The genus Fusariumwas introduced by Link in 1809 . However, Fusariumreceived more attention when “Die Fusarien” was published by Wollenweber and Reinking in 1935 . In the past 80 years, tremendous investigations have been carried out on the taxonomy, biology, and mycotoxins of Fusariumspecies [3, 4, 5]. Although Wollenweber and Reinking described 65 species, 55 varieties, and 22 forms of Fusariumin 1935 , Snyder and Hansen reduced number of species of Fusariumto nine . During 1940–1980, several mycologists developed different taxonomy of Fusarium, but none of them received a global agreement. During 1980s, Fusariumtaxonomists in the world collaborated to offer a unique agreement on Fusariumtaxonomy. In 1990s, however, the application of phylogenic species concept based on the DNA sequencing resulted in introducing new species of Fusariumthat often cannot be distinguished morphologically. In 2006, Leslie and Summerell published “The FusariumLaboratory Manual” and described 70 Fusariumspecies .
Fusariumspecies are among the most common and widespread plant pathogens in the world and are of great economic importance . Every plant pathologist, mycologist, agronomist, and horticulturist encounters them in the course of work. They are serious pathogens on a wide range of crops. In spite of worldwide investigations on Fusariumin the past 200 years, Fusariumdiseases continue to be among most important plant diseases and cause widespread crop losses throughout the world [4, 7].
Several Fusariumspecies produce mycotoxins, which cause various disorders, including cancer in animals and humans . Zearalenone, fumonisin, moniliformin, and trichothecenes are among most important Fusariummycotoxins, especially in grains . The objective of this chapter is to provide details of Fusariumtaxonomy, pathology, and mycotoxins.
The genus Fusariumwas introduced in 1809 . During 1809–1935, much of the works on Fusariumwere focused on identification of Fusariumspecies and diagnosis of Fusariumdiseases. In the past 100 years, the taxonomy of Fusariumhas undergone a number of changes, which is adapted and “The FusariumLaboratory Manual” .
2.1. Wollenweber and Reinking
The basis for all modern taxonomic systems of Fusariumspecies is the work of Wollenweber and Reinking, which was published in “Die Fusarien” in Germany. In this publication, 16 sections, 65 species, 55 varieties, and 22 forms of Fusariumwere introduced, which were separated based on the morphological differences . Prior to this publication, about a thousand Fusariumspecies had been described, often a different species for every host. Wollenweber and Reinking offered an order to a chaotic situation of Fusariumtaxonomy. In their taxonomic system, each section contained species that were united by critical morphological characteristics (e.g., macroconidia morphology and pigment). Each section contained only a few species. Other taxonomists used the sections created by Wollenweber and Reinking to develop their taxonomic systems.
2.2. Snyder and Hansen
During 1940s and 1950s, Snyder and Hansen in the United Sates (US) developed a new taxonomy system and reduced number of species of Fusariumto nine [6, 8, 9]. Their identification was based on using cultures derived from single spores. The Snyder and Hansen species taxonomy was easy to use and identify any Fusariumisolate to species level.
Gordon published a number of papers on Fusariumspecies collected from Canada [10, 11, 12]. He used Fusariumtaxonomy system developed by Wollenweber and Reinking with some concepts of Snyder and Hansen system.
2.4. Messiaen and Cassini
These French scientists developed a Fusariumtaxonomy system based on Snyder and Hansen system . They used varieties for the subspecific level instead of cultivars, which was used by Snyder and Hanson.
Matuo was a Japanese scientist who used the system developed by Snyder and Hanson and introduced a new Fusariumtaxonomy system with 10 species .
Raillo, a Russian scientist, published a taxonomic system based on the shape of macroconidia, and the presence of microconidia and chlamydospores .
Bilai, a Ukrainian scientist, studied variability in characteristics related to temperature, moisture, and culture media composition and offered her own revision of the taxonomy of the genus Fusariumand recommended combining some sections suggested by Wollenweber and Reinking [16, 17].
