Fitness of homothallic and heterothallic isolates of Phytophthora infestans from Mexico

Phytophthora infestans is an important pathogen of potato and tomato worldwide. Knowledge of the fitness components (FCs), such as pathogenicity, virulence, latent period, lesion area and sporulation of isolates with different mating types from the same region, is important for improved understanding of the evolutionary potential of P. infestans and its short- and long-term management. The FCs and a Compound Biological Fitness Index (CBFI) of 12 strains of P. infestans collected from the central area of Mexico, with different mating types (A1, A2 and self-fertile), were compared under controlled conditions in growth chambers. All P. infestans strains were pathogenic, indicating that the conditions of the bioassays were adequate for disease development. FCs varied significantly among and within the three mating types, indicating that each group maintains substantial levels of genetic variation among and within isolates. The self-fertile group was significantly more fit in all FCs and CBFI, followed by groups A2 and A1. These results indicate that self-fertile strains are the most aggressive and have the greatest evolutionary potential in central Mexico. All FCs showed significant correlations with one another, indicating that these parameters can be used to estimate the biological fitness of P. infestans. These results provide fundamental information for the integrated management of this pathogen in central Mexico, as well as for understanding its evolutionary potential.

Automated summary

This study compared the fitness components and Compound Biological Fitness Index (CBFI) of different mating types of P. infestans strains collected from central Mexico, and found that self-fertile strains were more fit in all fitness components. These results provide valuable information for the management and understanding of the evolutionary potential of this pathogen.