Characterization of Colletotrichum truncatum from papaya, pepper and physic nut based on phylogeny, morphology and pathogenicity

Colletotrichum truncatum (syn. C.capsici) has been identified as the causal agent of anthracnose on various hosts, predominantly pepper (Capsicum spp.) plants. The aim of this study was to determine whether C.truncatum isolates infecting papaya, pepper and physic nut in southeastern Mexico are morphologically, genetically and pathogenically different, in order to improve disease management strategies. A total of 113 C.truncatum isolates collected from five producer states were subjected to phenotypic characterization and divided into six different morphological groups. These morphological traits and the location of the isolates were used to select a subset of 20 isolates for further studies. Differences in the pathogenicity of the isolates were tested with a cross-inoculation assay using pepper, papaya and physic nut. The pathogenicity tests revealed that all isolates could infect the three hosts and produce typical anthracnose symptoms, indicating a lack of host specificity for this species and therefore its pathogenic potential on other plants. Phylogenetic analysis using internal transcribed spacer (ITS) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) sequences of the C.truncatum isolates from this study and reference strains was performed, grouping the isolates into a monophyletic clade. This study reports for the first time the characterization of C.truncatum causing anthracnose disease on three different hosts in Mexico.