocompetent adults. [20] It is one of the most common species causing hyalohyphomycosis along with Paecilomyces variotii . [9]
Plant-parasitic nematodes cause significant economic losses to a wide variety of crops. Chemical control is a widely used option for plant-parasitic nematode management. However, chemical nematicides are now being reappraised in respect of environmental hazard, high costs, limited availability in many developing countries or their diminished effectiveness following repeated applications.
Purpureocillium lilacinum was first observed in association with nematode eggs in 1966 [21] and the fungus was subsequently found parasitising the eggs of Meloidogyne incognita in Peru. [22] It has now been isolated from many cyst and root-knot nematodes and from soil in many locations. [23] [24] Several successful field trials using P. lilacinum against pest nematodes were conducted in Peru. [22] The Peruvian isolate was then sent to nematologists in 46 countries for testing, as part of the International Meloidogyne project, resulting in many more field trials on a range of crops in many soil types and climates. [25] Field trials, glasshouse trials and in vitro testing of P. lilacinum continues and more isolates have been collected from soil, nematodes and occasionally from insects. Isolates vary in their pathogenicity to plant-parasitic nematodes. Some isolates are aggressive parasites while others, though morphologically indistinguishable, are less or non-pathogenic. Sometimes isolates that looked promising in vitro or in glasshouse trials have failed to provide control in the field. [26]
Many enzymes produced by P. lilacinum have been studied. A basic serine protease with biological activity against Meloidogyne hapla eggs has been identified. [27] One strain of P. lilacinum has been shown to produce proteases and a chitinase, enzymes that could weaken a nematode egg shell so as to enable a narrow infection peg to push through. [28]
Before infecting a nematode egg, P. lilacinum flattens against the egg surface and becomes closely appressed to it. P. lilacinum produces simple appressoria anywhere on the nematode egg shell either after a few hyphae grow along the egg surface, or after a network of hyphae form on the egg. The presence of appressoria appears to indicate that the egg is, or is about to be, infected. In either case, the appressorium appears the same, as a simple swelling at the end of a hypha, closely appressed to the eggshell. Adhesion between the appressorium and nematode egg surface must be strong enough to withstand the opposing force produced by the extending tip of a penetration hypha. [29] When the hypha has penetrated the egg, it rapidly destroys the juvenile within, before growing out of the now empty egg shell to produce conidiophores and to grow towards adjacent eggs.
Paecilotoxin is a mycotoxin isolated from the fungus. [30] Its significance is unknown. Khan et al. (2003) tested one strain of P. lilacinum for the production of paecilotoxin and were unable to show toxin production in that strain, suggesting that toxin synthesis may vary among isolates. [31] [32]
Root-knot nematodes are plant-parasitic nematodes from the genus Meloidogyne. They exist in soil in areas with hot climates or short winters. About 2000 plants worldwide are susceptible to infection by root-knot nematodes and they cause approximately 5% of global crop loss. Root-knot nematode larvae infect plant roots, causing the development of root-knot galls that drain the plant's photosynthate and nutrients. Infection of young plants may be lethal, while infection of mature plants causes decreased yield.
An entomopathogenic fungus is a fungus that can kill or seriously disable insects. They do not need to enter an insect's body through oral ingestion or intake; rather, they directly penetrate though the exoskeleton.
Metarhizium robertsii is a fungus that grows naturally in soils throughout the world and causes disease in various insects by acting as a parasitoid. It is a mitosporic fungus with asexual reproduction, which was formerly classified in the form class Hyphomycetes of the phylum Deuteromycota.
Paecilomyces is a genus of fungi. A number of species in this genus are plant pathogens.
Hyphomycetes are a form classification of fungi, part of what has often been referred to as fungi imperfecti, Deuteromycota, or anamorphic fungi. Hyphomycetes lack closed fruit bodies, and are often referred to as moulds. Most hyphomycetes are now assigned to the Ascomycota, on the basis of genetic connections made by life-cycle studies or by phylogenetic analysis of DNA sequences; many remain unassigned phylogenetically.
Clonostachys rosea f. rosea, also known as Gliocladium roseum, is a species of fungus in the family Bionectriaceae. It colonizes living plants as an endophyte, digests material in soil as a saprophyte and is also known as a parasite of other fungi and of nematodes. It produces a wide range of volatile organic compounds which are toxic to organisms including other fungi, bacteria, and insects, and is of interest as a biological pest control agent.
Acremonium strictum is an environmentally widespread saprotroph species found in soil, plant debris, and rotting mushrooms. Isolates have been collected in North and Central America, Asia, Europe and Egypt. A. strictum is an agent of hyalohyphomycosis and has been identified as an increasingly frequent human pathogen in immunosuppressed individuals, causing localized, disseminated and invasive infections. Although extremely rare, A. strictum can infect immunocompetent individuals, as well as neonates. Due to the growing number of infections caused by A. strictum in the past few years, the need for new medical techniques in the identification of the fungus as well as for the treatment of human infections has risen considerably.
