Utility of internally transcribed spacer region of rDNA (ITS) and β‐tubulin gene sequences to infer genetic diversity and migration patterns of Colletotrichum truncatum infecting Capsicum spp.

Anthracnose is among the most economically important diseases affecting pepper (Capsicum spp.) production in the tropics and subtropics. Of the three species of Colletotrichum implicated as causal agents of pepper anthracnose, C. truncatum is considered to be the most destructive in agro-ecosystems worldwide. However, the genetic variation and the migration potential of C. truncatum infecting pepper are not known. Five populations were selected for study and a two-locus (internally transcribed spacer region, ITS1-5.8S-ITS2, and β-tubulin, β-TUB) sequence data set was generated and used in the analyses. Sequences of the ITS region were less informative than β -tubulin gene sequences based on comparisons of DNA polymorphism indices. Trinidad had the highest genetic diversity and also had the largest effective population size in pairwise comparisons with the other populations. The Trinidad population also demonstrated significant genetic differentiation from the other populations. AMOVA and STRUCTURE analyses both suggested significant genetic variation within populations more so than among populations. A consensus Maximum Likelihood tree based on β-TUB gene sequences revealed very little intraspecific diversity for all isolates except for Trinidad. Two clades consisting solely of Trinidad isolates may have diverged earlier than the other isolates. There was also evidence of directional migration among the five populations. These findings may have a direct impact on the development of integrated disease management strategies to control C. truncatum infection in pepper.