Feng Zhao

Aryloxyphenoxypropionate (AOPP), a widely used class of herbicides, pose significant risks to ecosystems and human health. In this study, Bacillus amyloliquefaciens L1 was isolated as a novel degrader, completely degrading 97.42 mg/L cyhalofop-butyl within 12 h via ester bond hydrolysis to cyhalofop acid. A new carboxylesterase, PnbA, was identified from strain L1, showing substrate preference for cyhalofop-butyl > clodinafop-propargyl > haloxyfop-p-methyl > quizalofop-p-ethyl. Molecular docking and mutagenesis identified S190 as a key catalytic residue. Two mutants, K411A and T412A, exhibited enhanced relative activities toward both cyhalofop-butyl (124.08 and 153.16%, respectively) and quizalofop-p-ethyl (120.97 and 171.06%, respectively) due to accelerated substrate capture and improved binding affinity. Strain L1 effectively remediated cyhalofop-butyl from contaminated soil and water matrices in natural microbial backgrounds. Homologous protein analysis revealed an overwhelming bacterial origin (99.39%) versus archaea (0.61%). This study provides novel enzymatic resources for AOPP remediation and expands the understanding of its microbial genetic basis.

This study explored the role of Glycine betaine (GB) in mitigating atrazine (ATZ)-induced toxicity in soybean and investigated the underlying molecular mechanisms. In this study, GB significantly improved soybean growth under ATZ stress, increased antioxidant enzyme activity, and reduced oxidative damage. Further analysis demonstrated that GB markedly induced the soybean transcription factor GmMYB30 expression, which binds to the promoter of the key BL biosynthesis gene GmCYP85A2 and enhances its expression, thereby promoting BL synthesis. Overexpression of GmMYB30 increased endogenous BL levels, enhanced antioxidant enzyme activity, reduced reactive oxygen species (ROS) accumulation, and improved soybean tolerance to ATZ. More importantly, interference with GmMYB30 blocked GB-induced BL synthesis and eliminated the protective effect of GB against ATZ toxicity in soybean. These findings indicate that GB regulates GmCYP85A2 expression by inducing GmMYB30, increases endogenous BL content, activates antioxidant enzyme activity, scavenges ROS, and ultimately enhances soybean tolerance to ATZ.

BACKGROUND: Flusulfinam, a novel chiral herbicide, effectively controls Echinochloa crusgalli and Digitaria sanguinalis in paddy fields, indicating significant potential for practical agricultural applications. However, limited information is available on flusulfinam from a chiral perspective. A comprehensive evaluation of the enantiomeric levels of flusulfinam was performed.RESULTS: Two enantiomers, R‐(+)‐ and S‐(−)‐flusulfinam, were separately eluted using a Chiralcel OX‐RH column. The bioactivity of R‐flusulfinam against the two was 1.4–3.1 fold that of Rac‐flusulfinam against two weed species. R‐flusulfinam toxicity to Danio rerio larvae and Selenastrum capricornutumwere was 0.8‐ and 3.0‐fold higher than Rac‐flusulfinam, respectively. Degradation experiments were conducted using soil samples from four Chinese provinces. The findings indicated that S‐flusulfinam (half‐life T_1/2 = 40.8 days) exhibits preferential degradation than R‐flusulfinam (T_1/2 = 46.2–57.8 days) in the soils of three provinces. Under anaerobic conditions, soil from Anhui exhibited preferential degradation of R‐flusulfinam (T_1/2 = 46.2 days) over S‐flusulfinam (T_1/2 = 63 days). Furthermore, two hydrolysis products of flusulfinam (M299 and M100) are proposed for the first time.CONCLUSION: The enantioselective bioactivity, toxicity and degradation of flusulfinam were investigated. Our findings indicate that R‐flusulfinam is an extremely effective and low‐toxicity enantiomer for the tested species. The soil degradation test indicated that the degradation of flusulfinam was accelerated by higher organic matter content and lower soil pH. Furthermore, microbial communities may play a crucial role in driving the enantioselective degradation processes. This study lays the groundwork for the systematic evaluation of flusulfinam from an enantiomeric perspective. © 2024 Society of Chemical Industry.