Exogenous silicon enhances resistance to 1,2,4-trichlorobenzene in rice

The decrease in panicle number is the main reason for the yield reduction of japonica rice caused by 1,2,4-trichlorobenzene stress

Persistent organic pollutants seriously affect the growth and development of crops. 1,2,4-Trichlorobenzene (TCB), as one of the most widely used chlorobenzenes, can affect the yield of japonica rice. However, existing research on the effect of TCB on japonica rice yield is not in-depth, and a basic understanding of commonality has not yet been formed. In this study, 28 conventional japonica rice varieties were selected to investigate the effects of TCB stress on their yield, yield composition, and TCB accumulation. This study also evaluated the efficiency of conventional tolerance indices in evaluating the TCB stress tolerance of japonica rice. The results showed that TCB caused sustained inhibition of the growth of japonica rice, which was considerably manifested in plant height, root length, soil plant analysis development (SPAD), and dry weight at different growth stages. Under TCB stress, TCB accumulation in various tissues of japonica rice increased sharply. TCB stress reduces the yield of japonica rice by reducing the number of panicles per hill, the number of spikelets per panicle, the grain filling percentage, and the grain weight. Overall, the results of this study indicate that TCB stress can cause a decrease in the yield of japonica rice, and the decrease in panicle number is the main reason. The conventional tolerance index can effectively evaluate the tolerance of japonica rice to TCB. The results of this study are substantial for the breeding and cultivation of japonica rice.

Straw incorporation induces rice straighthead disease in As-contaminated paddy soil

Rice straw incorporation is globally recognized as a viable alternative to incineration. However, it might lead to arsenic (As) methylation in soils, resulting in increased accumulation of methylated As in rice plants, potentially contributing to the emergence of rice straighthead disease. To evaluate the effect of straw incorporation on the As transformation in the paddy field system, we conducted a pot experiment for rice cultivation in two paddy soils with different As background levels and also characterized the response of the soil microbial community to straw incorporation. The results showed that straw incorporation elevated the total and methylated As concentration within the soil solution and rice plants, which in turn reduced rice seed setting rate and yield, and caused straighthead disorder in rice cultivated in soils with high As levels. 16S rRNA-based sequencing demonstrated reduced abundance and diversity of microorganisms upon adding straw. Notably, the dominant phylum, Bacteroidetes, exhibited a significant increase in abundance due to straw integration, while the abundance of Proteobacteria and Acidobacteria decreased. At the family level, the prevalence of Rikenellaceae increased only in soils contaminated with As following straw incorporation. Redundancy analysis showed positive associations between Rikenellaceae and levels of methylated As present in both soil porewater and rice husks, suggesting a potentially pivotal role of Rikenellaceae in the As methylation process after straw integration. These findings collectively emphasize that including straw can reshape the soil's microbial community and amplify As methylation in the soil, thereby promoting the uptake and accumulation of methylated As in rice and inducing straighthead disease in As-contaminated soil.

Interpretation of ametryn biodegradation in rice based on joint analyses of transcriptome, metabolome and chemo-characterization

Agrochemicals such as pesticide residues become environmental contaminants due to their ecotoxic risks to plant, animal and human health. Ametryn (AME) is a widely used farmland pesticide and its residues are widespread in soils, surface stream and groundwater. However, its toxicological and degradative mechanisms in plants and food crops are largely unknown. This study comprehensively investigated AME toxicology and degradation mechanisms in a paddy crop. AME was freely absorbed by rice roots, translocated to the above-ground and thus repressed plant elongation, and reduced dry weight and chlorophyll concentration, but increased oxidative injury and subcellular electrolyte permeability. Analysis of the transcriptome and metabolome revealed that exposure to AME evoked global AME-responsive genes and step-wise catabolism of AME. We detected 995 (roots) and 136 (shoots) upregulated and differentially expressed genes (DEGs) in response to AME. Metabolomic profiling revealed that many basal metabolites such as carbohydrates, amino acids, glutathione, hormones and phenylpropanoids involved in AME catabolism were accordingly accumulated in rice. Eight metabolites and twelve conjugates of AME were characterized by HPLC-Q-TOF-HRMS/MS. These AME metabolites and conjugates are closely related to DEGs, differentially accumulated metabolites (DAMs) and activities of antioxidative enzymes. Collectively, our work highlights the specific mechanisms for AME degradative metabolism through Phase I and II reactive pathways (e.g. hydroxylation and dealkylation), with will help develop genetically engineered rice used to bioremediate AME-contaminated paddy soils and minimize AME accumulation rice crops.

Study on Degradation of 1,2,4-TrCB by Sugarcane Cellulose-TiO2 Carrier in an Intimate Coupling of Photocatalysis and Biodegradation System

1,2,4 trichlorobenzene (1,2,4-TrCB) is a persistent organic pollutant with chemical stability, biological toxicity, and durability, which has a significant adverse impact on the ecological environment and human health. In order to solve the pollution problem, bagasse cellulose is used as the basic framework and nano TiO₂ is used as the photocatalyst to prepare composite carriers with excellent performance. Based on this, an intimate coupling of photocatalysis and biodegradation (ICPB) system combining photocatalysis and microorganisms is constructed. We use the combined technology for the first time to deal with the pollution problem of 1,2,4-TrCB. The biofilm in the composite carrier can decompose the photocatalytic products so that the removal rate of 1,2,4-TrCB is 68.01%, which is 14.81% higher than those of biodegradation or photocatalysis alone, and the mineralization rate is 50.30%, which is 11.50% higher than that of photocatalysis alone. The degradation pathways and mechanisms of 1,2,4-TrCB are explored, which provide a theoretical basis and potential application for the efficient degradation of 1,2,4-TrCB and other refractory organics by the ICPB system.

Effects of Rice-Husk Silica Liquid in Streptozotocin-Induced Diabetic Mice

Type 2 diabetes mellitus is a complex multifactorial disease characterized by poor glucose tolerance and insulin resistance. Rice-husk silica liquid (RHSL) derived from rice husk has the ability to improve the dysfunction of pancreatic β-cells. This study aimed to confirm the potential protective effects of RHSL in streptozotocin (STZ)-induced diabetic mice. Diabetes was induced in male C57BL/6J mice by intraperitoneal administration of STZ (200 mg/kg BW). RHSL, food-grade silica liquid (FDSL), and rosiglitazone (RSG) were administered to diabetic mice for 12 weeks after successful induction of diabetes. During the experiment, fasting blood glucose, serum insulin, and organ weights were measured. The histopathology of liver tissue was evaluated by H&E staining. Western blotting was performed to assess protein expression levels. The results showed that RHSL significantly reversed the serum insulin levels and improved oral glucose tolerance test (OGTT) results (p < 0.05). In addition, liver sections of STZ-induced diabetic mice after RHSL treatment showed neatly arranged and intact hepatocytes. Furthermore, RHSL was more effective than FDSL in increasing the expression of SIRT1 and decreasing the expression of the PPAR-γ and p-NF-κB proteins. Taken together, this study demonstrated that RHSL ameliorated STZ-induced insulin resistance and liver tissue damage in C57BL/6J mice.