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Species concepts in Cercospora: spotting the weeds among the roses.

Groenewald JZ, Nakashima C, Nishikawa J, Shin HD, Park JH, Jama AN, Groenewald M, Braun U, Crous PW - Stud. Mycol. (2013)

Bottom Line: Some species were found to be limited to a specific host genus, whereas others were isolated from a wide host range.No single locus was found to be the ideal DNA barcode gene for the genus, and species identification needs to be based on a combination of gene loci and morphological characters.Takim., Cercospora sojina Hara.

View Article: PubMed Central - PubMed

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

ABSTRACT

Unlabelled: The genus Cercospora contains numerous important plant pathogenic fungi from a diverse range of hosts. Most species of Cercospora are known only from their morphological characters in vivo. Although the genus contains more than 5 000 names, very few cultures and associated DNA sequence data are available. In this study, 360 Cercospora isolates, obtained from 161 host species, 49 host families and 39 countries, were used to compile a molecular phylogeny. Partial sequences were derived from the internal transcribed spacer regions and intervening 5.8S nrRNA, actin, calmodulin, histone H3 and translation elongation factor 1-alpha genes. The resulting phylogenetic clades were evaluated for application of existing species names and five novel species are introduced. Eleven species are epi-, lecto- or neotypified in this study. Although existing species names were available for several clades, it was not always possible to apply North American or European names to African or Asian strains and vice versa. Some species were found to be limited to a specific host genus, whereas others were isolated from a wide host range. No single locus was found to be the ideal DNA barcode gene for the genus, and species identification needs to be based on a combination of gene loci and morphological characters. Additional primers were developed to supplement those previously published for amplification of the loci used in this study.

Taxonomic novelties: New species - Cercospora coniogrammes Crous & R.G. Shivas, Cercospora delaireae C. Nakash., Crous, U. Braun & H.D. Shin, Cercospora euphorbiae-sieboldianae C. Nakash., Crous, U. Braun & H.D. Shin, Cercospora pileicola C. Nakash., Crous, U. Braun & H.D. Shin, Cercospora vignigena C. Nakash., Crous, U. Braun & H.D. Shin. Typifications: epitypifications - Cercospora alchemillicola U. Braun & C.F. Hill, Cercospora althaeina Sacc., Cercospora armoraciae Sacc., Cercospora corchori Sawada, Cercospora mercurialis Pass., Cercospora olivascens Sacc., Cercospora violae Sacc.; neotypifications - Cercospora fagopyri N. Nakata & S. Takim., Cercospora sojina Hara.

No MeSH data available.


Related in: MedlinePlus

Foliar disease symptoms associated with Cercospora spp. A. C. achyranthis on Achyranthes japonica. B. C. dispori on Disporum viridescens. C. C. chinensis on Polygonatum humile. D. C. cf. flagellaris on Amaranthus patulus. E. C. capsici on Capsicum annuum. F. Cercospora sp. on Ajuga multiflora. G. Cercospora sp. on Cardamine leucanthe. H. C. cf. flagellaris on Celosia argentea var. cristata. I. C. zeina on Zea mays. J. C. beticola on Beta vulgaris. K. C. chrysanthemi on Chrysanthemum. L. C. apii on Apium. M. C. amoraciae on Rorippa indica. N. C. beticola on Chrysanthemum segetum. O. C. apiicola on Apium. P. C. ipomoeae on Persicaria thunbergii. Q. C. althaeina on Althaea rosea. R. C. zebrina on Trifolium repens. S. C. sojina on Glycine max. T. C. brunkii on Geranium nepalense.
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Figure 1: Foliar disease symptoms associated with Cercospora spp. A. C. achyranthis on Achyranthes japonica. B. C. dispori on Disporum viridescens. C. C. chinensis on Polygonatum humile. D. C. cf. flagellaris on Amaranthus patulus. E. C. capsici on Capsicum annuum. F. Cercospora sp. on Ajuga multiflora. G. Cercospora sp. on Cardamine leucanthe. H. C. cf. flagellaris on Celosia argentea var. cristata. I. C. zeina on Zea mays. J. C. beticola on Beta vulgaris. K. C. chrysanthemi on Chrysanthemum. L. C. apii on Apium. M. C. amoraciae on Rorippa indica. N. C. beticola on Chrysanthemum segetum. O. C. apiicola on Apium. P. C. ipomoeae on Persicaria thunbergii. Q. C. althaeina on Althaea rosea. R. C. zebrina on Trifolium repens. S. C. sojina on Glycine max. T. C. brunkii on Geranium nepalense.

