@ARTICLE{TreeBASE2Ref22267, author = {Mireia Puig and Lídia Ruz and Emilio Montesinos and Concepció Moragrega and Isidre Llorente}, title = {Combined morphological and molecular approach for identification of Stemphylium vesicarium inoculum in pear orchards }, year = {2014}, keywords = {Brown spot of pear; gpd partial sequence; internal transcriber spacer; pathogenicity; sequencing; phylogeny}, doi = {10.1016/j.funbio.2014.11.006}, url = {http://www.sciencedirect.com/science/article/pii/S1878614614001779}, pmid = {}, journal = {Fungal Biology}, volume = {}, number = {}, pages = {}, abstract = {Stemphylium vesicarium is the causal agent of brown spot of pear (BSP), an important disease reported in pear-growing areas of Europe. The pathogen is able to colonize pear leaf debris and dead tissues of herbaceous plants on the ground and produce abundant ascospores and conidia that are capable of infecting pear trees. Inoculum monitoring in pear orchards is mainly achieved through spore traps and species identification is based on conidial morphology, but the similarities on conidial traits among species of Stemphylium make correct identification difficult. In this work a total of thirty-seven Stemphylium isolates recovered from different sources in pear orchards were characterized at the morphological, pathogenic and molecular level. Correspondence among ITS and gpd sequences and morphological traits were evaluated in order to determine their applicability in identification of S. vesicarium. Species identification based exclusively on morphological data was not feasible. Three different morphological groups were resolved according to colony and conidial morphology, but conidial dimensions of these groups were in the range described for S. vesicarium. Molecular analyses of the ITS and gpd sequences clustered field isolates in the S. vesicarium - S. herbarum-S. alfalfae- S. tomatonis and S. sedicola (84%), S. eturmiunum (13.5%), and S. gracilariae (2.5%) species groups. Combined morphological and molecular data were necessary for unambiguous identification of isolates in the S. vesicarium species group. Only isolates identified as S. vesicarium were pathogenic on pear. In this taxonomic group, differences in pathogenicity were observed, mainly related to their origin. Most isolates recovered from lesions (87%)were pathogenic, whereas 60% of isolates recovered from air samples or from nonhost plant species were nonpathogenic on pear. The study revealed that several species of Stemphylium coexist in pear orchards with S. vesicarium, the causal agent of BSP, and that combined morphological and molecular data are needed to differentiate them. Consequently, direct measurements of the airborne inoculum using volumetric spore traps and conidia may overestimate the actual pathogen population and its pathogenic potential.} }

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