Does the Metabolome of Wild-like Dendrobium officinale of Different Origins Have Regional Differences?

Dendrobium officinale, as a traditional Chinese medicine, has considerable commercial value and pharmacological activity. Environmental factors of different origins have a great influence on Dendrobium officinale metabolites, which affect its pharmacological activity. This study sought to identify the differential metabolites of wild-imitating cultivated D. officinale stems of different origins. Using the widely-targeted metabolomics approach, 442 metabolites were detected and characterized, including flavonoids, lipids, amino acids and derivatives, and alkaloids. We found that although the chemical constitution of D. officinale cultured in the three habitats was parallel, the contents were significantly different. Meanwhile, the KEGG pathway enrichment analysis revealed that the distinctive metabolites among the three groups were mainly involved in flavone and flavonol biosynthesis. To further explore the different contents of flavonoids, HPLC was performed on four main flavonoid contents, which can be used as one of the references to distinguish D. officinale from different growing origins. In conclusion, a comprehensive profile of the metabolic differences of D. officinale grown in different origins was provided, which contributed a scientific basis for further research on the quality evaluation of D. officinale.

Phosphorus sorption capacity of various iron-organic matter associations in peat soils.

This study was carried out to evaluate the contribution of different types of iron-organic matter associations (Fe-OM) to the phosphorus sorption capacity of peatland. Humic substance (HS) and particulate organic matter (POM) were isolated from peat soils, and different types of iron-organic matter associations (Fe-HS and Fe-POM) were prepared. Then, isothermal adsorption experiments were carried out on the synthesized Fe-OM and iron-contained peat soils. The morphology structure of Fe-HS associations is amorphous like that of ferrihydrite. The theoretical maximum adsorption capacity (Qmax) of Fe-HS associations can reach 36.90 mg/g, which is approximately two times higher than that of ferrihydrite (19.23 mg/g) and ten times higher than that of hematite (3.26 mg/g) and goethite (2.08 mg/g). Both peat soils and POM can strongly complex ferric ions, resulting in improved phosphorus sorption capacity. The Qmax of original peat soil and POM is 2.83 mg/g and 4.31 mg/g, which increased to 7.36 mg/g and 5.89 mg/g, respectively, after complexing ferric ions. Compared to inorganic Fe minerals, the associations of iron and organic matter (HS and POM) contribute more to the phosphorus retention ability of peat soils. However, the formation of Fe-OM associations could not fully explain why the addition of iron increases the phosphorus sorption capacity of peat soil by so much. Iron should also participate in other phosphorus retention processes, which need further exploration and research.

Linking microbial community composition to farming pattern in selenium-enriched region: Potential role of microorganisms on Se geochemistry.

Selenium (Se) is an essential micronutrient for lives. Indigenous microbial communities play an important role on Se geochemistry in soils. In this study, the microbial community composition and functions of 53 soil samples were investigated using high-throughput sequencing. Samples were divided into 3 groups with different farming types based on the measured geochemical parameters and microbial functional structures. Results indicated that putative Se related bacteria Bacillus, Dyella, Paenibacillus, Burkholderia and Brevibacillus were dominant in dryland plantation soils which were characterized with higher available Se and low contents of H2O, total organic carbon (TOC), NH4+ and NO2-. In contrast, the putative denitrifier Pseudomonas dominated in flooded paddy soils with higher TOC, NO3- and organic Se, whereas genera Rhizobium, Nitrosospira, and Geobacter preferred woodland soils with higher oxidation-reduction potential (ORP), pH, NH4+ and Fe. Farming patterns resulted in distinct geochemical parameters including moisture, pH, ORP, TOC, and contents of soluble Fe, NO2- and NH4+, shaping the microbial communities, which in turn affected Se forms in soils. This study provides a valuable insight into understanding of Se biogeochemistry in soils and prospective strategy for Se-rich agriculture production.

Two new selenite reducing bacterial isolates from paddy soil and the potential Se biofortification of paddy rice.

