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Unravelling Mycosphaerella: do you believe in genera?

Crous PW, Summerell BA, Carnegie AJ, Wingfield MJ, Hunter GC, Burgess TI, Andjic V, Barber PA, Groenewald JZ - Persoonia (2009)

Bottom Line: The genus Schizothyrium with Zygophiala anamorphs is supported as belonging to the Schizothyriaceae, while Dissoconium and Ramichloridium appear to represent a distinct family.Several clades remain unresolved due to limited sampling.Mycosphaerella, which has hitherto been used as a term of convenience to describe ascomycetes with solitary ascomata, bitunicate asci and 1-septate ascospores, represents numerous genera and several families yet to be defined in future studies.

View Article: PubMed Central - PubMed

Affiliation: CBS-KNAW Fungal Biodiversity Centre, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands;

ABSTRACT
Many fungal genera have been defined based on single characters considered to be informative at the generic level. In addition, many unrelated taxa have been aggregated in genera because they shared apparently similar morphological characters arising from adaptation to similar niches and convergent evolution. This problem is aptly illustrated in Mycosphaerella. In its broadest definition, this genus of mainly leaf infecting fungi incorporates more than 30 form genera that share similar phenotypic characters mostly associated with structures produced on plant tissue or in culture. DNA sequence data derived from the LSU gene in the present study distinguish several clades and families in what has hitherto been considered to represent the Mycosphaerellaceae. In some cases, these clades represent recognisable monophyletic lineages linked to well circumscribed anamorphs. This association is complicated, however, by the fact that morphologically similar form genera are scattered throughout the order (Capnodiales), and for some species more than one morph is expressed depending on cultural conditions and media employed for cultivation. The present study shows that Mycosphaerella s.s. should best be limited to taxa with Ramularia anamorphs, with other well defined clades in the Mycosphaerellaceae representing Cercospora, Cercosporella, Dothistroma, Lecanosticta, Phaeophleospora, Polythrincium, Pseudocercospora, Ramulispora, Septoria and Sonderhenia. The genus Teratosphaeria accommodates taxa with Kirramyces anamorphs, while other clades supported in the Teratosphaeriaceae include Baudoinea, Capnobotryella, Devriesia, Penidiella, Phaeothecoidea, Readeriella, Staninwardia and Stenella. The genus Schizothyrium with Zygophiala anamorphs is supported as belonging to the Schizothyriaceae, while Dissoconium and Ramichloridium appear to represent a distinct family. Several clades remain unresolved due to limited sampling. Mycosphaerella, which has hitherto been used as a term of convenience to describe ascomycetes with solitary ascomata, bitunicate asci and 1-septate ascospores, represents numerous genera and several families yet to be defined in future studies.

No MeSH data available.


Readeriella					eucalypti (CPC 14950). a. Colony on OA; b–e. conidiogenous cells giving rise to conidia; f–i. conidia with basal appendages; j. conidia. — Scale bars = 10 μm.
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Figure 2: Readeriella eucalypti (CPC 14950). a. Colony on OA; b–e. conidiogenous cells giving rise to conidia; f–i. conidia with basal appendages; j. conidia. — Scale bars = 10 μm.

Mentions: Crous et al. (2007a) used a wider concept for Readeriella, and recognised it as being polyphyletic within the Teratosphaeriaceae. Furthermore, based on its conidiogenesis that is very similar to that of Kirramyces, with conidiogenous cells ranging from mono- to polyphialides with periclinal thickening, to phialides with percurrent proliferation, the two genera were seen as synonymous. However, the present analysis shows that these two clades cluster apart within the Teratosphaeriaceae (Fig. 1, part 4). Although they are morphologically similar, Readeriella species have conidia that tend to have tapering subtruncate bases, and frequently form Cibiessia synanamorphs. In contrast, Kirramyces and Colletogloeopsis anamorphs have truncate conidial bases, and are never found associated with Cibiessia synanamorphs. Nothostrasseria (1983) has conidiogenesis similar to that in Readeriella, and forms conidia with basal appendages, which can also occur in Readeriella eucalypti (Fig. 2, Crous et al. 2007a). The generic name for this clade is the older name, Readeriella (1908).


