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 (cacao moniliasis). This disease represents the main phytosanitary problem that cacao production faces in Latin America. The vast destructive capacity of frosty pod rot leads to 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, Mexico, through the inter simple sequence repeat analysis or ISSR. The study analyzed 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 results of 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 analysis of molecular variance (AMOVA) indicated higher variability in the populations (59.64%) among sampling sites than within the populations (40.35%), and together with the Mantel analysis (P = 0.034), it indicated that the gene flow of M. roreri is affected by landscape features, such as mountains, roads, and rivers.