A significant development in the taxonomy of Fusariumwas made by Booth from England during 1960s and 1970s. He published a monograph “The Genus Fusarium” , which was a revision of the Wollenweber and Reinking’s system. Booth introduced the use of the morphology of the conidiogenous cells, especially those producing the macroconidia.
2.9. Gerlach and Nirenberg
Based on the taxonomy published in “Die Fusarien,” Gerlach and Nirenberg published their own Fusariumtaxonomy system in Germany in 1982 . In spite of the criticism of their taxonomic system, their work was a significant step forward in understanding of Fusariumtaxonomy and many of the suggested species in their system are now accepted.
Joffe, originally a Russian scientist and then in Israel, began his studies on Fusariumin Russia in 1940s. He included Fusariumisolates collected from Russia, Israel, and some other countries in his studies and evaluated their taxonomic and mycotoxicological issues. His work was published as a monograph “FusariumSpecies: Their Biology and Toxicology” . His taxonomic approach was based on the taxonomic systems of Wollenweber and Reinking  and Gerlach and Nirenberg .
2.11. Nelson, Toussoun and Marasas
Toussoun and Nelson from the United States published a pictorial guide for identification of Fusariumspecies, in which 9 species and 10 cultivars were described . In 1983, Nelson and Toussoun together with W. F. O. Marasas from South Africa published an illustrated manual of Fusariumspecies and described 46 species . Their taxonomic approach began a definitive shift toward a more complicated taxonomy and a larger set of recognized species and away from the nine species of Snyder and Hansen system. This manual has been widely used by scientists.
2.12. 1980s and 1990s
During 1980s, Fusariumtaxonomists, including Burgess and Summerell from Australia, Gerlach and Nirenberg from Germany, Marasas from South Africa, and Nelson and Toussoun from the US collaborated to offer a unique agreement on Fusariumtaxonomy based on fungal morphological characteristics. In 1990s, however, the application of phylogenic species concept to DNA sequencing resulted in introducing new species of Fusariumthat often cannot be distinguished morphologically. Thus, the relatively unique uniformity of 1980s shifted toward another chaos on Fusariumtaxonomy.
2.13. Leslie and Summerell
In 2006, Leslie from the United States and Summerell from Australia integrated the morphological, biological, and phylogenic species concepts and published “The FusariumLaboratory Manual” with 70 species . This manual, which is based on the outcomes of workshops conducted at the Kansas State University, is widely used by mycologists and plant pathologists to identify Fusariumisolates.
Although taxonomy of Fusariumspecies has been historically a complex issue, and no unanimous agreement available among the Fusariumtaxonomists, using morphological characteristics combined by the molecular data minimizes differences in identification of Fusariumisolates. As more information is generated, more accurate taxonomic systems are expected to be developed for the identification of species of Fusarium.
The members of genus Fusariumcan incite diseases in plants, animals, and humans . The mortality rate for human patients with systemic Fusariuminfection is reported to be greater than 70% . In addition, Fusariumspecies produce secondary metabolites that are associated with plant diseases, as well as with diseases of animals and humans [25, 26]. In this chapter, only Fusariumdiseases in plants will be discussed.
Fusariumhas been known for over 200 years. Despite universal effort on developing effective management of Fusariumin plants, Fusariumdiseases continue to be among the most important plant diseases. Fusariumspecies are among the most widespread fungi in the world and are of great economic importance. Many plant species are affected with at least one Fusariumdisease [3, 4]. The American Phytopathological Society reported that 81 of 101 economically important plants have at least one Fusariumdisease (www.apsnet.or/online/common/search.asp). To understand importance of Fusariumdiseases in plants, Table 1 was prepared that shows Fusariumspecies, their host plants, and geographical distributions.
