Rise and Fall of Phytophthora infestans Resistance to Non-Specific Fungicide in Experimental Populations.

Background: Fungicide resistance is one of the major factors threatening social and ecological sustainability. Many issues associated with the evolutionary processes and mechanisms of fungicide resistance in pathogens remain poorly understood, and better knowledge of these issues through experimentally observing the rise and fall of the resistance is critical for the development of effective management strategies to ensure food security and ecological health. Methods: An experimental evolution approach was used to continuously acclimate a series of Phytophthora infestans populations under different mancozeb conditions for 400 consecutive days. Results: We found that P. infestans developed mancozeb resistance after 200 days of acclimation. This resistance was associated with ABC transporters and endocytic proteins. Potentially due to fitness costs associated with aggressiveness, mancozeb resistance was reversible. And the pathogen exhibited comparable rates of resistance gain during acclimation and resistance loss during the reversal experiment. Conclusions: Our results suggest that this pathogen may also develop resistance to mancozeb. However, this type of resistance may not be persistent, implying the fungicides concerned could be reused in practice. These results provide new insights into the evolution of fungicide resistance and sustainable plant disease chemical management based on the fungicide dose chosen beyond that of potato blight, warranting further study on the resistance target gene.