Effect of clone selection, nitrogen supply, leaf damage and mycorrhizal fungi on stilbene and emodin production in knotweed.

BACKGROUND: Fallopia japonica and its hybrid, F. xbohemica, due to their fast spread, are famous as nature threats rather than blessings. Their fast growth rate, height, coverage, efficient nutrient translocation between tillers and organs and high phenolic production, may be perceived either as dangerous or beneficial features that bring about the elimination of native species or a life-supporting source. To the best of our knowledge, there have not been any studies aimed at increasing the targeted production of medically desired compounds by these remarkable plants. We designed a two-year pot experiment to determine the extent to which stilbene (resveratrol, piceatannol, resveratrolosid, piceid and astringins) and emodin contents of F. japonica, F. sachalinensis and two selected F. xbohemica clones are affected by soil nitrogen (N) supply, leaf damage and mycorrhizal inoculation. RESULTS: 1) Knotweeds are able to grow on substrates with extremely low nitrogen content and have a high efficiency of N translocation. The fast-spreading hybrid clones store less N in their rhizomes than the parental species. 2) The highest concentrations of stilbenes were found in the belowground biomass of F. japonica. However, because of the high belowground biomass of one clone of F. xbohemica, this hybrid produced more stilbenes per plant than F. japonica. 3) Leaf damage increased the resveratrol and emodin contents in the belowground biomass of the non-inoculated knotweed plants. 4) Although knotweed is supposed to be a non-mycorrhizal species, its roots are able to host the fungi. Inoculation with mycorrhizal fungi resulted in up to 2% root colonisation. 5) Both leaf damage and inoculation with mycorrhizal fungi elicited an increase of the piceid (resveratrol-glucoside) content in the belowground biomass of F. japonica. However, the mycorrhizal fungi only elicited this response in the absence of leaf damage. Because the leaf damage suppressed the effect of the root fungi, the effect of leaf damage prevailed over the effect of the mycorrhizal fungi on the piceid content in the belowground biomass. CONCLUSIONS: Two widely spread knotweed species, F. japonica and F. xbohemica, are promising sources of compounds that may have a positive impact on human health. The content of some of the target compounds in the plant tissues can be significantly altered by the cultivation conditions including stress imposed on the plants, inoculation with mycorrhizal fungi and selection of the appropriate plant clone.

Factors influencing the production of stilbenes by the knotweed, Reynoutria x bohemica.

BACKGROUND: Japanese knotweed, Reynoutria japonica, is known for its high growth rate, even on adverse substrates, and for containing organic substances that are beneficial to human health. Its hybrid, Reynoutria x bohemica, was described in the Czech Republic in 1983 and has been widespread ever since. We examined whether Reynoutria x bohemica as a medicinal plant providing stilbenes and emodin, can be cultivated in spoil bank substrates and hence in the coalmine spoil banks changed into arable fields. We designed a pot experiment and a field experiment to assess the effects of various factors on the growth efficiency of Reynoutria x bohemica on clayish substrates and on the production of stilbenes and emodin in this plant. RESULTS: In the pot experiment, plants were grown on different substrates that varied in organic matter and nutrient content, namely the content of nitrogen and phosphorus. Nitrogen was also introduced into the substrates by melilot, a leguminous plant with nitrogen-fixing rhizobia. Melilot served as a donor of mycorrhizal fungi to knotweed, which did not form any mycorrhiza when grown alone. As expected, the production of knotweed biomass was highest on high-nutrient substrates, namely compost. However, the concentration of the organic constituents studied was higher in plants grown on clayish low-nutrient substrates in the presence of melilot. The content of resveratrol including that of its derivatives, resveratrolosid, piceatannol, piceid and astringin, was significantly higher in the presence of melilot on clay, loess and clayCS. Nitrogen supplied to knotweed by melilot was correlated with the ratio of resveratrol to resveratrol glucosides, indicating that knotweed bestowed some of its glucose production upon covering part of the energy demanded for nitrogen fixation by melilot's rhizobia, and that there is an exchange of organic substances between these two plant species. The three-year field experiment confirmed the ability of Reynoutria x bohemica to grow on vast coalmine spoil banks. The production of this species reached 2.6 t of dry mass per hectare. CONCLUSIONS: Relationships between nitrogen, phosphorus, emodin, and belowground knotweed biomass belong to the most interesting results of this study. Compared with melilot absence, its presence increased the number of significant relationships by introducing those of resveratrol and its derivatives, and phosphorus and nitrogen. Knotweed phosphorus was predominantly taken up from the substrate and was negatively correlated with the content of resveratrol and resveratrol derivatives, while knotweed nitrogen was mainly supplied by melilot rhizobia and was positively correlated with the content of resveratrol and resveratrol derivatives.

Self-reported compliance with osteoporosis medication-qualitative aspects and correlates.

OBJECTIVES: The analysis aims to assess (1) compliance with anti-osteoporosis pharmacotherapy and (2) the prevalence of calcium and vitamin D co-medication among Czech women in common clinical practice. METHODS: A cross-sectional multicentre questionnaire survey was performed in consecutive secondary care female patients aged > or =40 years. Three main dimensions of compliance were studied: drug compliance (based on missed doses over the last month), co-medication with calcium/vitamin D and compliance with dosing instructions for safe and effective use of bisphosphonates (BIS). RESULTS: The therapy in 200 osteoporosis patients was alendronate (44.5%), risedronate (24.5%), raloxifene (18%) and calcitonin (13%). The three dimensions of compliance were not associated with each other. None of the compliance-related outcomes correlated with the osteoporosis knowledge score obtained in the Osteoporosis Questionnaire (OPQ) of Pande et al. The most frequently reported reason for non-compliance was "drug not handy". Similar mean compliance rates were achieved with once daily and once weekly BIS. The rates of current calcium and vitamin D co-medication were 73% and 62%, respectively. Calcium co-medication was associated with obtaining information on medications against osteoporosis from other sources besides health care professionals (P = 0.038). Compliance with dosing instructions correlated negatively with age (P = 0.001). CONCLUSION: Compliance with osteoporosis medication in Czech women is suboptimal, in particular the prevalence of co-medication with calcium/vitamin D should be higher. It is needed to implement strategies focused on the patient's beliefs about the disease and perceptions of outcome rather than those promoting the knowledge alone.