Effective Utilization of Vaccinium virgatum Aiton Stems as Functional Materials: Major Constituent Analysis and Bioactivity Evaluation

Seasonal variation of antioxidant bioactive compounds in southern highbush blueberry leaves and non-destructive quality prediction in situ by a portable near-infrared spectrometer

Blueberry leaves (BBL) are a natural source with strong antioxidant activity, but bioactive compounds and their seasonal variation remain vague. Here, two major classes of compounds including four caffeoylquinic acids and eight flavonoids were identified in two southern highbush cultivars ("Lanmei" #1 and "Jewel") grown in China. Major bioactive compounds were discovered using an online HPLC post-column derivatization system and determined as neochlorogenic acid (NeoCA), chlorogenic acid (CA), rutin, hyperoside, and isoquercitrin. CA contributed the most to the BBL antioxidant activity. "Lanmei" showed significant advantages in terms of rutin content and antioxidant activity over "Jewel" (P < 0.05). The highest CA content (CAC) of juvenile "Jewel" leaves reached 17.9%. July was the optimum harvest time for both cultivars after fruiting stage. Total phenolic content (TPC) and Trolox equivalent antioxidant capacity (TEAC) of fresh BBL were accurately predicted by a portable near-infrared (NIR) device in a rapid, low-cost, and non-destructive way in situ.

Study on the migration behaviour of heavy metals at the improved mine soil-plant rhizosphere interface

With the increasing shortage of land resources and the aggravation of soil pollution in mining areas, the remediation of soil in abandoned mining areas has gradually attracted people's attention. The remediation of heavy metal contaminated soil in mining areas is the key to reduce the harm of heavy metals to the environment and human health. In this study, municipal sludge and phytoremediation technology were combined to investigate the migration and transformation of heavy metals at the soil-plant interface in improved mining areas through indoor pot experiments. The results showed that heavy metals in non-rhizosphere soil entered the rhizosphere environment with the growth of plants, leading to the increase of heavy metal content in rhizosphere soil. The cumulative amounts of Cu, Zn, Pb and Cd were 1299.32, 832.10, 347.89 and 71.34 mg/kg, respectively. The content of oxidized Cu and Zn decreased with increasing planting days, while the oxidized Pb and Cd showed an increasing trend. Under acidic conditions, H+ is easy to compete with heavy metal ions for exchangeable positions in the clay mineral layer, so that the reducible heavy metals are easy to be converted into exchangeable states. In this paper, the effects of various factors on the distribution of heavy metals were discussed by adjusting soil pH, adding humic acid and root exudates, so as to analyse the migration and transformation mechanism of heavy metals at the soil-plant interface, and provide a reliable theoretical basis for soil remediation in mining areas.

Application potential of Vaccinium ashei R. for cadmium migration retention in the mining area soil

Despite numerous reports on phytoremediation of heavy metals contaminated soil, there are few reports on plant retention of heavy metals in the mining area slope. This study was the first of its kind to explore the cadmium (Cd) retention capacity of the blueberry (Vaccinium ashei Reade). Firstly, we investigated the stress response of blueberry to different soil Cd concentrations (1, 5, 10, 15, 20 mg/kg) to assess its potential for phytoremediation by pot experiments. The results showed that the blueberry biomass exposed to 10 and 15 mg/kg Cd was significantly increased compared with the control (1 mg/kg Cd); the blueberry crown increased by 0.40% and 0.34% in 10 and 15 mg/kg Cd-contaminated soil, respectively, compared with control; the blueberry heigh did not even change significantly in each treatment group; the total chlorophyll content, peroxidase and catalase activity of blueberry were enhanced in 5-20 mg/kg Cd treatments. Furthermore, the Cd contents of blueberry in the root, stem and leaf increased significantly as the Cd concentration of soil increased. We found that more Cd accumulated in blueberry root: the bioaccumulation concentration factor was root > stem > leaf for all groups; the residual-Cd (Cd speciation) in soil increased by 3.83%-411.11% in blueberry-planted versus unplanted groups; blueberry improved the Cd-contaminated soil micro-ecological environment including soil organic matter, available K and P, as well as microbial communities. Then, to investigate the effect of blueberry cultivation on Cd migration, we developed a bioretention model and revealed that soil Cd transport along the model slope was significantly weakened by blueberry cultivation, especially at the bottom of the model. In a word, this research suggests a promising method for the phytoremediation of Cd-contaminated soil and the reduction of Cd migration in mining areas.

Prediction of the Adult T-Cell Leukemia Inhibitory Activity of Blueberry Leaves/Stems Using Direct-Injection Electron Ionization-Mass Spectrometry Metabolomics

Although Vaccinium virgatum Aiton leaves and stems inhibit adult T-cell leukemia (ATL) cells, leaves and stems can differ between individual plants and by time and location. In this study, leaf and stem components were profiled in the same individual plant using direct-injection electron ionization-mass spectrometry (DI-EI-MS) metabolomics, with the aims of analyzing the anti-ATL activity, and quantifying proanthocyanidins (PACs). Leaves, stems, and leaf/stem mixtures showed distinct and characteristic spectra. Anti-ATL activity was stronger in stems than leaves, and the PAC content was higher in stems than leaves. These data were subjected to bivariate analysis to identify the factor (m/z) responsible for the inhibitory effect of ATL based on the highest coefficient of determination (R2). The results of this DI-EI-MS metabolomics analysis suggest that among PACs contained in V. virgatum stems and leaves, the fragment ion at m/z 149 contributes significantly to anti-ATL activity.