Mentions: Species of Cercospora are commonly associated with leaf spots (Fig. 1), and have also been isolated from necrotic lesions of flowers, fruits and seeds or were associated with postharvest fruit rot disease (Silva & Pereira 2008) of hosts from across the world (Agrios 2005, To-Anun et al. 2011). The cercosporoid fungi have also been used as biocontrol agents (Morris & Crous 1994, Inglis et al. 2001, Tessman et al. 2001). Species of Cercospora were traditionally named after the host from which they were isolated, even to the extent that a species of Cercospora was described as new when found on a different host plant (Chupp 1954, Ellis 1971). The genus Cercospora was first erected by Fresenius for passalora-like fungi with pluriseptate conidia (in Fuckel 1863). Chupp’s (1954) monograph accepted 1 419 Cercospora species and proposed a broad concept for this genus based on whether hila were thickened or not, and whether conidia were pigmented, single or in chains. The number of Cercospora species doubled to more than 3 000 when Pollack (1987) published her annotated list of Cercospora names. Since then a combination of characters such as conidiomatal structure, mycelium, conidiophores, conidiogenous cells and conidia has been used to divide the genus into morphologically similar units. Crous & Braun (2003) used the structure of conidiogenous loci and hila as well as the absence or presence of pigmentation in conidiophores and conidia in their revision of names published in Cercospora and Passalora. They recognised 659 names in the genus Cercospora, with a further 281 names referred to as C. apii s. lat. The C. apii complex represented Cercospora species that were morphologically indistinguishable from C. apii (Ellis 1971, Crous & Braun 2003). In addition, Crous & Braun (2003) introduced the concept of “compound species” which consisted of morphologically indistinguishable species with different races (host range), genetically uniform or heterogeneous, with different degrees of biological specialisation. They also proposed that genetically and morphologically clearly distinguishable taxa should be treated as separate species, although the study was confounded by the general unavailability of Cercospora cultures for DNA analyses. Ex-type strains mostly do not exist as such isolates were neither designated nor preserved, for the majority of Cercospora species (Groenewald et al. 2010a). For most Cercospora species, a sexual stage (a mycosphaerella-like state) is not known; or has been reported, but not confirmed (Goodwin et al. 2001). The mating type genes of some apparently asexual Cercospora species were recently characterised, with the discovery that C. beticola, C. zeae-maydis and C. zeina were heterothallic, although only one mating type was present in populations of C. apii and C. apiicola (Groenewald et al. 2006b, 2010b). The two mating types of C. beticola were distributed approximately equally in the tested populations, indicating that these genes might indeed be active, indicative of cryptic sex. More recently a skewed distribution of mating types across sugar beet fields from different localities was report from Iran, with some fields having both mating types and others only the one or the other (Bakhshi et al. 2011). A further study conducted over a 3-yr period in the USA, also led to the conclusion that C. beticola has potential for sexual reproduction (Bolton et al. 2012).


Species concepts in Cercospora: spotting the weeds among the roses.

Groenewald JZ, Nakashima C, Nishikawa J, Shin HD, Park JH, Jama AN, Groenewald M, Braun U, Crous PW - Stud. Mycol. (2013)

Foliar disease symptoms associated with Cercospora spp. A. C. achyranthis on Achyranthes japonica. B. C. dispori on Disporum viridescens. C. C. chinensis on Polygonatum humile. D. C. cf. flagellaris on Amaranthus patulus. E. C. capsici on Capsicum annuum. F. Cercospora sp. on Ajuga multiflora. G. Cercospora sp. on Cardamine leucanthe. H. C. cf. flagellaris on Celosia argentea var. cristata. I. C. zeina on Zea mays. J. C. beticola on Beta vulgaris. K. C. chrysanthemi on Chrysanthemum. L. C. apii on Apium. M. C. amoraciae on Rorippa indica. N. C. beticola on Chrysanthemum segetum. O. C. apiicola on Apium. P. C. ipomoeae on Persicaria thunbergii. Q. C. althaeina on Althaea rosea. R. C. zebrina on Trifolium repens. S. C. sojina on Glycine max. T. C. brunkii on Geranium nepalense.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3713887&req=5

