Genetically differentiated populations of Ceratocystis fimbriata species complex points to host specialization in Brazil

Ceratocystis fimbriata is an important pathogen with a wide host range that causes xylem lesions, wilt and death in different plant species. More adapted populations of C. fimbriata have probably been selected to specific hosts and high genetic and physiological variability can be found within the pathogen populations. Thus, molecular analysis and inoculation studies were performed to investigate the genetic and physiological variability of isolates of C. fimbriata complex obtained from different host species and geographic regions in Brazil. The minimum spanning tree analysis based on 14 simple‐sequence repeat (SSR) markers of C. fimbriata exhibited a clear clustering of isolates according to host, where each groups of isolates differed in at least five loci. In addition, inoculation of eight hosts with 10 isolates revealed a wide variation in aggressiveness. By assessing the length of xylem lesions caused by C. fimbriata isolates, Ficus carica was found to be the most susceptible host, followed by Mangifera indica. Only the isolates from Theobroma cacao and Carapa guianensis proved to be host specialized. Overall, the isolates tested were more aggressive to the hosts from which they were sampled. There is significant genetic and physiological variability within the populations of Ceratocystis fimbriata. It is possible that some populations have adapted to particular host species.