Effects of high levels of nitrogen and phosphorus on perennial ryegrass (Lolium perenne L.) and its potential in bioremediation of highly eutrophic water.

The conservation and management of rain and water in a city environment are a crucial aspect of sustainability. Sponge cities are a solution for the remediation of excessive water consumption, high pollution, and rainstorm waterlogging in urban areas. Perennial ryegrass (Lolium perenne L.) is a common species and promising bioremediation plant for the construction of sponge cities. It could be useful to purify high nitrogen and phosphorus content in wastewater runoff, but its response to high total nitrogen (TN) and total phosphorus (TP) levels has not been studied. The present study aimed to evaluate the effects of high TN + TP level on seed germination, plant growth, antioxidant response, and assimilation rate of N and P in perennial ryegrass. Compared with the control, treatments with 20 mg/L N + 4 mg/L P (20N4P) significantly decreased germination potential at day 3, but the germination rate at day 10 was similar between all treatments and the control, suggesting that a high TN + TP concentration might delay germination, but not prevent it. Treatment with 20N4P also induced significant withering and decreased shoot length, root length, and dry shoot weight of ryegrass seedlings, compared with the control. Treatments with 80N16P significantly decreased levels of chlorophyll a (Chl-a) and chlorophyll b (Chl-b), demonstrating inhibition of photosynthesis. Compared with the control, treatment with 40N8P increased the carotenoid (Car), malondialdehyde (MDA), and glutathione (GSH) content, which might alleviate oxidative stress induced by high TN + TP concentration. Moreover, high levels of TN + TP (160N32P and 320N64P) significantly reduced the removal capacity of N and P by plants. Overall, the present results provide a theoretical foundation for the development of ryegrass for bioremediation of wastewater during construction of sponge cities.

Growth, physiological and transcriptomic analysis of the perennial ryegrass Lolium perenne in response to saline stress.

Salinization of soil is a global environmental concern. To bioremediate or use saline-alkali lands, most studies focused on screening of halophytes and breeding of saline-tolerant non-halophyte vegetables. Seldom studies investigated effects of salinity on general landscape plants, which are important for landscape construction in urban areas. In the present study, effects of salinity on seed germination and seedling growth of the perennial ryegrass Lolium perenne were investigated. The final seed germination rate was not affected at salinity up to 6.4‰. Partial seedlings wilted in all saline treatments and the mortality of L. perenne was positively correlated with salinity. Treatments with salinity equal to or lower than 1.6‰ did not affect length and dry weight of shoot and root. These results suggested that L. perenne could be sowed and then grow well in low-salinity areas. To explore the underlying physiological mechanisms, contents of photosynthetic pigments and antioxidant indices were determined. The results showed that contents of chlorophyll a, b and carotenoid significantly decreased in all saline treatments, in comparison to the control. Similarly, activities of superoxide dismutase and peroxidase decreased and contents of glutathione and malondialdehyde increased in saline treatments. Additionally, transcriptome analysis identified 792 differentially expressed genes (DEGs) in L. perenne shoots between 6.4‰ saline treatment and the control. Compared with the control, genes in relation to iron transportation and amino acid metabolism were downregulated, but genes participating in energy metabolism were upregulated. These changes would inhibit toxicity of ion accumulation and provide more energy for plants to resist saline stress.

Antitumor and immunomodulatory activity of polysaccharides from the roots of Actinidia eriantha.

AIM OF THE STUDY: The roots of Actinidia eriantha Benth (Actinidiaceae) have been used for cancers in the Chinese folk medicine. The present study aimed at evaluating the antitumor potentials of the polysaccharides from the roots of Actinidia eriantha and elucidating their immunological mechanisms by determining the effects on the growth of tumor transplanted in mice and the immune response in tumor-bearing mice. MATERIALS AND METHODS: The total polysaccharide AEP and fours purified polysaccharides AEPA, AEPB, AEPC and AEPD were isolated and purified from the roots of Actinidia eriantha by hot water extraction, ethanol precipitation, dialysis and gel filtration. Their effects on the growth of mouse transplantable tumor, splenocyte proliferation, the activity of natural killer (NK) cells and cytotoxic T lymphocytes (CTL), production of cytokines from splenocytes, and serum antigen-specific antibody levels in tumor-bearing mice were measured. RESULTS: AEP and four purified polysaccharides could not only significantly inhibit the growth of mouse transplantable tumor, but also remarkably promote splenocytes proliferation, NK cell and CTL activity, IL-2 and IFN-gamma production from splenocytes, and serum antigen-specific antibody levels in tumor-bearing mice. CONCLUSIONS: The antitumor activity of AEP and four purified polysaccharides might be achieved by improving immune response, and the composition of the monosaccharides, uronic acid contents and molecular weight could affect their antitumor and immunomodulatory activity.

Novel polysaccharide adjuvant from the roots of Actinidia eriantha with dual Th1 and Th2 potentiating activity.

The plant polysaccharides are recognized as an effective biological response modifier with low toxicity. In this study, the water-soluble polysaccharide from the roots of Actinidia eriantha (AEPS) was evaluated for its toxicity and adjuvant potential on the specific cellular and humoral immune responses to ovalbumin (OVA) in mice. AEP did not cause any mortality and side effects when mice were administered subcutaneously twice at the dose up to 5.0mg at intervals of 7 days. The mice were immunized subcutaneously with OVA 100 microg alone or with OVA 100 microg dissolved in saline containing Quil A (10 microg) or AEPS (25, 50, or 100 microg) on days 1 and 15. Two weeks later, splenocyte proliferation, natural killer (NK) cell activity, production and mRNA expression of cytokines from splenocytes, and serum OVA-specific antibody titers were measured. The Con A-, LPS-, and OVA-induced splenocyte proliferation and the serum OVA-specific IgG, IgG1, IgG2a, and IgG2b antibody titers in the immunized mice were significantly enhanced by AEPS (P<0.05, P<0.01 or P<0.001). AEPS also significantly promoted the production of Th1 (IL-2 and IFN-gamma) and Th2 (IL-10) cytokines and up-regulated the mRNA expression of IL-2, IFN-gamma, IL-4 and IL-10 cytokines and T-bet and GATA-3 transcription factors in splenocytes from the immunized mice (P<0.05, P<0.01 or P<0.001). Besides, AEPS remarkably increased the killing activities of NK cells from splenocytes in the immunized mice (P<0.01 or P<0.001). The results indicated that AEPS had strong potential to increase both cellular and humoral immune responses and elicit a balanced Th1/Th2 response, and that AEPS may be a safe and efficacious adjuvant candidate suitable for a wide spectrum of prophylactic and therapeutic vaccines.