Characterization of Colletotrichum Species as Causal Agents of Anthracnose in Strawberry Productive Areas in Tucumán, Argentina

Abstract

Objective: Anthracnose is a disease caused by Colletotrichum species and is a significant disease in the strawberry crop. This study aims to identify at the level of species Colletotrichum spp. isolates collected from symptomatic strawberry plants in Tucumán, Argentina’s second most important strawberry production area.Methods: 45 isolates of Colletotrichum were collected and characterized. Morphological characterization was conducted by analyzing fungal cultural characteristics, the growth rate in potato dextrose agar plates, conidial morphology and size, and sexual state. Phytopathological characterization was carried out by plant-pathogen interactions under controlled conditions in infection chambers. Molecular characterization was performed by polymerase chain reaction analysis of regions of amplified mitochondrial small rRNA genes. Results: Preliminary morphological characterization led to three distinctive groups, based on conidial shape and size, and colony type, colour, and growth, whereas the phytopathological characterization, led to two distinct groups based on the severity of symptoms, virulence, and host specificity. Molecular analyses confirmed the identity of three isolates representing each of the microbiological groups (i.e., isolate F7 of Colletotrichum acutatum (C. acutatum), isolate L9 of C. acutatum, isolate M11 of C. acutatum), demonstrating that they correspond to C. acutatum species. Based on the analysis of ribosomal DNA internal transcribed spacers sequences, and using specific microsatellites, we found a high genetic variability among all C. acutatum sequences. Implications of these results, as well as biological products commercially available and research advancing the field of biological control agents, were also discussed. Conclusion: This is the latest study to report with confidence that the species of Colletotrichum present in Tucumán, Argentina corresponds to C. acutatum, and such species are genetically diverse.