mainly through the consumption of contaminated food, but inhalation with the air
is also possible. Many of these compounds do not degrade during technological
processes even under high temperature and pressure conditions. Mycotoxins are
biosynthesized by fungi and secreted into host tissues where they are accumulated
and transferred into food and feedstuffs. Exposure to mycotoxins may also occur
through the consumption of contaminated animal products such as meat, milk, or
eggs because some compounds pass from plant-derived materials to animal tissues
and may be excreted with milk (e.g., aflatoxins). Numerous reports on diseases
caused by Fusarium mycotoxins are available. Fumonisins B 1 and B 2 causing
equine encephalomalacia, deoxynivalenol causing vomiting as well as diarrhea,
and zearalenone causing breast cancer are among the most frequent ones [1, 23, 24].
4
Phylogeny and New Species Discovery
Exact taxonomic positioning of the Fusarium genotype studied is one of the most
basic questions faced by researchers interested in Fusarium research, because
mistake at this stage may have serious consequences. During last decades, three
kinds of species concepts were proposed to identify Fusarium species:
– Morphological species concept (defined by the morphological characters of pure
fungal cultures on standardized laboratory media)
– Biological species concept (using sexual crosses, aggressiveness tests)
– Phylogenetical species concept (molecular analyses defining similarities between
related strains)
Sometimes, the combination of two or three of these species’ concepts can be
found [25–27]. Nevertheless, the use of morphological species concept for identifying species requires a skilled and experienced researcher with wide knowledge of
classical taxonomy, which is nowadays more and more difficult to find. Additional
problem bears in overlapping morphological characters among closely related species and new species described practically each year.
The biological characteristics based on sexual compatibility show numerous
problems, such as environmental factors suppressing sexual reproduction, unequal
frequencies of mating-type alleles in different populations, or failure of compatible
isolates to reproduce due to male or female dominance. Moreover, the environmental
conditions and genetics of the host may play significant roles in aggressiveness tests
on specific host plant [28]. According to Moretti (2009), it is a great challenge to
determine the taxonomic status of Fusarium species on the basic of their phenotypic
characteristics alone, including pathogenicity and toxigenicity [29].
After the year 2000, most scientists have utilized the molecular phylogenetic
approaches to ascertain the taxonomy of Fusarium species and have proposed new
taxonomic systems based on the phylogenetic species concept [3, 7, 10, 12, 30–35].
This was a requirement that arose from the fact that several of the “traditional”
216
Ł. Stępień et al.
is also possible. Many of these compounds do not degrade during technological
processes even under high temperature and pressure conditions. Mycotoxins are
biosynthesized by fungi and secreted into host tissues where they are accumulated
and transferred into food and feedstuffs. Exposure to mycotoxins may also occur
through the consumption of contaminated animal products such as meat, milk, or
eggs because some compounds pass from plant-derived materials to animal tissues
and may be excreted with milk (e.g., aflatoxins). Numerous reports on diseases
caused by Fusarium mycotoxins are available. Fumonisins B 1 and B 2 causing
equine encephalomalacia, deoxynivalenol causing vomiting as well as diarrhea,
and zearalenone causing breast cancer are among the most frequent ones [1, 23, 24].
4
Phylogeny and New Species Discovery
Exact taxonomic positioning of the Fusarium genotype studied is one of the most
basic questions faced by researchers interested in Fusarium research, because
mistake at this stage may have serious consequences. During last decades, three
kinds of species concepts were proposed to identify Fusarium species:
– Morphological species concept (defined by the morphological characters of pure
fungal cultures on standardized laboratory media)
– Biological species concept (using sexual crosses, aggressiveness tests)
– Phylogenetical species concept (molecular analyses defining similarities between
related strains)
Sometimes, the combination of two or three of these species’ concepts can be
found [25–27]. Nevertheless, the use of morphological species concept for identifying species requires a skilled and experienced researcher with wide knowledge of
classical taxonomy, which is nowadays more and more difficult to find. Additional
problem bears in overlapping morphological characters among closely related species and new species described practically each year.
The biological characteristics based on sexual compatibility show numerous
problems, such as environmental factors suppressing sexual reproduction, unequal
frequencies of mating-type alleles in different populations, or failure of compatible
isolates to reproduce due to male or female dominance. Moreover, the environmental
conditions and genetics of the host may play significant roles in aggressiveness tests
on specific host plant [28]. According to Moretti (2009), it is a great challenge to
determine the taxonomic status of Fusarium species on the basic of their phenotypic
characteristics alone, including pathogenicity and toxigenicity [29].
After the year 2000, most scientists have utilized the molecular phylogenetic
approaches to ascertain the taxonomy of Fusarium species and have proposed new
taxonomic systems based on the phylogenetic species concept [3, 7, 10, 12, 30–35].
This was a requirement that arose from the fact that several of the “traditional”
216
Ł. Stępień et al.