Colletotrichum gloeosporioides sensu stricto: an endophytic species or citrus pathogen in Brazil?

Postbloom fruit drop (PFD) was first associated with Colletotrichum gloeosporioides until 1990s. Thereafter, the causal agent was reclassified as a species belonging to C. acutatum complex. Recent findings suggested that among the species, within the C. acutatum complex, C. abscissum is the PFD causal agent. Moreover, previous study reported C. abscissum as the most frequent species among isolates of Colletotrichum from blooms showing PFD symptoms. Despite the recent increase in knowledge concern PFD epidemiology, strategies of pathogen survival in citrus leaves remain unclear. Therefore, the aim of this study was to identify the Colletotrichum endophytic species obtained from leaves of sweet orange and weeds from orchards located in Sao Paulo state, Brazil, and to evaluate the ability of these isolates to cause typical PFC symptoms on flowers. Species-specific PCR was used to identify 188 isolates belonging to the C. gloeosporioides complex, which were characterized as C. gloeosporioides sensu stricto based on multilocus sequence analysis. The pathogenicity test indicated that one isolate of C. gloeosporioides sensu stricto, obtained from citrus leaf, was associated with PFD symptoms on inoculated flowers. Lastly, the species associated with PFD may survive on leaf surface, but only C. gloeosporioides sensu stricto is able to colonize endophytically the sweet orange leaves in Brazil.