Effects of Arbuscular Mycorrhizal Fungi Glomus mosseae on the Growth and Medicinal Components of Dysosma versipellis Under Copper Stress.

In order to investigate the effects of arbuscular mycorrhizal fungi (AMF) (Glomus mosseae) inoculations and additions of copper (Cu) ion at gradual concentrations (0, 200, and 400 mg kg-1) on different parameters of Dysosma versipellis such as growth, lipid peroxidation (MDA and MRP), antioxidation enzymatic (SOD, POD and CAT) activities, and active medicinal components. Pot experiments have been conducted. The results showed that additions of Cu could inhibit growth and the activity of antioxidant enzymes, increase the degree of membrane lipid peroxidation, and decrease the podophyllotoxin content of D. versipellis compared with the control. Meanwhile, inoculations with AMF enhanced its antioxidant capacity and reduced the degree of membrane lipid peroxidation in leaves of D. versipellis under Cu stress. Besides, AMF inoculations significantly increased the biomass and content of podophyllotoxin in roots of D. versipellis, while it decreased Cu absorption content in roots. Thus, inoculations with AMF could effectively alleviate the Cu stress and improve the active components content of D. versipellis, which might be important for Cu stress adaptation and the improved productivity and quality of D. versipellis.

A Novel Tyrosinase Gene Plays a Potential Role in Modification the Shell Organic Matrix of the Triangle Mussel Hyriopsis cumingii.

Although tyrosinases have been speculated to participate in the shell formation of mollusks, there is still a lack of experimental evidence to support this assumption. In this study, a novel tyrosinase designated HcTyr2 was isolated and characterized from the freshwater mussel Hyriopsis cumingii. The change in HcTyr2 mRNA expression during the process of embryonic development was detected by real-time quantitative PCR. The result showed that the expression of HcTyr2 mRNA was significantly upregulated at the stages of gastrulae and unmatured glochidia (P < 0.05), suggesting that this gene might fundamentally participate in the biogenesis and growth of the initial shell. Meanwhile, the upregulation of HcTyr2 mRNA at the stages of shell regeneration 24 h and 9 days after shell notching in the mantle edge (P < 0.05) implied that it might play an important role in shell periostracum and nacre formation by mediating the cross-linking of quinoproteins to promote the maturity of organic matrix. Additionally, the knockdown of HcTyr2 mRNA by RNA interference resulted in not only the suppression of periostracum growth but also structural disorder of nacre aragonite tablets, as detected by scanning electron microscopy. These results suggested that HcTyr2 might regulate the growth of shell by its oxidative ability to transform soluble matrix proteins into insoluble matrix proteins, then promoting the maturity of the shell organic framework in H. cumingii. In general, our results suggested the importance of HcTyr2 in the shell formation and regeneration of H. cumingii.

Cadmium accumulation in different pakchoi cultivars and screening for pollution-safe cultivars.

The selection and breeding of pollution-safe cultivars (PSCs) is a practicable and cost-effective approach to minimize the influx of heavy metal to the human food chain. In this study, both pot-culture and field experiments were conducted to identify and screen out cadmium pollution-safe cultivars (Cd-PSCs) from 50 pakchoi (Brassica rapa L. ssp. chinensis) cultivars for food safety. When treated with 1.0 or 2.5 mg/kg Cd, most of the pakchoi cultivars (>70%) showed greater or similar shoot biomass when compared with the control. This result indicates that pakchoi has a considerable tolerance to soil Cd stress. Cd concentrations in the shoot varied significantly (P<0.05) between cultivars: in two Cd treatments (1.0 and 2.5 mg/kg), the average values were 0.074 and 0.175 mg/kg fresh weight (FW), respectively. Cd concentrations in the shoots of 14 pakchoi cultivars were lower than 0.05 mg/kg FW. In pot-culture experiments, both enrichment factors (EFs) and translocation factors (TFs) of six pakchoi cultivars were lower than 1.0. The field studies further confirmed that the Hangzhouyoudonger, Aijiaoheiye 333, and Zaoshenghuajing cultivars are Cd-PSCs, and are therefore suitable for growth in low Cd-contaminated soils (≤1.2 mg/kg) without any risk to food safety.

[Differences in cadmium absorption and accumulation of Brassica varieties on cadmium-polluted soil].

A pot experiment was conducted to study the differences in cadmium (Cd) absorption and accumulation of sixty Brassica varieties on the soils added with different concentration of Cd. The results showed that when the soil Cd concentration was 0.6 mg x kg(-1) and 1.2 mg x kg(-1), the percentage of test Brassica varieties whose Cd content exceeded the National Edible Standard was 8.33% and 66.67%, respectively, suggesting that Brassica was easy to be Cd-polluted. The shoot Cd content of all test varieties was below the National Edible Standard, and the biomass of the varieties Changgengbaicai, Shanghaiqing, Aijisuzhouqing, Qingyou 4, Aijiaokuipianheiyebaicai, Zhouyeheiyoudonger, Gaohuaqinggengbaicai, Zaoshenghuajing, Jinguanqingjiangbai, Xiawangqinggengcai, Lifengqinggengbaicai, and Hangzhouyoudonger was not affected. These 12 Brassica varieties could be planted on the soils with light Cd pollution.