Fusarium oxysporum | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Fungi |
Division: | Ascomycota |
Class: | Sordariomycetes |
Order: | Hypocreales |
Family: | Nectriaceae |
Genus: | Fusarium |
Species: | F. oxysporum |
Binomial name | |
Fusarium oxysporum Schlecht. emend. Snyder & Hansen | |
Fusarium oxysporum (Schlecht as emended by Snyder and Hansen), [1] an ascomycete fungus, comprises all the species, varieties and forms recognized by Wollenweber and Reinking [2] within an infrageneric grouping called section Elegans. It is part of the family Nectriaceae.
Although their predominant role in native soils may be as harmless or even beneficial plant endophytes or soil saprophytes, many strains within the F. oxysporum complex are soil borne pathogens of plants, especially in agricultural settings.
While the species, as defined by Snyder and Hansen, has been widely accepted for more than 50 years, [3] [4] more recent work indicates this taxon is actually a genetically heterogeneous polytypic morphospecies, [5] [6] whose strains represent some of the most abundant and widespread microbes of the global soil microflora. [7]
The Fot1 family of transposable elements was first discovered by Daboussi et al., 1992 in several formae speciales [8] [9] and Davière et al., 2001 and Langin et al., 2003 have since found them in most strains at copy numbers as high as 100. [8]
These diverse and adaptable fungi have been found in soils ranging from the Sonoran Desert, to tropical and temperate forest, grasslands and soils of the tundra. [10] F. oxysporum strains are ubiquitous soil inhabitants that have the ability to exist as saprophytes, and degrade lignin [11] [12] and complex carbohydrates [13] [14] [1] associated with soil debris. They are pervasive plant endophytes that can colonize plant roots [15] [16] and may even protect plants or form the basis of disease suppression. [17] [18]
Because the hosts of a given forma specialis usually are closely related, many have assumed that members of a forma specialis are also closely related and descended from a common ancestor. [19] However, results from research conducted on Fusarium oxysporum f. sp. cubense forced scientists to question these assumptions. Researchers used anonymous, single-copy restriction fragment length polymorphsims (RFLPs) to identify 10 clonal lineages from a collection of F. oxysporum f.sp. cubense from across the world. These results showed that pathogens of banana causing Panama disease could be as closely related to other host's pathogens, such as melon or tomato, as they are to each other. Exceptional amounts of genetic diversity within F. oxysporum f.sp. cubense were deduced from the high level of chromosomal polymorphisms found among strains, random amplified polymorphic DNA fingerprints and from the number and geographic distribution of vegetative compatibility groups. [20]
Presented with the wide-ranging occurrence of F. oxysporum strains that are nonpathogenic, it is reasonable to conclude that certain pathogenic forms were descended from originally nonpathogenic ancestors. Given the association of these fungi with plant roots, a form that is able to grow beyond the cortex and into the xylem could exploit this ability and hopefully gain an advantage over fungi that are restricted to the cortex.[ citation needed ]
The progression of a fungus into vascular tissue may elicit an immediate host response, successfully restricting the invader; or an otherwise ineffective or delayed response, reducing the vital water-conducting capacity and induce wilting. [21] On the other hand, the plant might be able to tolerate limited growth of the fungus within xylem vessels, preceded by an endophytic association. [22] In this case, any further changes in the host or parasite could disturb the relationship, in a way that fungal activities or a host response would result in the generation of disease symptoms.
Pathogenic strains of F. oxysporum have been studied for more than 100 years. The host range of these fungi is broad and includes animals, ranging from arthropods [23] to humans, [24] as well as plants, including a range of both gymnosperms and angiosperms. While collectively, plant pathogenic F. oxysporum strains have a broad host range, individual isolates usually cause disease only in a narrow range of plant species. This observation has led to the idea of "special form" or forma specialis in F. oxysporum. Formae speciales have been defined as "…an informal rank in Classification… used for parasitic fungi characterized from a physiological standpoint (e.g. by the ability to cause disease in particular hosts) but scarcely or not at all from a morphological standpoint." Exhaustive host range studies have been conducted for relatively few formae speciales of F. oxysporum. [25] For more information on Fusarium oxysporum as a plant pathogen, see Fusarium wilt and Koa wilt.
