Colletotrichum spp. causing anthracnose in Codiaeum variegatum in Southern Brazil

Codiaeum variegatum is an ornamental plant widely cultivated in various regions of the world, valued for the coloration and diversity of its leaves. In July 2022, reddish-brown lesions were observed on the leaves of plants cultivated in a residence in the state of Rio Grande do Sul, Brazil. In view of this, the aim of this study was to isolate, characterize, and identify the causal agent of anthracnose in C. variegatum through morphological and molecular traits. Pure cultures were obtained from the lesions in potato dextrose agar (PDA). To fulfill Koch’s postulates, disks of agar containing fungal structures were placed on healthy C. variegatum leaves. After the incubation period under controlled conditions, red spots were observed on the inoculated areas, similar to the original lesions. The isolates were morphologically characterized and molecularly identified using the ITS (Internal Transcribed Spacer), Calmodulin (CAL), and Glyceraldehyde-3-phosphate Dehydrogenase (GAPDH) gene regions. The morphological and sequence analysis confirmed the species Colletotrichum karstii and Colletotrichum gigasporium as the causal pathogens of anthracnose in C. variegatum. The sequences of the ITS, CAL, and GAPDH genes from the isolates were deposited in GenBank, and a culture of each pathogen was deposited in the Herbarium of the Department of Biology at the Universidade Federal de Santa Maria. The pathogens were registered in the National System for the Management of Genetic Heritage and Associated Traditional Knowledge. This is the first report of C. karstii and C. gigasporium causing anthracnose in C. variegatum in Brazil.