Molecular diversity of anthracnose pathogen populations associated with UK strawberry production suggests multiple introductions of three different Colletotrichum species.

Fragaria × ananassa (common name: strawberry) is a globally cultivated hybrid species belonging to Rosaceae family. Colletotrichum acutatum sensu lato (s.l.) is considered to be the second most economically important pathogen worldwide affecting strawberries. A collection of 148 Colletotrichum spp. isolates including 67 C. acutatum s.l. isolates associated with the phytosanitary history of UK strawberry production were used to characterize multi-locus genetic variation of this pathogen in the UK, relative to additional reference isolates that represent a worldwide sampling of the diversity of the fungus. The evidence indicates that three different species C. nymphaeae, C. godetiae and C. fioriniae are associated with strawberry production in the UK, which correspond to previously designated genetic groups A2, A4 and A3, respectively. Among these species, 12 distinct haplotypes were identified suggesting multiple introductions into the country. A subset of isolates was also used to compare aggressiveness in causing disease on strawberry plants and fruits. Isolates belonging to C. nymphaeae, C. godetiae and C. fioriniae representative of the UK anthracnose pathogen populations showed variation in their aggressiveness. Among the three species, C. nymphaeae and C. fioriniae appeared to be more aggressive compared to C. godetiae. This study highlights the genetic and pathogenic heterogeneity of the C. acutatum s.l. populations introduced into the UK linked to strawberry production

Virulence diversity of anthracnose pathogens (Colletotrichum acutatum and C. gloeosporioides complexes) on eight olive cultivars commonly grown in Portugal.

Olive anthracnose, caused by Colletotrichum acutatum and C. gloeosporioides species complexes, is a major disease affecting fruits at maturity, causing significant yield losses, and poor fruit and oil quality. Diverse genetic groups, particularly belonging to C. acutatum s.l. have been reported among the pathogens, with recent research proposing these genetic groups as distinct species. In this work, the virulence diversity of isolates representing different populations of C. acutatum s.l. and C. gloeosporioides s.s. was studied using a set of eight olive cultivars. Higher disease severity was produced by isolates belonging to groups A2 and A5 of C. acutatum s.l. (=C. nymphaeae and C. acutatum s.s., respectively) compared to C. gloeosporioides s.s. isolates as well as isolates of C. acutatum s.l. group A4 (=C. godetiae). Anthracnose severity was higher on the cultivars ‘Cobrançosa’, ‘Maçanilha de Tavira’ and ‘Galega Vulgar’ and lower in ‘Azeitoneira’, ‘Blanqueta’, ‘Negrinha de Freixo’ and ‘Picual’, but results indicate the occurrence of isolate × cultivar interactions. Differences in severity could be related to differences in conidia germination and appressoria formation, suggesting that early host-pathogen recognition events can in part explain disease severity under favourable environmental conditions. Overall results revealed the higher virulence and fitness levels of genotypes belonging to certain genetic groups within C. acutatum suggesting their ability to adapt to diverse agro-climatic conditions including specific hosts