|Fusariumspecies||Host plants||Geographic distribution|
|F. acuminatum||Legumes||Temperate regions|
|F. andiyazi||Sorghum||Africa, Australia, US|
|F. anthophilum||Many plant species||Temperate regions|
|F. avenaceum||Carnations, cereals, legumes||Temperate regions|
|F. brevicatenulatum||Millet, Striga asiatica||Africa|
|F. bulbicola||Bulb plant species||Europe|
|F. camptoceras||Banana, cacao||Tropical and subtropical regions|
|F. circinatum||Conifers||Chile, Japan, Mexico, South Africa, US|
|F. concentricum||Musaspecies||Central America|
|F. crookwellense||Potato, cereals||Temperate regions|
|F. culmorum||Cereals||Temperate regions|
|F. decemcellulare||Trees||Tropical regions|
|F. denticulatum||Sweet potato||Brazil, Cuba, Indonesia, US, Zambia|
|F. foetens||Begoniaspecies||Germany, Netherlands|
|F. fujikuroi||Rice||Rice-growing areas|
|F. globosum||Corn, wheat||Africa, Japan|
|F. graminearum||Barley, corn, wheat||Worldwide|
|F. guttiforme||Pineapple||Cuba, South America|
|F. heterosporum||Millet, other grasses||Africa|
|F. hostae||Hostaspecies||South Africa, US|
|F. lateritium||Woody plants||Worldwide|
|F. mangiferae||Mango||Africa, Asia, US|
|F. napiforme||Millet, sorghum||Africa, Argentina, Australia|
|F. nelsonii||Alfalfa, sorghum||South Africa|
|F. nisikadoi||Bamboo, wheat||Japan|
|F. nygamai||Sorghum||Arid regions|
|F. oxysporum||Many plant species||Worldwide|
|F. phyllophilum||Dracaenaand Sansevieriaspecies||Europe, Japan|
|F. polyphialidicum||Sorghum grain||Australia, Italy, South Africa|
|F. proliferatum||Asparagus, corn, mango, sorghum||Worldwide|
|F. pseudoanthophilum||Corn||Southern Africa|
|F. pseudograminearum||Barley, triticale, wheat||Drier areas worldwide|
|F. pseudonygamai||Pearl millet||Africa, US|
|F. ramigenum||Ficus carica||US|
|F. redolens||Many hosts||Temperate regions|
|F. sacchari||Corn, sugarcane||Mexico, Philippines|
|F. semitectum||Banana||Subtropical regions|
|F. solani||Many plant species||Worldwide|
|F. sterilihyphosum||Mango||South Africa|
|F. subglutinans||Corn||Cooler corn-growing areas|
|F. succisae||Succisa pratensis||Europe|
|F. thapsinum||Sorghum||All sorghum-growing areas|
|F. torulosum||Several plant species||Temperate regions|
|F. udum||Pigeon pea||Southern Asia, sub-Saharan of Africa|
|F. venenatum||Several plant species||Europe|
Plant pathogen Fusarium species, their host, and geographic distribution.
Source: The FusariumLaboratory Manual .
Mycotoxins are toxic secondary metabolites produced by fungi and are capable of causing diseases in both animals and humans. Mycotoxins may produce birth defects, abortion, tremors, and cancers [27, 28, 29, 30]. Among the major mycotoxin-producing fungi are Aspergillus, Claviceps, Fusarium, and Penicilliumspecies [27, 28]. Fusariumfungi are the most widespread in cereal-growing areas of the world and produce a diversity of mycotoxin types. The most prevalent Fusariumtoxins are zearalenone, fumonisin, moniliformin, and trichothecenes (T-2/HT-2 toxin, deoxynivalenol, diacetoxyscirpenol, nivalenol) [5, 28, 30, 31].
Zearalenone is a group of estrogenic metabolites produced by several species of Fusarium, the most known of which is F. graminearum[5, 28]. Zearalenone is the generic name for a complex macrocyclic molecule and is derived from the perfect stage of the fungus F. graminearum(Gibberella zeae) . Fusariuminfection and zearalenone production are most notable on barley, corn, oat, sorghum, and wheat. Fusariumcauses crown rot of corn, and scab of barley, oat, and wheat. Zearalenone is produced in infected plants in the field and in stored food and feed stuffs including cereal grains [5, 28].
