Crown gall development on cannabis (<i>Cannabis sativa</i> L., marijuana) plants caused by <i>Agrobacterium tumefaciens</i> species-complex

Crown gall, caused by Agrobacterium tumefaciens (syn. Rhizobium radiobacter), is characterized gall formation on crowns, stems or roots many plant species. We describe the occurrence of this disease for first time cannabis (Cannabis sativa L. marijuana) plants in two licenced production facilities British Columbia. Galls were observed and several genotypes, including ‘White Rhino’, ‘Pink Kush’ ‘Sour Kush’. The affected displayed no other visible symptoms. incidence crown was extremely low, estimated at 0.01% total plants. Isolations made from root stem galls MacConkey medium (selective Gram -ve bacteria) D1 spp.) yielded a range bacterial species, which did not include sp. However, presence tissues confirmed following PCR amplification with primers indole-acetic acid (iaa) H gene T-DNA region spp. showed > 99% similarity to A. tumefaciens. Artificial inoculations conducted using an strain ATCC (Rhizobium radiobacter, designation TT134 [6-1-2, CIP 104 336], cat. 15955) resulted five genotypes tested. These contained iaaH as determined pathogen successfully re-isolated agar 4 10 weeks post-inoculation. Our findings confirm naturally infected artificially grown under greenhouse conditions demonstrate reproducible symptoms inoculation.