Identifier: TDX:3396
Authors: Iturrieta González, Isabel
Abstract:
The present thesis was focused on the study of species diversity and taxonomy of the genera Alternaria and Cladosporium, but also of other dematiaceous hyphomycetes belonging to morphologically similar genera. A total of 589 isolates were studied; 56 from clinical origin and 533 from environmental samples (204 from herbivore dung, 200 from soil, 129 from plant debris) collected in Spain, but also in Mexico, and Vietnam. The genera aimed of our research are considered taxonomically complex, due to the difficulties in the classification of their species using only morphological traits. The real spectrum of species diversity associated to a particular substrate is only known if molecular studies based on sequence analyses of appropriate phylogenetic markers are used for species recognition. Phenotypic characterization of the isolates and sequence analyses of ITS and LSU barcodes of the ribosomal DNA, as well as of the partial regions of protein encoding genes as actin, ATPase, glyceraldehyde-3-phosphate dehydrogenase, elongation factor, RNA polymerase II and β-tubulin, depending on the genus studied, allowed us to identify: 39 Alternaria species, including 13 new described for science and 11 undescribed phylogenetic species, still under characterization; 45 Cladosporium species, including seven new species and one undescribed species still under study; 10 Curvularia species, three proposed as new; the new genus Neodendryphiella with three novel species; two new species in the genus Pseudopenidiella and five more novel fungi classified in Apenidiella, Cyphellophora, Heliocephala, Matsushimaea, and Venturia. Of note is that among the new Alternaria, three proved to be agents of human cutaneous alternariosis (A. anthropophila, A. atrobrunnea and A. guarroi). We observed a high species diversity in both Alternaria and Cladosporium isolates from environmental sources, but herbivore dung was the substrate where more novel or rare taxa were recovered, concluding that it is an excellent reservoir of interesting hyphomycetes.
Repositori URV