Different strains of F. oxysporum have been used for the purpose of producing nanomaterials (especially Silver nanoparticles).
In 2000, the government of Colombia proposed dispersing strains of Crivellia and Fusarium oxysporum, also known as Agent Green, as a biological weapon to forcibly eradicate coca and other illegal crops. [26] [ self-published source? ] The weaponized strains were developed by the US government, who originally conditioned their approval of Plan Colombia on the use of this weapon, but ultimately withdrew the condition. [27] In February 2001, the EU Parliament issued a declaration specifically against the use of these biological agents in warfare. [27]
The fungus has the ability to dissolve gold, then precipitate it onto its surface, encrusting itself with gold. This phenomenon was first observed in Boddington, West Australia. [28] As a result of this discovery, F. oxysporum is currently being evaluated as a possible way to help detect hidden underground gold reserves. [29] It also is used to manufacture gold nanoparticles. [30]
Fusarium wilt is a common vascular wilt fungal disease, exhibiting symptoms similar to Verticillium wilt. This disease has been investigated extensively since the early years of this century. The pathogen that causes Fusarium wilt is Fusarium oxysporum. The species is further divided into formae speciales based on host plant.
Panama disease is a plant disease that infects banana plants. It is a wilting disease caused by the fungus Fusarium oxysporum f. sp. cubense (Foc). The pathogen is resistant to fungicides and its control is limited to phytosanitary measures.
Fusarium is a large genus of filamentous fungi, part of a group often referred to as hyphomycetes, widely distributed in soil and associated with plants. Most species are harmless saprobes, and are relatively abundant members of the soil microbial community. Some species produce mycotoxins in cereal crops that can affect human and animal health if they enter the food chain. The main toxins produced by these Fusarium species are fumonisins and trichothecenes. Despite most species apparently being harmless, some Fusarium species and subspecific groups are among the most important fungal pathogens of plants and animals.
Nufar basil is the first variety of sweet basil that is resistant to fusarium wilt. Fusarium wilt is a disease that causes sudden wilting and death in multiple species, including basil. It is caused by the fungus Fusarium oxysporum f. sp. basilicum, which attacks the xylem in the stem, blocking water uptake and leading to a characteristic sudden leaf wilt that does not respond to watering. Nufar basil is resistant to fusarium wilt, remaining asymptomatic even when infected. It was released in 1999 in Israel by the breeders of the Agricultural Research Organization, and commercialized by Genesis Seeds.
Rhizoctonia solani is a species of fungus in the order Cantharellales. Basidiocarps are thin, effused, and web-like, but the fungus is more typically encountered in its anamorphic state, as hyphae and sclerotia. The name Rhizoctonia solani is currently applied to a complex of related species that await further research. In its wide sense, Rhizoctonia solani is a facultative plant pathogen with a wide host range and worldwide distribution. It causes various plant diseases such as root rot, damping off, and wire stem. It can also form mycorrhizal associations with orchids.
Thielaviopsis basicola is the plant-pathogen fungus responsible for black root rot disease. This particular disease has a large host range, affecting woody ornamentals, herbaceous ornamentals, agronomic crops, and even vegetable crops. Examples of susceptible hosts include petunia, pansy, poinsettia, tobacco, cotton, carrot, lettuce, tomato, and others. Symptoms of this disease resemble nutrient deficiency but are truly a result of the decaying root systems of plants. Common symptoms include chlorotic lower foliage, yellowing of plant, stunting or wilting, and black lesions along the roots. The lesions along the roots may appear red at first, getting darker and turning black as the disease progresses. Black root lesions that begin in the middle of a root can also spread further along the roots in either direction. Due to the nature of the pathogen, the disease can easily be identified by the black lesions along the roots, especially when compared to healthy roots. The black lesions that appear along the roots are a result of the formation of chlamydospores, resting spores of the fungus that contribute to its pathogenicity. The chlamydospores are a dark brown-black color and cause the "discoloration" of the roots when they are produced in large amounts.
