Morphological and Molecular Characterization of spp. Isolated from European Pears.

In a recent survey of post-harvest rot pathogens in European pear in Southern Oregon, spp. were frequently isolated from orchard samples of pear flowers and fruits. Morphological differences were observed within the isolated cultures. A preliminary NCBI BLAST search analysis using sequences of the ATPase locus across 94 isolates of spp. obtained from pear fruit rots revealed three major sections: sect. , sect. , and sect. . Thirteen isolates were selected based on their genetic and morphological diversity across three sections and were subjected to multilocus phylogenetic analysis using sequences from plasma membrane ATPase, calmodulin, and loci. Within sect. , four isolates and one . isolate were identified; within sections and , one . isolate and two . isolates were identified, respectively. The remaining five isolates could not be identified based on the available sequences for the three loci used in this study. In addition to the phylogenetic analysis, pathogenicity assays revealed differential responses to these isolates on four pear cultivars: Anjou, Bartlett, Comice, and Bosc. Inoculation of isolates within sect. resulted in fruit lesions across all cultivars, with Bosc pear being significantly susceptible ( 0.0001). Isolates within sect. caused rots on Anjou and Bosc pears, while isolates within sect. developed rots on Bosc pear only. This study suggests that there is differential susceptibility of pear cultivars to Alternaria rots, and the severity of post-harvest rot depends on the type of spp. and cultivar predominant in a region.