RESUMEN
Coniothyrium zuluense causes a serious canker disease of Eucalyptus in various parts of the world. Very little is known regarding the taxonomy of this asexual fungus, which was provided with a name based solely on morphological characteristics. In this study we consider the phylogenetic position of C. zuluense using DNA-based techniques. Distance analysis using 18S and ITS regions revealed extensive sequence divergence relative to the type species of Coniothyrium, C. palmarum and species of Paraconiothyrium. Coniothyrium zuluense was shown to be an anamorph species of Mycosphaerella, a genus that includes a wide range of Eucalyptus leaf and stem pathogens. Within Mycosphaerella it clustered with taxa having pigmented, verruculose, aseptate conidia that proliferate percurrently and sympodially from pigmented conidiogenous cells arranged in conidiomata that vary from being pycnidial to acervular. The genus Colletogloeopsis is emended to include species with pycnidial conidiomata, and the new combination Colletogloeopsis zuluense is proposed. This is also the first report of the pathogen from China where it is associated with stem cankers on Eucalyptus urophylla.
Asunto(s)
Ascomicetos/crecimiento & desarrollo , Eucalyptus , Enfermedades de las Plantas/microbiología , Ascomicetos/clasificación , Ascomicetos/genética , Secuencia de Bases , China , ADN de Hongos/química , ADN de Hongos/genética , ADN Espaciador Ribosómico/química , ADN Espaciador Ribosómico/genética , Filogenia , Reacción en Cadena de la Polimerasa , ARN Ribosómico 18S/química , ARN Ribosómico 18S/genética , ARN Ribosómico 5.8S/química , ARN Ribosómico 5.8S/genética , Alineación de Secuencia , Análisis de Secuencia de ADNRESUMEN
A PCR-based technique based on the ITS1-5.8s-ITS2 domain of the rRNA gene for identifying five species associated with Mycosphaerella leaf disease (MLD) of eucalypts was developed. Primer pairs MC2F and MC2R; ML1F and ML1R; MM1F and MM1R; MN1F and MN1R; and MP1F and MP1R amplified a product for DNA extracted from their single target species, those being M. cryptica, M. lateralis, M. marksii, M. nubilosa and M. parva, respectively. The possibility of false positive amplification by each primer pair was tested in reactions with DNA extracts from 16 other Mycosphaerella species associated with eucalypts and against non-infected Eucalyptus globulus leaves. Under the PCR conditions used, there were no false positive amplifications of the 16 non-target Mycosphaerella species, or from non-symptomatic E. globulus leaves for the primer pairs ML1F and ML1R; MM1F and MM1R; MN1F and MN1R; and MP1F and MP1R. The primer pair MC2F and MC2R amplified a 402 nt product from both the target M. crvptica and non-target M. nubilosa. However, these two species were differentiated by digesting the product with the restriction enzyme Sacc II which resulted in a single 402 nt product for M. cryptica, and two products of 78 and 324 nt for M. nubilosa. All of the primers were able to detect their target Mycosphaerella species from Eucalyptus globulus lesions. PCR reactions with these primers on DNA extracted from Mycosphaerella lesions confirmed the presence of all five species from leaf material collected from three plantations in Western Australia.
Asunto(s)
Ascomicetos/aislamiento & purificación , Eucalyptus/microbiología , Enfermedades de las Plantas/microbiología , Reacción en Cadena de la Polimerasa/métodos , Ascomicetos/clasificación , Ascomicetos/genética , Cartilla de ADN , ADN Espaciador Ribosómico , Genes de ARNr/genética , Datos de Secuencia Molecular , Filogenia , Hojas de la Planta/microbiología , Sensibilidad y Especificidad , Especificidad de la EspecieRESUMEN
Mycosphaerella ambiphylla sp. nov. (anamorph: Phaeophleospora) and Mycosphaerella aurantia sp. nov., are described from diseased Eucalyptus globulus leaves. In addition, a new fungal record in Australia, M. mexicana, and two new records for Western Australia, M. gregaria and M. parva, are discussed. A key is provided to Mycosphaerella species on E. globulus in Western Australia.