Chiral Herbicide Fluorochloridone: Absolute Configuration, Stereoselective Bioactivity, Toxicity, and Degradation in the Potatoes.

Fluorochloridone (FLC) is a chiral herbicide that has four stereoisomers. This study systematically assessed the stereoselectivity of FLC to reveal the selective environmental behavior of its four isomers. Absolute configuration confirmation, evaluation of stereoselective bioactivity toward monocotyledonous and dicotyledonous weeds, toxicity to Danio rerio, and the stereoselective degradation in the potato system under field conditions of FLC were conducted. The four FLC stereoisomers were effectively separated on a superchiral S-AD column. The absolute configurations of the four stereoisomers of FLC were confirmed as (-)-(3S, 4S), (+)-(3S, 4R), (-)-(3R, 4S), and (+)-(3R, 4R)-FLC using single-crystal X-ray diffraction. The activities of the four stereoisomers were in the order of (-)-(3S, 4S)-FLC > (+)-(3R, 4R)-FLC > (+)-(3S, 4R)-FLC > (-)-(3R, 4S)-FLC, and the rate of selective degradation were in the order of (-)-(3R, 4S)-FLC > (+)-(3R, 4R)-FLC > (-)-(3S, 4R)-FLC > (+)-(3S, 4S)-FLC. The toxicity of the isomers were in the order of (-)-(3R, 4S)-FLC > (+)-(3R, 4R)-FLC > (-)-(3S, 4S)-FLC > (+)-(3S, 4R). Based on the results of bioactivity, toxicity, and degradation behavior assessments, the stereoisomer mixture containing (3R,4R)-FLC and (3S,4S)-FLC was concluded to be a better option than racemic FLC for increasing bioactivity and reducing usage.

Integrated transcriptomic and metabolomic analyses of the molecular mechanisms of two highland barley genotypes with pyroxsulam responses.

Highland barley is one of the few crops that can be grown at high elevations, making it a key resource within the Tibet Plateau. Weeds are a significant threat to highland barley production, and new herbicides and tolerant barley varieties are needed to control this ever-growing problem. A better understanding of existing herbicide resistance mechanisms is therefore needed. In this study, transcriptomic and metabolomic analyses were used to identify molecular and physiological changes in two highland barley genotypes with differing sensitivities to the herbicide pyroxsulam. We identified several stress-responsive metabolites, including flavonoids and antioxidants, which accumulated to significantly higher levels in the pyroxsulam-resistant genotype. Additionally, we found key genes in both the flavonoid biosynthesis pathway and the antioxidant system that were up-regulated in pyroxsulam-resistant barley. This work significantly expands on the current understanding of the molecular mechanisms underlying differing pyroxsulam tolerance among barley genotypes and provides several new avenues to explore for breeding or engineering tolerant barley.

Residue, dissipation, and safety evaluation of etoxazole and pyridaben in Goji berry under open-field conditions in the China's Qinghai-Tibet Plateau.

The dissipation and residual levels of etoxazole and pyridaben in Goji berry under open field conditions were determined by using GC-NPD (gas chromatography with nitrogen and phosphorus detector) with modified QuEChERS method. At fortification levels of 0.01, 1, and 5 mg/kg in Goji berry, it was shown that recoveries were ranged from 80.40 to 100.9% with relative standard deviation of the method (RSD) for repeatability ranged from 2.20 to 4.25%. The limit of quantification (LOQ) of the method was 0.01 mg/kg. The dissipation rates of etoxazole and pyridaben were described by using first-order kinetics and its half-life, as they are 7.13 days, 5.77 days, and 5.99 days (etoxazole) and 1.02 day, 0.67 day, 1.02 day (pyridaben). The terminal residues of etoxazole and pyridaben were below the European maximum residue limit (MRL, 0.1 mg/kg) in Goji berry when measured 7 days after the final application, which suggested that the use of these insecticides was safe for humans. This study would help in providing the basic information for developing regulation to guard a safe use of etoxazole and pyridaben in Goji berry and prevent health problem from consumers.