Towards Uncovering New Insights into Respiratory Inhibitor Fungicide Resistance in Molinia Fungal Plant Pathogens: Insights from a Mitogenomic Approach

Mitochondrial genomes are key targets in controlling fungal plant pathogens and mediate adaptive responses like fungicide resistance. Respiratory inhibitor fungicides (RIs) are widely used against many fungal pathogens, including Monilia fructi cola and M. lax, which are casual agents of brown rot of stone fruits worldwide. Although resistance to RIs has been reported in these species, the genetic basis is not fully elucidated. and is hypothesized to involve mitochondrial genome variations. To explore this, mitogenomic variations was comprehensively analysed to assess the resistance responses of two Monilia species to three RIs, including two technical grade fungicides (bosclid and azoxystrobin) and, a commercial one (signum). Whole mitogenome data from sixteen isolates of two species with different resistance/susceptibility phenotypes were analysed for certain gene mutations, mitochondrial variants, heteroplasmy, and sequence kernel associations. The results indicated that commonly known mutations and low levels of heteroplasmy do not fully explain resistance. In Monilinia fructicola, the presence of multiple variants appears to contribute to resistance, however, no variant patterns corresponded significantly with resistance phenotype in M. laxa. Providing a broad perspective, this study serves as a valuable model and supports the potential of mitogenome-focused RI resistance research. These insights contribute to a better understanding of specific resistance responses, thereby supporting the development of more effective pathogen control strategies.