Acrophialophora fusispora is a poorly studied ascomycete fungus found in soil, air and various plants. A. fusispora is morphologically similar to the genera Paecilomyces and Masonia, but differ in the presence of pigmented conidiophores, verticillate phialides, and frequent sympodial proliferation. Moreover, A. fusispora is distinguished by its pigmented spindle-shaped conidia, covered with spiral bands. The fungus is naturally found in soils of tropical to temperate regions. The fungus has been identified as a plant and animal pathogen, and has recently been recognized as an emerging opportunistic human pathogen. A. fusispora infection in human is rare and has few documented clinical cases, but due to the rarity of the fungus and potential misidentification, the infections may be underdiagnosed. Clinical cases of A. fusispora include cases of keratitis, pulmonary colonization and infection, and cerebral infections. The fungus also has two documented cases of infection in dogs.
Nematophagous fungi are carnivorous fungi specialized in trapping and digesting nematodes. Around 160 species are known. Species exist that live inside the nematodes from the beginning and others that catch them, mostly with glue traps or in rings, some of which constrict on contact. Some species possess both types of traps. Another technique is to stun the nematodes using toxins, a method employed by Coprinus comatus, Stropharia rugosoannulata, and the family Pleurotaceae. The habit of feeding on nematodes has arisen many times among fungi, as is demonstrated by the fact that nematophagous species are found in all major fungal groups. Nematophagous fungi can be useful in controlling those nematodes that eat crops. Purpureocillium, for example, can be used as a bio-nematicide.
Purpureocillium is a fungal genus in the Ophiocordycipitaceae family. The genus now contains at least 5 species with the type species Purpureocillium lilacinum, a common soil mold. It has been isolated from a wide range of habitats, including cultivated and uncultivated soils, forests, grassland, deserts, estuarine sediments and sewage sludge, and insects. It has also been found in nematode eggs, and occasionally from females of root-knot and cyst nematodes. In addition, it has frequently been detected in the rhizosphere of many crops. The species can grow at a wide range of temperatures – from 8 to 38 °C for a few isolates, with optimal growth in the range 26 to 30 °C. It also has a wide pH tolerance and can grow on a variety of substrates. P. lilacinum has shown promising results for use as a biocontrol agent to control the growth of destructive root-knot nematodes.
Paecilomyces variotii, also known by the name Byssochlamys spectabilis for the sexual state, is a common environmental mold from the Phylum Ascomycota. It is widespread in the environment and can be found in composts, soils and wood, as well es a common environmental contaminant in indoor air and carpet dust. Ascospores of the sexual state of P. variotii are strongly heat-resistant. As such the fungus is a common contaminant of heat-treated foods and juices. Paecilomyces variotii has been associated with a number of infective diseases of humans and animals.
Bacillus firmus is an aerobic, Gram-positive, rod-shaped species of bacteria within the genus Bacillus. It is a soil-dwelling bacterium.
Harposporium anguillulae is a member of the genus Harposporium. It is an endoparasitic nematophagous fungus that attacks nematodes and eelworms and is isolated commonly from field and agricultural soils as well as used as an experimental organism in the laboratory.
Arthrobotrys oligospora was discovered in Europe in 1850 by Georg Fresenius. A. oligospora is the model organism for interactions between fungi and nematodes. It is the most common nematode-capturing fungus, and most widespread nematode-trapping fungus in nature. It was the first species of fungi documented to actively capture nematodes.
Dactylellina haptotyla is a common soil-living fungus that develops structures to capture nematodes as nutrient source. In the presence of nematodes, spores can germinate into sticky knobs or non-constricting loops. The fungus traps nematodes with sticky knobs and non-constricting loops, then breakdown the cuticle, and penetrates the body of nematodes to obtain nutrients. For its predatory nature, Dactylellina haptotyla is also considered as nematode-trapping fungus or carnivorous fungus.
Paecilomyces marquandii is a soil-borne filamentous fungus distributed throughout temperate to tropical latitudes worldwide including forest, grassland, sewage sludge and strongly metal polluted area characterized by high tolerance in heavy metals. Simultaneous toxic action of zinc and alachlor result an increase in uptake of metal in this fungus but disrupts the cell membrane. Paecilomyces marquandii is known to parasitize the mushroom, Cuphophyllus virgineus, in the family, Hygrophoraceae. Paecilomyces marquandii is categorised as a biosafety risk group 1 in Canada and is not thought to be a significant pathogen of humans or animals.
Arthrobotrys dactyloides is a species of fungus in the family Orbiliaceae. It is nematophagous, forming loops of hypha to trap nematodes, on which it then feeds.
Mariannaea elegans an anamorphic fungus. It is mainly found on rotting wood and soil. M. elegans is not pathogenic to humans, animals, or plants.
Meristacrum is a fungal genus in the monotypic family Meristacraceae, of the order Entomophthorales. They are parasites of soil invertebrates, they typically infect nematodes, and tardigrades.
Arthrobotrys musiformis is a species of nematode catching fungi, genus Arthrobotrys. This, like other Arthrobotrys species, captures and feeds on nematodes. It is widespread, with its initial discovery being in Norfolk, Virginia. This species demonstrates promising anti-helminth potential, and is hypothesized to reduce the number of parasitic nematodes in plants and livestock as either a biocontrol or through isolating metabolites.
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