Genetic diversity of Moniliophthora roreri from cacao trees growing in the Soconusco area, Chiapas, Mexico

Moniliophthora roreri (Cif.) Evans et al. is the causal agent of frosty pod rot or cacao moniliasis. This disease represents the main phytosanitary problem that cacao production faces in Latin America. The vastly destructive capacity of frosty pod rot conveys high economic losses. This study aimed to determine the genetic diversity of M. roreri associated with cacao trees growing around the Soconusco area in Chiapas, México, through the Inter-Simple Sequence Repeat analysis or ISSR. The study consisted of 145 strains of M. roreri isolated from 17 sites belonging to 12 regions in the Soconusco area, from Suchiate in the south, near the Guatemala border, to Acapetahua in the north of Chiapas. According to the analysis, two genetic groups were identified; the first one was located in the north of the Soconusco area, and the second in the south. The AMOVA analysis indicated high variability in the populations (59.64%), meaning among sampling sites that within them (40.35%), and together with the Mantel analysis (p = 0.034), it indicates that the gene flow of M. roreri is affected by landscape features, e.g., mountains, roads, and rivers.