High Species Diversity in Associated with Citrus Diseases in Europe

Species of are considered important plant pathogens, saprobes, and endophytes on a wide range of plant hosts. Several species are well-known on citrus, either as agents of pre- or post-harvest infections, such as anthracnose, postbloom fruit drop, tear stain and stem-end rot on fruit, or as wither-tip of twigs. In this study we explored the occurrence, diversity and pathogenicity of spp. associated with and allied genera in European orchards, nurseries and gardens. Surveys were carried out during 2015 and 2016 in Greece, Italy, Malta, Portugal and Spain. A total of 174 strains were isolated from symptomatic leaves, fruits, petals and twigs. A multi-locus phylogeny was established based on seven genomic loci (ITS, , , , , and ), and the morphological characters of the isolates determined. Preliminary pathogenicity tests were performed on orange fruits with representative isolates. strains were identified as members of three major species complexes. s.str. and two novel species ( and ) were identified in the species complex. , and two novel species ( and ) in the species complex, and s.str. was also isolated as member of species complex. and were the predominant species of isolated. This study represents the first report of on citrus in Europe, and the first detection of from outside New Zealand. Pathogenicity tests revealed s.str. to be the most virulent species on fruits. The present study improves our understanding of species associated with several disease symptoms on citrus fruits and plants, and provides useful information for effective disease management.