Verticillium dahliae is a fungal plant pathogen. It causes verticillium wilt in many plant species, causing leaves to curl and discolor. It may cause death in some plants. Over 400 plant species are affected by Verticillium complex.
Fusarium oxysporum f.sp. albedinis is a fungal plant pathogen that causes a disease known as Bayoud disease or fusarium wilt primarily on date palm.
Fusarium oxysporum f.sp. betae is a destructive fungal plant pathogen. It causes Fusarium yellows or fusarium wilt, characterized by yellowing and dwarfing.
Fusarium redolens is a species of fungus in the genus Fusarium and family Nectriaceae. This species is a soil-borne plant pathogen in temperate prairies. It causes diseases such as root, crown, and spear rot, seedling damping-off, and wilting disease. It is a known producer of the alkaloids peimisine and imperialine-3β-d-glucoside, which has implications for traditional Chinese medicine.
Fusarium solani is a species complex of at least 26 closely related filamentous fungi in the division Ascomycota, family Nectriaceae. It is the anamorph of Nectria haematococca. It is a common soil fungus and colonist of plant materials. Fusarium solani is implicated in plant diseases as well as in serious human diseases such as fungal keratitis.
Black rot, caused by the bacterium Xanthomonas campestris pv. campestris (Xcc), is considered the most important and most destructive disease of crucifers, infecting all cultivated varieties of brassicas worldwide. This disease was first described by botanist and entomologist Harrison Garman in Lexington, Kentucky, US in 1889. Since then, it has been found in nearly every country in which vegetable brassicas are commercially cultivated.
Fusarium oxysporum f. sp. cubense is a fungal plant pathogen that causes Panama disease of banana, also known as Fusarium wilt. The fungi and the related disease are responsible for widespread pressure on banana growing regions, destroying the economic viability of several commercially important banana varieties.
Fusarium circinatum is a fungal plant pathogen that causes the serious disease pitch canker on pine trees and Douglas firs. The most common hosts of the pathogen include slash pine, loblolly pine, Monterey pine, Mexican weeping pine, and Douglas fir. Like other Fusarium species in the phylum Ascomycota, it is the asexual reproductive state of the fungus and has a teleomorph, Gibberella circinata.
Bayoud disease is an epiphytic fungal disease of date palm. The pathogen responsible for the disease is Fusarium oxysporum f.sp. albedinis.
Koa wilt is a relatively new disease to Hawaii, discovered in 1980. Koa wilt is caused by a forma specialis of the fungus Fusarium oxysporum, which is now abundant in Hawaiian soils and infects the native Acacia koa tree, a once-dominant species in the canopy of Hawaiian forests. Fusarium oxysporum f.sp. koae is believed to have been brought into Hawaii on an ornamental acacia plant. Fusarium fungi clog the tree xylem, causing significant wilt and mortality among these beautiful and iconic Hawaiian trees.
Robert S. Dickey was an American phytopathologist, professor emeritus of Plant Pathology at the Cornell University and the namesake of the bacterial genus Dickeya.
Aspergillus giganteus is a species of fungus in the genus Aspergillus that grows as a mold. It was first described in 1901 by Wehmer, and is one of six Aspergillus species from the Clavati section of the subgenus Fumigati. Its closest taxonomic relatives are Aspergillus rhizopodus and Aspergillus longivescia.
Hemibiotrophs are the spectrum of plant pathogens, including bacteria, oomycete and a group of plant pathogenic fungi that keep its host alive while establishing itself within the host tissue, taking up the nutrients with brief biotrophic-like phase. It then, in later stages of infection switches to a necrotrophic life-style, where it rampantly kills the host cells, deriving its nutrients from the dead tissues.
Fungal effectors are proteins or non-proteinaceous molecules secreted by pathogenic fungi into a host organism in order to modulate the host's immune response.