The Clearfield((R)) technology is an useful tool for controlling weedy rice due to the effectiveness of imazamox and the cultivation of rice varieties resistant to imidazolines. However, residual imazamox in the soil probably causes phytotoxicity to subsequent non-resistant rice crops. We previously found that pyrroloquinoline quinone (PQQ), a bioactive elicitor, can enhance rice tolerance to imazamox. In this study, we explored the molecular mechanism of PQQ-mediated rice tolerance to imazamox by RNA-seq analysis, real-time quantitative PCR (RT-qPCR) assay, and enzyme activity assay. The results indicated that compared to imazamox at 66.7 mg a.i./L (IMA) alone, rice plants treated with imazamox at 66.7 mg a.i./L and PQQ at 0.66 mg a.i./L (IMA + PQQ) exhibited significantly reduced sensitivity to imazamox. Seven days post-treatment, IMA + PQQ-treated rice plants showed partial chlorosis and leaf curling, but IMA-treated rice plants had severe wilting and died. The fresh weight inhibition rate was 29.3% in the IMA + PQQ group, significantly lower than that of 56.6% in the IMA group alone. RNA-seq analysis showed differentially expressed genes were mainly involved in phenylpropanoid biosynthesis, diterpenoid biosynthesis, and MAPK signaling pathways in response to IMA + PQQ treatment. Both RNA-seq analysis and RT-qPCR assay showed that the expression of OsCATB gene in the catalase (CAT) gene family was upregulated at 12 h, the expression of OsGSTU1 gene was upregulated at 12, 24, and 48 h, while the expressions of OsABCB2, OsABCB11, and OsABCG11 genes were upregulated at 24 and 48 h. Enzyme activity assays revealed that the activity of superoxide dismutase in the IMA + PQQ group was increased by 47.45 similar to 120.31% during 12 similar to 72 h, compared to that in the IMA group. CAT activity in the IMA + PQQ group was increased by 123.72 and 59.04% at 12 and 48 h, respectively. Moreover, malondialdehyde levels indicative of oxidative damage were consistently lower in IMA + PQQ-treated plants, with a reduction of 46.29, 11.37, and 14.50% at 12, 36, and 72 h, respectively. Overall, these findings discover that PQQ has potential in reducing imazamox phytotoxicity in rice by enhancing antioxidant enzyme activities and regulating oxidative stress responses. They will provide valuable strategies for improving imazamox tolerance in crops.

Pesticides are chemical substances that have become essential for global food production. However, their extensive use has resulted in significant environmental and health costs. Among the most widely used are diazinon and methamidophos, an insecticide and acaricide, respectively. These chemicals are classified as highly hazardous with high toxicity upon contact, ingestion, and inhalation. They are known to cause mutagenic effects, cancer, damage to the endocrine and nervous systems of humans, and their high solubility makes them likely to be found in soil, water, air, and certain foods. In this research, we evaluated the use of the microalga Chlorella vulgaris for phycoremediation of these two pesticides. The first step was to establish and optimize the growth parameters of C. vulgaris to maintain the microalgae in a state of reproduction. Favorable results were obtained at pH 7.0, a dilution ratio of 1:2 for the culture medium, and a photoperiod of 12 h of light and 12 h of darkness. Subsequently, the Minimum Inhibitory Concentration (MIC) and the Half-Maximal Effective Concentration (EC50) of the pesticides diazinon and methamidophos were evaluated. The microalga exhibited a high tolerance rate, with concentrations exceeding those naturally found in the environment. Based on these results, the conditions for assessing the biodegradation of both pesticides by the microalga were established. The outcome showed degradation percentages of 96 % for diazinon (25 mg L-1) and 100 % for methamidophos (500 mg L-1). In addition, the analysis of intermediate metabolites during the biodegradation process of both pesticides revealed the formation of less toxic compounds compared to the precursors and possibly complete mineralization as well; this given the positive response in terms of inorganic phosphate generation during the degradation. Finally, we propose biodegradation pathways for methamidophos and diazinon based on the detected metabolites and available information on biodegradation by certain bacteria.

Farmland soil organisms frequently encounter pesticide mixtures presented in their living environment. However, the underlying toxic mechanisms employed by soil animals to cope with such combined pollution have yet to be explored. This investigation aimed to reveal the changes in cellular and mRNA levels under chlorpyrifos (CPF) and lambda -cyhalothrin (LCT) co-exposures in earthworms ( Eisenia fetida ). Results exhibited that the combination of CPF and LCT triggered an acute synergistic influence on the animals. Most exposures resulted in significant alterations in the activities of total superoxide dismutase (T -SOD), copper/zinc superoxide dismutase (Cu/Zn-SOD), caspase 3, and carboxylesterase (CarE) compared to the basal level. Moreover, when exposed to chemical mixtures, the transcription levels of four genes [heat shock protein 70 ( hsp70 ), gst , sod , and calreticulin ( crt )] also displayed more pronounced changes compared with their individual exposures. These changes in determined parameters indicated the occurrence of oxidative stress, cell death, detoxification dysfunction, and endoplasmic reticulum damage after co-exposure to CPF and LCT in E. fetida . The comprehensive examination of mixture toxicities of CPF and LCT at different endpoints would help to understand the overall toxicity they cause to soil invertebrates. The augmented deleterious effect of these pesticides in a mixture suggested that mixture toxicity assessment was necessary for the safety evaluation and application of pesticide mixtures.

The soil quality index (SQI) is a comprehensive indicator that reflects the agricultural productivity of soil, as well as playing important roles in understanding microbial nutrient metabolism and carbon use efficiency (CUE). However, it is unclear how drip irrigation treatments in apple orchards affect the SQI, eco-enzyme stoichiometry, and soil microbial CUE. Thus, in the present study, we tested three different treatments in orchard plots: T1 (50-60 % field water capacity (theta f)), T2 (65-75 % theta f), and T3 (80-90 % theta f), as well as control with no drip irrigation (CK). The study focused on the effects of these treatments during two key stages: bud breaking and fruit maturity. During the bud breaking stage, we observed that water availability had a more pronounced influence on the SQI when soil moisture was limited. Specifically, in the 0-20 cm soil layer, the T2 treatment showed a significantly lower SQI value compared to T3, with a decrease of 31.89 %. On the other hand, there were no significant differences among all the irrigated treatments during the maturity stage. Both vector length and angle were significantly affected by water availability during the bud breaking stage, while only the vector angle was impacted during the maturity stage. The vector length and angle were both influenced by SQI (Mantel's test: p < 0.01). During the bud breaking stage, the CUE values in 0-20 cm layer under T1, T2, and T3 were 30.27 %, 21.79 %, and 85.47 % lower, respectively, compared with CK. By contrast, in the fruit maturity stage, CUE was 27.39 % higher under T1 compared with CK. SQI and CUE had a negative correlation in the bud breaking stage (p < 0.001, R-2 = 0.26), but a positive correlation in the fruit maturity stage (p < 0.001, R-2 = 0.51). Our findings suggest that the T3 treatment consistently yields the highest Soil Quality Index (SQI) across most soil layers during the bud breaking and maturity stages. Moreover, the T3 treatment effectively alleviates early spring drought in the Weibei region and encourages deep-root development, enabling fruit trees to absorb nutrients from deeper soil levels. Overall, these findings enhance our understanding of how the SQI and enzyme stoichiometry under drip irrigation affect phosphorus and carbon metabolism in soils, and they suggest that SQI should be considered a key factor that limits microbial metabolic restrictions and microbial CUE.