Mitochondrial heteroplasmy as a transitional state in the evolution of fungicide resistance.

Transient mitochondrial heteroplasmy in Zymoseptoria tritici enables rapid switching between fungicide resistance genotypes, with alleles G143A and Y132C coexisting within individual cells.

• Why it matters: Understanding mitochondrial genome dynamics is crucial because resistance mutations in the mitochondrial gene cytochrome b are key to fungicide resistance in fungal pathogens, yet their stability and behavior are poorly understood.
• What they did: The study used experimental evolution and single-cell analysis to observe heteroplasmic states where resistance alleles coexist at variable ratios, and tracked how allele dominance shifts under fungicide pressure, leading to homoplasmy.
• The result: Findings show that heteroplasmy is a transient, unstable state that facilitates resistance genotype switching, providing new insights into mitochondrial genome behavior and its role in microbial adaptation to fungicides.