Herbicide Resistance and soil microbial composition

The following contribution reports the main results of a research titled “Incidence of resis- tance to ALS and ACCase inhibitors in Echinochloa species and soil microbial composition in Northern Italy” recently published on Scientific Reports Journal. This contribution is part of the project NODES which is funded by the European Union - NextGenerationEU, Mission 4 Component 1.5 - ECS00000036 - CUP F17G22000190007. Herbicide resistance represents a serious problem for crop management, leading to important yield losses every year. The relation between soil microbial communities and herbicide resistance occurrence is a still poorly known topic. Its investigation would be crucial to better understand potential relapses on agricultural management. The microbiome of soils collected in 32 rice farms located in the Northern Italy (Lombardy) was analyzed, aiming to evaluate the relationship between the microbial composition and the incidence of resistance to acetolactate synthase (ALS) and acetyl-CoA carboxylase (ACCase) inhibiting herbicides in Echinochloa species. A relation be- tween the soil microbiomes diversity and the abundance of weeds survived chemical control was observed. A low microbial diversity was recorded in highly infested paddies (resistant Echinochloa coverage ≥ 60%) while a high microbial diversity was recorded in poorly infested paddies (resistant Echinochloa coverage ≤ 5%). Fungal communities showed a greater re- duction in richness than bacterial ones and a stronger relation with herbicide resistance in paddies where a high incidence of resistant Echinochloa species was observed. In soils with a low microbial diversity, a significant dominance of some bacterial and fungal orders (i.e. Lactobacillales, Malasseziales and Diaporthales) was observed. In general, two different mi- crobial profiles related to the high or low incidence of herbicide resistance by Echinochloa species were identified. The results of this research allow to make hypotheses on the greater or lesser probability of herbicide resistance occurrence based on the composition of the soil microbiome and especially on the degree of biodiversity of the microbial communities.