Capability of phytoremediation of glyphosate in environment by Vulpia myuros.

Glyphosate is an herbicide extensively used worldwide that can remain in the soil. Phytoremediation to decontaminate polluted water or soil requires a plant that can accumulate the target compound. Vulpia myuros is an annual fescue that can be used as a heavy mental phytoremediation strategy. Recently, it has been used to intercrop with tea plant to prohibit the germination and growth of other weeds in tea garden. In order to know whether it can be used an decontaminating glyphosate' plant in water or soil, in this study, glyphosate degradation behavior was investigated in Vulpia myuros cultivated in a hydroponic system. The results showed that the concentration of glyphosate in the nutrient solution decreased from 43.09 µg mL-1 to 0.45 µg mL-1 in 30 days and that 99% of the glyphosate molecules were absorbed by V. myuros. The contents of glyphosate in the roots reached the maximum (224.33 mg kg-1) on day 1 and then decreased. After 3 days, the content of glyphosate in the leaves reached the highest value (215.64 mg kg-1), while it decreased to 156.26 mg kg-1 in the roots. The dissipation dynamics of glyphosate in the whole hydroponic system fits the first-order kinetic model C = 455.76e-0.21 t, with a half-life of 5.08 days. Over 30 days, 80% of the glyphosate was degraded. The contents of the glyphosate metabolite amino methyl phosphoric acid (AMPA), ranged from 0.103 mg kg-1 on day 1-0.098 mg kg-1 on day 30, not changing significantly over time. The Croot/solution, Cleaf/solution and Cleaf/root were used to express the absorption, transfer, and distribution of glyphosate in V. myuros. These results indicated that glyphosate entered into the root system through free diffusion, which was influenced by both the log Kow and the concentration of glyphosate in the nutrient solution, and that glyphosate was either easily transferred to the leaves through the transpiration stream, accumulated, or degraded. The degradation of glyphosate in V. myuros indicated that it has potential as a remediating plant for environmental restoration.

Integrated Metabolomic and Transcriptomic Analysis Reveals That Amino Acid Biosynthesis May Determine Differences in Cold-Tolerant and Cold-Sensitive Tea Cultivars.

Cold stress is one of the major abiotic stresses limiting tea production. The planting of cold-resistant tea cultivars is one of the most effective measures to prevent chilling injury. However, the differences in cold resistance between tea cultivars remain unclear. In the present study, we perform a transcriptomic and metabolomic profiling of Camellia sinensis var. "Shuchazao" (cold-tolerant, SCZ) and C. sinensis var. assamica "Yinghong 9" (cold-sensitive, YH9) during cold acclimation and analyze the correlation between gene expression and metabolite biosynthesis. Our results show that there were 51 differentially accumulated metabolites only up-regulated in SCZ in cold-acclimation (CA) and de-acclimation (DA) stages, of which amino acids accounted for 18%. The accumulation of L-arginine and lysine in SCZ in the CA stage was higher than that in YH9. A comparative transcriptomic analysis showed an enrichment of the amino acid biosynthesis pathway in SCZ in the CA stage, especially "arginine biosynthesis" pathways. In combining transcriptomic and metabolomic analyses, it was found that genes and metabolites associated with amino acid biosynthesis were significantly enriched in the CA stage of SCZ compared to CA stage of YH9. Under cold stress, arginine may improve the cold resistance of tea plants by activating the polyamine synthesis pathway and CBF (C-repeat-binding factor)-COR (cold-regulated genes) regulation pathway. Our results show that amino acid biosynthesis may play a positive regulatory role in the cold resistance of tea plants and assist in understanding the cold resistance mechanism differences among tea varieties.