Unravelling Mycosphaerella: do you believe in genera?

Crous PW, Summerell BA, Carnegie AJ, Wingfield MJ, Hunter GC, Burgess TI, Andjic V, Barber PA, Groenewald JZ - Persoonia (2009)

Readeriella					eucalypti (CPC 14950). a. Colony on OA; b–e. conidiogenous cells giving rise to conidia; f–i. conidia with basal appendages; j. conidia. — Scale bars = 10 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2802725&req=5

Figure 2: Readeriella eucalypti (CPC 14950). a. Colony on OA; b–e. conidiogenous cells giving rise to conidia; f–i. conidia with basal appendages; j. conidia. — Scale bars = 10 μm.
Mentions: Crous et al. (2007a) used a wider concept for Readeriella, and recognised it as being polyphyletic within the Teratosphaeriaceae. Furthermore, based on its conidiogenesis that is very similar to that of Kirramyces, with conidiogenous cells ranging from mono- to polyphialides with periclinal thickening, to phialides with percurrent proliferation, the two genera were seen as synonymous. However, the present analysis shows that these two clades cluster apart within the Teratosphaeriaceae (Fig. 1, part 4). Although they are morphologically similar, Readeriella species have conidia that tend to have tapering subtruncate bases, and frequently form Cibiessia synanamorphs. In contrast, Kirramyces and Colletogloeopsis anamorphs have truncate conidial bases, and are never found associated with Cibiessia synanamorphs. Nothostrasseria (1983) has conidiogenesis similar to that in Readeriella, and forms conidia with basal appendages, which can also occur in Readeriella eucalypti (Fig. 2, Crous et al. 2007a). The generic name for this clade is the older name, Readeriella (1908).

Bottom Line: The genus Schizothyrium with Zygophiala anamorphs is supported as belonging to the Schizothyriaceae, while Dissoconium and Ramichloridium appear to represent a distinct family.Several clades remain unresolved due to limited sampling.Mycosphaerella, which has hitherto been used as a term of convenience to describe ascomycetes with solitary ascomata, bitunicate asci and 1-septate ascospores, represents numerous genera and several families yet to be defined in future studies.

View Article: PubMed Central - PubMed

Affiliation: CBS-KNAW Fungal Biodiversity Centre, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands;

ABSTRACT
Many fungal genera have been defined based on single characters considered to be informative at the generic level. In addition, many unrelated taxa have been aggregated in genera because they shared apparently similar morphological characters arising from adaptation to similar niches and convergent evolution. This problem is aptly illustrated in Mycosphaerella. In its broadest definition, this genus of mainly leaf infecting fungi incorporates more than 30 form genera that share similar phenotypic characters mostly associated with structures produced on plant tissue or in culture. DNA sequence data derived from the LSU gene in the present study distinguish several clades and families in what has hitherto been considered to represent the Mycosphaerellaceae. In some cases, these clades represent recognisable monophyletic lineages linked to well circumscribed anamorphs. This association is complicated, however, by the fact that morphologically similar form genera are scattered throughout the order (Capnodiales), and for some species more than one morph is expressed depending on cultural conditions and media employed for cultivation. The present study shows that Mycosphaerella s.s. should best be limited to taxa with Ramularia anamorphs, with other well defined clades in the Mycosphaerellaceae representing Cercospora, Cercosporella, Dothistroma, Lecanosticta, Phaeophleospora, Polythrincium, Pseudocercospora, Ramulispora, Septoria and Sonderhenia. The genus Teratosphaeria accommodates taxa with Kirramyces anamorphs, while other clades supported in the Teratosphaeriaceae include Baudoinea, Capnobotryella, Devriesia, Penidiella, Phaeothecoidea, Readeriella, Staninwardia and Stenella. The genus Schizothyrium with Zygophiala anamorphs is supported as belonging to the Schizothyriaceae, while Dissoconium and Ramichloridium appear to represent a distinct family. Several clades remain unresolved due to limited sampling. Mycosphaerella, which has hitherto been used as a term of convenience to describe ascomycetes with solitary ascomata, bitunicate asci and 1-septate ascospores, represents numerous genera and several families yet to be defined in future studies.

No MeSH data available.