Rhizoctonia solani AG 1-IB and AG 4 HG-I causing leaf blight and root rot in plants from the Lamiaceae family in Brazil

摘要

Rhizoctonia solani is a fungal complex represented by 14 anastomosis groups. Each group has distinct characteristics that are reflected in the management and control strategies for diseases caused by this fungus. In three distinct geographical regions, plants of the Lamiaceae family from vegetable and medicinal herb gardens were observed, with Mentha piperina, Mentha spicata and Origanum manjerona presenting symptoms of leaf blight and Ocimum basilicum, Ocimum vulgare and Rosmarinus officinalis presenting root rot symptoms. Mycelia, hymenia, basidiospores and microsclerotia were found on the stems and leaves of Mentha piperina and Mentha spicata. These are typical morphological markers of the genus Rhizoctonia. The ITS region was amplified for nineisolates and subsequently sequenced. In the phylogenetic analysis, the isolates were identified as Rhizoctonia solani belonging to AG 1-IB and AG 4 HG-I anastomosis groups. All isolates inoculated in their respective hosts caused disease symptoms resembling those typically observed in the field. This is the first report of R. solani AG 1-IB in M. spicata, M. piperina and Origanum majorana and of R. solani AG 4 HG-I in O. vulgare, R. officinalis and O. basilicum in Brazil.