Zearalenone is frequently implicated in reproductive disorders of farm animals and occasionally in hyperoestrogenic syndromes in humans [28, 32]. It has been reported that zearalenone possess estrogenic activity in cattle, pigs, and sheep. The biotransformation for zearalenone in animals involves the formation of two metabolites α-zearalenol and β-zearalenol, which are subsequently conjugated with glucuronic acid . Moreover, zearalenone has also been shown to be hepatotoxic, hematotoxic, immunotoxic, and genotoxic.
Fumonisins are hydroxylated long-chain alkylamines esterified with propanetricarboxylic acid moieties produced by Fusarium moniliformeworldwide [33, 34]. The fumonisins have been reported carcinogenic in laboratory rats. It has also been reported that consumption of corn contaminated with Fusarium moniliformeis associated with higher than average incidence of esophageal cancer, and fumonisins may be responsible. Fumonisins are structurally similar to sphingosine and may exert their biological activity through their ability to block key enzymes (sphinganine- and sphingosine-N-acyltransferases) involved in sphingolipid biosynthesis.
Moniliformin is produced by several Fusariumspecies on cereals worldwide [31, 35]. Moniliformin is a small and ionic molecule that forms only a single sensitive fragment ion in the collision cell of a tandem mass spectrometer. There is great variability in the moniliformin synthesized by Fusariumspp. . It has been reported that moniliformin in large amounts acts at the level of sugar metabolism and is cytotoxic at high concentrations in mammalian cells . In addition, this toxin causes intoxication, and the lesions include intestinal hemorrhage, muscle weakness, breathing difficulty, cyanosis, coma, and death.
Trichothecenes are a very large group of mycotoxins produced by various species of Fusarium, Cephalosporium, Myrothecium, Stachybotrys, Trichoderma, Trichothecium, and Verticimonosporium. The generic name “trichothecene” has been derived from a Trichotheciumspecies from which the first of these related compounds was isolated . Trichothecenes belong to sesquiterpene compounds. They are produced on many different grains, e.g., corn, oats, and wheat by various Fusariumspecies such as F. graminearum, F. poae, and F. sporotrichioides[28, 36, 37].
There are several types of trichothecene mycotoxins, including deoxynivalenol, diacetoxyscirpenol, HT-2 mycotoxins, neosolaniol, nivalenol, satratoxin-H, T-2 mycotoxins, verrucarin A, and vomitoxin. Exposure to trichothecene mycotoxins can cause different symptoms in people such as dry eyes, tiredness, fatigue, vomiting, diarrhea, abdominal pain, mental impairment, rash, and bleeding . In addition, T-2 mycotoxins are also substances for biological warfare that can be absorbed through a person’s skin .
Trichothecenes are typically found in plants when the autumn is cool and wet that delays harvest of grains such as corn. The toxins are also found in animal feeds that contain contaminated grain with Fusarium. Joffe  reported that trichothecenes are among the most toxic mycotoxins. He found that the LD50 rate for laboratory mice given trichothecene mycotoxins is between 1 and 7 mg/kg, depending on the specific type of trichothecene and the method of exposure [38, 39]. Toxicity of trichothecene in human is documented since 1913 when people in Russia consumed cereals that overwintered in the field [38, 39].
After about 200 years from the first introduction of Fusarium, there is not a universal agreement on the taxonomy of Fusariumspecies yet. However, considerable efforts are underway to use the available information to develop a uniform taxonomy system for Fusarium. Fusariumspecies infect most of plant species and cause substantial crop and yield losses. Effective management of Fusariumdiseases in crops is not only essential for preventing crop losses but also needed to minimize mycotoxin production in food and feed products. Major strategies for preventing/minimizing mycotoxin production should be based on preventing growth of Fusariumin plants and therefore mycotoxin formation, reducing or eliminating mycotoxins from contaminated food and feed stuffs, or diverting contaminated products to low risk uses.