Selenium (Se) is an essential element for human health. Se-enriched agricultural products can promote people's intake of Se. Microorganisms play an important role in Se cycling. In this study, two new bacterial strains were isolated from paddy soil and were identified as Chitinophaga sp. and Comamonas testosteroni, respectively. More than 44% and 39% of 1.0 mM selenite were reduced in 84 h by them using yeast extract as carbon source, respectively. Scanning electron microscope (SEM) and Energy dispersive X-ray spectrometry (EDS) results indicated that the reduction product of selenite was nanometer Se. These strains could promote the available Se in soil and the content of Se in rice plants in pot experiments. Organic combined Se in soils was increased up to 35%, accompanied by the 92% and 130% increase of Se in rice plants. To our best knowledge, this is the first report of Se reduction by Chitinophaga. This work might provide a prospective strategy for microbial fortification of Se in corps.

Brassinosteroid Ameliorates Zinc Oxide Nanoparticles-Induced Oxidative Stress by Improving Antioxidant Potential and Redox Homeostasis in Tomato Seedling.

In the last few decades use of metal-based nanoparticles (MNPs) has been increased significantly that eventually contaminating agricultural land and limiting crop production worldwide. Moreover, contamination of food chain with MNPs has appeared as a matter of public concern due to risk of potential health hazard. Brassinosteroid has been shown to play a critical role in alleviating heavy metal stress; however, its function in relieving zinc oxide nanoparticles (ZnO NPs)-induced phytotoxicity remains unknown. In this study, we investigated the potential role of 24-epibrassinolide (BR) in mitigating ZnO NPs-induced toxicity in tomato seedlings. Seedling growth, biomass production, and root activity gradually decreased, but Zn accumulation increased with increasing ZnO NPs concentration (10-100 mg/L) in growth media (½ MS). The augmentation of BR (5 nM) in media significantly ameliorated 50 mg/L ZnO NPs-induced growth inhibition. Visualization of hydrogen peroxide (H2O2), and quantification of H2O2 and malondialdehyde (MDA) in tomato roots confirmed that ZnO NPs induced an oxidative stress. However, combined treatment with BR and ZnO NPs remarkably reduced concentration of H2O2 and MDA as compared with ZnO NPs only treatment, indicating that BR supplementation substantially reduced oxidative stress. Furthermore, the activities of key antioxidant enzymes such as superoxide dismutase (SOD), catalase, ascorbate peroxidase and glutathione reductase were increased by combined treatment of BR and ZnO NPs compared with ZnO NPs only treatment. BR also increased reduced glutathione (GSH), but decreased oxidized glutathione (GSSG)] and thus improved cellular redox homeostasis by increasing GSH:GSSG ratio. The changes in relative transcript abundance of corresponding antioxidant genes such as Cu/Zn SOD, CAT1, GSH1, and GR1 were in accordance with the changes in those antioxidants under different treatments. More importantly, combined application of BR and ZnO NPs significantly decreased Zn content in both shoot and root of tomato seedlings as compared with ZnO NPs alone. Taken together, this study, for the first time, showed that BR could not only improve plant tolerance to ZnO NPs but also reduce the excess zinc content in tomato seedlings. Such a finding may have potential implication in safe vegetable production in the MNPs-polluted areas.

[Study on selenium contents of typical selenium-rich soil in the middle area of Zhejiang and its influencing factors].

Based on the study of typical selenium-rich soil in the middle area of Zhejiang province, the influencing factors of selenium contents were summarized. We found that the selenium contents were controlled by the geological background. It was much higher in Tangxi, Zhijiang, and Jinhua than in other geological background regions. In addition, the contents of selenium in soil under different land use types showed a great difference. The content in the dry land was much more enriched than that in the paddy field. Further research showed that selenium was closely related to soil organic matter because of its adsorption and fixation. Moreover, we found that the soil texture was another important influencing factor. Selenium contents increased with increasing content of clay in the soil.