Genomic analyses of five Fusarium species infecting cannabis (Cannabis sativa L.) plants in Canada and their potential for mycotoxin production

Fusarium species are important pathogens that affect many vegetable, cereal, and pulse crops in Canada. These pathogens also infect a diverse range of horticultural crops, including cannabis (Cannabis sativa L.). A range of disease symptoms have been reported on cannabis plants upon infection by several Fusarium species, which include root rot, wilting, stem rot, and bud rot. In this study, we report the genome sequences of five Fusarium species that were recovered from symptomatic greenhouse-grown cannabis plants in British Columbia: F. graminearum, F. sporotrichioides, F. culmorum, F. proliferatum, and F. oxysporum. Comparative genomic analysis revealed that the isolates from cannabis displayed a high percentage genome alignment to currently recognized pathogenic Fusarium species infecting other crops. This may suggest that horizontal transmission of the pathogens has occurred between these crops, potentially through air, soil, or seed-borne inoculum. In addition, analysis of secondary metabolites and toxin production in the Fusarium species affecting cannabis indicated they have the potential to produce several mycotoxins, including trichothecenes, fumonisin, zearalenone, beauvericin and culmorin. Further epidemiological and in planta studies are needed to establish the extent to which horizontal spread of Fusarium species from horticultural and field crops to cannabis plants is occurring and the impact this can have on post-harvest quality and mycotoxin production. Studies on genetic changes that may be occurring in the Fusarium species as they adapt to cannabis as a host would provide evolutionary insights into the pathogenicity of this complex, versatile and important group of plant pathogens.