Rotating and stacking genes can improve crop resistance durability while potentially selecting highly virulent pathogen strains

Rotating crop cultivars with different resistance genes could slow the evolution of virulent strains of fungal pathogens, but could also produce highly virulent pathogen strains. This paper presents a new model linking polycyclic pathogen epidemiology and population genetics to predict how different strategies of rotating cultivars with different resistances will affect the evolution of pathogen virulence and the breakdown of crop resistance. The model simulates a situation with four resistance genes and four virulence genes. Four rotational management strategies were simulated: (i) no rotation; (ii) a different gene every year; (iii) a different gene every 5 years; and (iv) a different combination of two stacked genes each year. Results indicate that rotating cultivars can lead to longer periods of disease suppression but also to the selection of highly virulent strains. The efficacy of different strategies depended on fitness penalties, initial virulence allele frequencies, and the ability of non-virulent pathogen genotypes to grow on resistant cultivars. The model provides a tool for investigating the evolutionary dynamics of pathogen virulence and crop resistance breakdown.

Rémi Crété, Rodrigo Neto Pires, Martin J. Barbetti, Michael Renton