Figure 1: Foliar disease symptoms associated with Cercospora spp. A. C. achyranthis on Achyranthes japonica. B. C. dispori on Disporum viridescens. C. C. chinensis on Polygonatum humile. D. C. cf. flagellaris on Amaranthus patulus. E. C. capsici on Capsicum annuum. F. Cercospora sp. on Ajuga multiflora. G. Cercospora sp. on Cardamine leucanthe. H. C. cf. flagellaris on Celosia argentea var. cristata. I. C. zeina on Zea mays. J. C. beticola on Beta vulgaris. K. C. chrysanthemi on Chrysanthemum. L. C. apii on Apium. M. C. amoraciae on Rorippa indica. N. C. beticola on Chrysanthemum segetum. O. C. apiicola on Apium. P. C. ipomoeae on Persicaria thunbergii. Q. C. althaeina on Althaea rosea. R. C. zebrina on Trifolium repens. S. C. sojina on Glycine max. T. C. brunkii on Geranium nepalense.
Mentions: Species of Cercospora are commonly associated with leaf spots (Fig. 1), and have also been isolated from necrotic lesions of flowers, fruits and seeds or were associated with postharvest fruit rot disease (Silva & Pereira 2008) of hosts from across the world (Agrios 2005, To-Anun et al. 2011). The cercosporoid fungi have also been used as biocontrol agents (Morris & Crous 1994, Inglis et al. 2001, Tessman et al. 2001). Species of Cercospora were traditionally named after the host from which they were isolated, even to the extent that a species of Cercospora was described as new when found on a different host plant (Chupp 1954, Ellis 1971). The genus Cercospora was first erected by Fresenius for passalora-like fungi with pluriseptate conidia (in Fuckel 1863). Chupp’s (1954) monograph accepted 1 419 Cercospora species and proposed a broad concept for this genus based on whether hila were thickened or not, and whether conidia were pigmented, single or in chains. The number of Cercospora species doubled to more than 3 000 when Pollack (1987) published her annotated list of Cercospora names. Since then a combination of characters such as conidiomatal structure, mycelium, conidiophores, conidiogenous cells and conidia has been used to divide the genus into morphologically similar units. Crous & Braun (2003) used the structure of conidiogenous loci and hila as well as the absence or presence of pigmentation in conidiophores and conidia in their revision of names published in Cercospora and Passalora. They recognised 659 names in the genus Cercospora, with a further 281 names referred to as C. apii s. lat. The C. apii complex represented Cercospora species that were morphologically indistinguishable from C. apii (Ellis 1971, Crous & Braun 2003). In addition, Crous & Braun (2003) introduced the concept of “compound species” which consisted of morphologically indistinguishable species with different races (host range), genetically uniform or heterogeneous, with different degrees of biological specialisation. They also proposed that genetically and morphologically clearly distinguishable taxa should be treated as separate species, although the study was confounded by the general unavailability of Cercospora cultures for DNA analyses. Ex-type strains mostly do not exist as such isolates were neither designated nor preserved, for the majority of Cercospora species (Groenewald et al. 2010a). For most Cercospora species, a sexual stage (a mycosphaerella-like state) is not known; or has been reported, but not confirmed (Goodwin et al. 2001). The mating type genes of some apparently asexual Cercospora species were recently characterised, with the discovery that C. beticola, C. zeae-maydis and C. zeina were heterothallic, although only one mating type was present in populations of C. apii and C. apiicola (Groenewald et al. 2006b, 2010b). The two mating types of C. beticola were distributed approximately equally in the tested populations, indicating that these genes might indeed be active, indicative of cryptic sex. More recently a skewed distribution of mating types across sugar beet fields from different localities was report from Iran, with some fields having both mating types and others only the one or the other (Bakhshi et al. 2011). A further study conducted over a 3-yr period in the USA, also led to the conclusion that C. beticola has potential for sexual reproduction (Bolton et al. 2012).

Bottom Line: Some species were found to be limited to a specific host genus, whereas others were isolated from a wide host range.No single locus was found to be the ideal DNA barcode gene for the genus, and species identification needs to be based on a combination of gene loci and morphological characters.Takim., Cercospora sojina Hara.

View Article: PubMed Central - PubMed

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

ABSTRACT

Unlabelled: The genus Cercospora contains numerous important plant pathogenic fungi from a diverse range of hosts. Most species of Cercospora are known only from their morphological characters in vivo. Although the genus contains more than 5 000 names, very few cultures and associated DNA sequence data are available. In this study, 360 Cercospora isolates, obtained from 161 host species, 49 host families and 39 countries, were used to compile a molecular phylogeny. Partial sequences were derived from the internal transcribed spacer regions and intervening 5.8S nrRNA, actin, calmodulin, histone H3 and translation elongation factor 1-alpha genes. The resulting phylogenetic clades were evaluated for application of existing species names and five novel species are introduced. Eleven species are epi-, lecto- or neotypified in this study. Although existing species names were available for several clades, it was not always possible to apply North American or European names to African or Asian strains and vice versa. Some species were found to be limited to a specific host genus, whereas others were isolated from a wide host range. No single locus was found to be the ideal DNA barcode gene for the genus, and species identification needs to be based on a combination of gene loci and morphological characters. Additional primers were developed to supplement those previously published for amplification of the loci used in this study.

Taxonomic novelties: New species - Cercospora coniogrammes Crous & R.G. Shivas, Cercospora delaireae C. Nakash., Crous, U. Braun & H.D. Shin, Cercospora euphorbiae-sieboldianae C. Nakash., Crous, U. Braun & H.D. Shin, Cercospora pileicola C. Nakash., Crous, U. Braun & H.D. Shin, Cercospora vignigena C. Nakash., Crous, U. Braun & H.D. Shin. Typifications: epitypifications - Cercospora alchemillicola U. Braun & C.F. Hill, Cercospora althaeina Sacc., Cercospora armoraciae Sacc., Cercospora corchori Sawada, Cercospora mercurialis Pass., Cercospora olivascens Sacc., Cercospora violae Sacc.; neotypifications - Cercospora fagopyri N. Nakata & S. Takim., Cercospora sojina Hara.

No MeSH data available.


Related in: MedlinePlus