Though responses to Cd in rice (Oryza sativa L.) have been well established, there are few reports about the different effects of short-term exposure to Cd between the subspecies indica ('Kasalath' variety) and japonica ('Nipponbare' variety). We observed similar Cd accumulation and root damage in roots of two varieties under 6 h Cd stress, but KEGG pathway analysis of transcriptome data revealed that pathways involved in different metabolic processes were affected. Among them, antioxidant enzyme system was involved in Cd detoxification in 'Nipponbare' variety, whereas GSH metabolism played important roles in 'Kasalath' variety. From the results of physiological experiments, extremely higher activity of SOD, POD, and CAT was observed in 'Nipponbare' variety after a short-term exposure to Cd. At the same time, the immediate Cd-induced stimulation of Cys and PCs were observed in 'Kasalath' variety along with the enlargement of vacuoles. This study provides an overview of main responses to short-term Cd stress and identifies potential target genes that may contribute to the different mechanisms of Cd stress-resistance in roots of japonica subspecies and indica subspecies.

Herbicide is indispensable for crop production. However, substantial usage of herbicide has led to its increasing accumulation in soils and crops. In addition, cadmium has become one of the widely occurring contaminants in soils due to its significant release into environment via anthropogenic activities. In this study, ecotoxicological investigations were made by exposing the food crop wheat to joint contaminations of Cd and metsulfuron-methyl, a sulfonylurea herbicide. We analyzed growth and physiological and molecular responses in wheat exposed to 0.5 mg kg−1 Cd and 0.02 mg kg−1 metsulfuron-methyl (MSM). Soils contaminated with Cd and MSM complex caused significantly detrimental effect on wheat growth and physiological process. Combinative treatments with Cd and MSM damage more severely the plant cells as compared with Cd or MSM treatment alone. Compared with the growth parameter, the biochemical and molecular responses of wheat appeared more pronounced to Cd and MSM complex. Furthermore, compared with control, wheat plants exposed to Cd + MSM generated more O2−.and H2O2, both of which were shown to be the cause of enhanced activity of several antioxidant enzymes. Native polyacrylamide gel eletrophoresis and molecular response analyses were performed to validate the results indicated above. Our results indicated that joint contamination with Cd and MSM was more toxic to wheat than a single contamination. These sensitive biological parameters can be used as biomarkers monitoring the ecotoxicological process in plants.

Isoproturon, a herbicide belonging to the phenylurea family, is widely used to kill weeds in soils. Recent study indicated that isoproturon has become a contaminant in ecosystems due to its intensive use, thus bringing environmental risks to crop production safety. Salicylic acid (SA) is one of the components in plant defense signaling pathways and regulates diverse physiological responses to biotic and environmental stresses. The purpose of the study is to help to understand how SA mediates the biological process in wheat under isoproturon stress.

Incorporation of organic fertilizers/amendments in soils has been, and will continue to be, a popular strategy for improving the quality of arable soils. However, the mechanism by which the dissolved organic matters (DOMs) affect soil properties or interact with other substances in soils is largely unknown. In this study, a batch equilibrium experiment was performed to evaluate the effect of two types of DOMs on the behavior of prometryne (a herbicide) in soils. Two sorts of DOMs were derived from lakebed sludge (SL) and rice straw (ST), respectively. The results show that sorption capacity in one soil for prometryne was significantly reduced by application of DOMs, whereas desorption of prometryne was promoted by DOM treatments. To understand the mobility behavior of prometryne in soils with DOMs, a column leaching experiment was carried out. It is shown that both DOMs enhanced the solubility and migration of prometryne in soils. To confirm the role of DOMs in regulating the mobility of prometryne in soils, a soil thin-layer chromatography was performed. The migration of prometryne was promoted by DOMs, which were used as a developing solvent or directly incorporated in the soil thin layer. The data indicate that DOM extracts can modify the mobility of prometryne in soil.