Rational application of QoIs fungicides to achieve a rice-fungi-fish interaction balance within paddy ecosystems

In the realm of agricultural chemical research, elucidating the mechanisms underlying the selectivity of quinone outside inhibitors (QoIs) is crucial for guiding the development of novel pesticides. In this study, differences in the selectivity and toxicity of 12 QoIs were evaluated using three organisms (Magnaporthe oryzae, zebrafish, and rice) present in paddy fields. The interplay between the specific mechanisms of QoIs selectivity among different organisms and the variations in individual toxicity remains unclear. Therefore, the distinct levels of enrichment behavior, cell toxicity, and target enzyme toxicity of 12 QoIs across three organisms were investigated in this research. Additionally, an attempt was made to analyze the correlation between structural parameters and the degree of toxicity at the tissue, cellular, and target levels to establish the regulatory direction of QoIs activity and toxicity. The results revealed that cytotoxicity and target enzyme toxicity played significant roles in the toxicity observed in individuals, specifically in fish and fungus, respectively. The results of this study revealed a significant negative correlation between the bioconcentration factor (BCF) in biological tissues and fish toxicity (LC₅₀) (P < 0.05), but no significant correlation between BCF of fungus and fungitoxicity (EC₅₀) was detected (P > 0.05). Reducing the Log P (octanol-water partition coefficient) and further changing tissue enrichment could balance the toxicity and activity of QoIs in organisms. On the basis of the aforementioned findings, introducing hydrophilic groups into the structure of pyraclostrobin with lower Log P values was an effective strategy for designing new QoI structures. These modified structures demonstrated reduced toxicity to fish and promising fungitoxicity against rice blast fungus compared with pyraclostrobin. This study provides valuable insights for regulatory measures in the design and development of effective and safe new QoIs in paddy fields, further reducing adverse impacts on paddy fields and aquatic ecosystems.