**3. Pathology**

The members of genus *Fusarium* can incite diseases in plants, animals, and humans [23]. The mortality rate for human patients with systemic *Fusarium* infection is reported to be greater than 70% [24]. In addition, *Fusarium* species produce secondary metabolites that are associated with plant diseases, as well as with diseases of animals and humans [25, 26]. In this chapter, only *Fusarium* diseases in plants will be discussed.

*Fusarium* has been known for over 200 years. Despite universal effort on developing effective management of *Fusarium* in plants, *Fusarium* diseases continue to be among the most important plant diseases. *Fusarium* species are among the most widespread fungi in the world and are of great economic importance. Many plant species are affected with at least one *Fusarium* disease [3, 4]. The American Phytopathological Society reported that 81 of 101 economically important plants have at least one *Fusarium* disease (www.apsnet.or/ online/common/search.asp). To understand importance of *Fusarium* diseases in plants, **Table 1** was prepared that shows *Fusarium* species, their host plants, and geographical distributions.

countries in his studies and evaluated their taxonomic and mycotoxicological issues. His work was published as a monograph "*Fusarium* Species: Their Biology and Toxicology" [20]. His taxonomic approach was based on the taxonomic systems of Wollenweber and Reinking

16 Fusarium - Plant Diseases, Pathogen Diversity, Genetic Diversity, Resistance and Molecular Markers

Toussoun and Nelson from the United States published a pictorial guide for identification of *Fusarium* species, in which 9 species and 10 cultivars were described [21]. In 1983, Nelson and Toussoun together with W. F. O. Marasas from South Africa published an illustrated manual of *Fusarium* species and described 46 species [22]. 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.

During 1980s, *Fusarium* taxonomists, 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 *Fusarium* taxonomy based on fungal morphological characteristics. In 1990s, however, the application of phylogenic species concept to DNA sequencing resulted in introducing new species of *Fusarium* that often cannot be distinguished morphologically. Thus, the relatively unique uniformity of 1980s shifted

In 2006, Leslie from the United States and Summerell from Australia integrated the morphological, biological, and phylogenic species concepts and published "The *Fusarium* Laboratory Manual" with 70 species [3]. This manual, which is based on the outcomes of workshops conducted at the Kansas State University, is widely used by mycologists and plant pathologists

Although taxonomy of *Fusarium* species has been historically a complex issue, and no unanimous agreement available among the *Fusarium* taxonomists, using morphological characteristics combined by the molecular data minimizes differences in identification of *Fusarium* isolates. As more information is generated, more accurate taxonomic systems are expected to

The members of genus *Fusarium* can incite diseases in plants, animals, and humans [23]. The mortality rate for human patients with systemic *Fusarium* infection is reported to be greater than 70% [24]. In addition, *Fusarium* species produce secondary metabolites that are associated with plant diseases, as well as with diseases of animals and humans [25, 26]. In this

[2] and Gerlach and Nirenberg [19].

**2.11. Nelson, Toussoun and Marasas**

toward another chaos on *Fusarium* taxonomy.

be developed for the identification of species of *Fusarium*.

chapter, only *Fusarium* diseases in plants will be discussed.

**2.12. 1980s and 1990s**

**2.13. Leslie and Summerell**

to identify *Fusarium* isolates.

**3. Pathology**



barley, corn, oat, sorghum, and wheat. *Fusarium* causes 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

*Fusarium*: Historical and Continued Importance http://dx.doi.org/10.5772/intechopen.74147 19

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 [32]. Moreover, zearalenone has also been

Fumonisins are hydroxylated long-chain alkylamines esterified with propanetricarboxylic acid moieties produced by *Fusarium moniliforme* worldwide [33, 34]. The fumonisins have been reported carcinogenic in laboratory rats. It has also been reported that consumption of corn contaminated with *Fusarium moniliforme* is 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 *Fusarium* species 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 *Fusarium* spp. [35]. 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 [35]. In addition, this toxin causes intoxication, and the lesions include intestinal hemor-

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 *Trichothecium* species from which the first of these related compounds was isolated [28]. Trichothecenes belong to sesquiterpene compounds. They are produced on many different grains, e.g., corn, oats, and wheat by various *Fusarium* species 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 [28]. In addition, T-2 mycotoxins are also substances for biological

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 [39] 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

shown to be hepatotoxic, hematotoxic, immunotoxic, and genotoxic.

rhage, muscle weakness, breathing difficulty, cyanosis, coma, and death.

warfare that can be absorbed through a person's skin [37].

in Russia consumed cereals that overwintered in the field [38, 39].

feed stuffs including cereal grains [5, 28].

Source: The *Fusarium* Laboratory Manual [3].

**Table 1.** Plant pathogen *Fusarium species*, their host, and geographic distribution.
