Identification and genetic diversity of Rosellinia spp. associated with root rot of coffee in Colombia

The genus Rosellinia includes species that cause root rot on a wide range of herbaceous and woody hosts. In Colombia, these fungi cause serious diseases of potato, forest and fruit trees, as well as coffee plants. The aim of this study was to identify isolates of Rosellinia collected from coffee and other hosts using DNA sequence comparisons of the internal transcribed spacer (ITS) region. Pathogenicity tests were conducted on coffee seedlings to confirm the role of the collected species in coffee root disease. Twenty six isolates were obtained and these were grouped into two clades representing R. bunodes and R. pepo. Isolates from Coffea arabica, Hevea brasiliensis, Macadamia integrifolia, Psidium guajava and Theobroma cacao were identified as R. pepo, while R. bunodes was obtained only from coffee plants. Low levels of genetic variability were observed among isolates of the two species. Pathogenicity tests on coffee with R. bunodes resulted in 98 % seedling death in an average of 10 days, while R. pepo killed 54 % of inoculated seedlings in an average of 16 days confirming the compatibility of both species with this host. Pathogen characterization will be useful for further research in disease diagnosis, soil recovery and breeding for resistance.