Baohong Yu

Cadmium (Cd) is one of the most toxic contaminants, causing a lot of harm to environment and the human health. An outdoor pot experiment for 60 days was conducted to study the Cd(II) effects on growth, biomass, physiological properties, Cd uptake, and accumulation in Youngia japonica plants but also to evaluate the effect of Y. japonica growth on enzyme activity of Cd-contamination soils. Generally, the application of Cd(II) less than 120 mg kg⁻¹ stimulated the growth of the plants, whereas at 160 mg kg⁻¹ or higher levels, a significant reduction was observed. For all treatments > 10 mg kg⁻¹ Cd(II) in soil, values of Cd in roots and aboveground parts were more than the critical value of 100 mg kg⁻¹ and reached highest values of 252.51 and 314.29 mg kg⁻¹, respectively. The bioconcentration factors (BCF) and translation factors (TF) for all Cd treatments were more than 1.0, with the former ranging from 1.03 to 5.46 and the later from 1.04 to 1.33. The activities of peroxidase (POD) and superoxide dismutase (SOD), as well as the levels of glutathione (GSH) and proline in Y. japonica plants after exposure to 10–200 mg kg⁻¹ Cd(II) were stimulated, implying that they were defensive guards to the oxidative stress produced by Cd. The urease, dehydrogenase, and alkaline phosphatase activities under low Cd concentrations can be enhanced by planting Y. japonica species but inhibited under high Cd concentrations. Our data provide comprehensive evidence that Y. japonica has the typical properties of a Cd hyperaccumulator and thus may be practically employed to alleviate Cd from contaminated soils.

Background: The present study involves diversity and biological activities of the endophytic fungal community from Distylium chinense, a rare waterlogging tolerant plant endemic to the Three Gorges Reservoir. This study has been conducted hypothesizing that the microbial communities in the TGR area would contribute to the host plant tolerating a range of abiotic stress such as summer flooding, infertility, drought, salinity and soil erosion etc., and they may produce new metabolites, which may possess plentiful bioactive property, especially antioxidant activity. Therefore in the current study, the antioxidant, antimicrobial and anticancer activities of 154 endophytes recovered from D. chinense have been investigated. Furthermore, the active metabolites of the most broad-spectrum bioactive strain have also been studied. Results: A total of 154 fungal endophytes were isolated from roots and stems. They were categorized into 30 morphotypes based on cultural characteristics and were affiliated with 27 different taxa. Among these, the most abundant fungal orders included Diaporthales (34.4%) and Botryosphaeriales (30.5%), which were predominantly represented by the species Phomopsis sp. (24.7%) and Neofusicoccum parvum (23.4%). Fermentation extracts were evaluated, screening for antioxidant, antimicrobial and anticancer activities. Among the 154 isolates tested, 99 (64.3%) displayed significant antioxidant activity, 153 (99.4%) exhibited inclusive antimicrobial activity against at least one tested microorganism and 27 (17.5%) showed exclusive anticancer activity against one or more cancer cell lines. Specifically, the crude extract of Irpex lacteus DR10–1 exhibited note-worthy bioactivities. Further chemical investigation on DR10–1 strain resulted in the isolation and identification of two known bioactive metabolites, indole-3-carboxylic acid (1) and indole-3-carboxaldehyde (2), indicating their potential roles in plant growth promotion and human medicinal value. Conclusion: These results indicated that diverse endophytic fungal population inhabits D. chinense. One of the fungal isolate DR10–1 (Irpex lacteus) exhibited significant antioxidant, antimicrobial and anticancer potential. Further, its active secondary metabolites 1 and 2 also showed antioxidant, antimicrobial and anticancer potential.