Interaction of 8-Hydroxyquinoline with Soil Environment Mediates Its Ecological Function

Background: Allelopathic functions of plant-released chemicals are often studied through growth bioassays assuming that these chemicals will directly impact plant growth. This overlooks the role of soil factors in mediating allelopathic activities of chemicals, particularly non-volatiles. Here we examined the allelopathic potential of 8-hydroxyquinoline (HQ), a chemical reported to be exuded from the roots of Centaurea diffusa. Methodology/Principal Findings: Growth bioassays and HQ recovery experiments were performed in HQ-treated soils (non-sterile, sterile, organic matter-enriched and glucose-amended) and untreated control soil. Root growth of either Brassica campestris or Phalaris minor was not affected in HQ-treated non-sterile soil. Soil modifications (organic matter and glucose amendments) could not enhance the recovery of HQ in soil, which further supports the observation that HQ is not likely to be an allelopathic compound. Hydroxyquinoline-treated soil had lower values for the CO2 release compared to untreated non-sterile soil. Soil sterilization significantly influenced the organic matter content, PO 4-P and total organic nitrogen levels. Conclusion/Significance: Here, we concluded that evaluation of the effect of a chemical on plant growth is not enough in evaluating the ecological role of a chemical in plant-plant interactions. Interaction of the chemical with soil factors largel

Separation of Allelopathy from Resource Competition Using Rice/Barnyardgrass Mixed-Cultures

Plant-plant interference is the combined effect of allelopathy, resource competition, and many other factors. Separating allelopathy from resource competition is almost impossible in natural systems but it is important to evaluate the relative contribution of each of the two mechanisms on plant interference. Research on allelopathy in natural and cultivated plant communities has been hindered in the absence of a reliable method that can separate allelopathic effect from resource competition. In this paper, the interactions between allelopathic rice accession PI312777, non-allelopathic rice accession Lemont and barnyardgrass were explored respectively by using a target (rice)-neighbor (barnyardgrass) mixed-culture in hydroponic system. The relative competitive intensity (RCI), the relative neighbor effect (RNE) and the competitive ratio (CR) were used to quantify the intensity of competition between each of the two different potentially allelopathic rice accessions and barnyardgrass. Use of hydroponic culture system enabled us to exclude any uncontrolled factors that might operate in the soil and we were able to separate allelopathy from resource competition between each rice accession and barnyardgrass. The RCI and RNE values showed that the plant-plant interaction was positive (facilitation) for PI312777 but that was negative (competition) for Lemont and barnyardgrass in rice/barnyardgrass mixed-cultures. The CR values showed that one PI312777 plant was more competitive than 2 barnyardgrass plants. The allelopathic effects of PI312777 were much more intense than the resource competition in rice/barnyardgrass mixed cultures. The reverse was true for Lemont. These results demonstrate that the allelopathic effect of PI312777 was predominant in rice/barnyardgrass mixed-cultures. The most significant result of our study is the discovery of an experimental design, target-neighbor mixed-culture in combination with competition indices, can successfully separate allelopathic effects from competition

1,8-Cineole Inhibits Both Proliferation and Elongation of BY-2 Cultured Tobacco Cells

Volatile monoterpenes such as 1,8-cineole inhibit the growth of Brassica campestris seedlings in a dose-dependent manner, and the growth-inhibitory effects are more severe for roots than hypocotyls. The preferential inhibition of root growth may be explained if the compounds inhibit cell proliferation more severely than cell elongation because root growth requires both elongation and proliferation of the constituent cells, whereas hypocotyl growth depends exclusively on elongation of existing cells. In order to examine this possibility, BY-2 suspension-cultured tobacco (Nicotiana tabacum) cells were treated with 1,8-cineole, and the inhibitory effects on cell proliferation and on cell elongation were assessed quantitatively. Treatment with 1,8-cineole lowered both the mitotic index and elongation of the cells in a dose-dependent manner, and the half-maximal inhibitory concentration (IC50) for cell elongation was lower than that for cell proliferation. Moreover, 1,8-cineole also inhibited starch synthesis, with IC50 lower than that for cell proliferation. Thus, the inhibitory effects of 1,8-cineole were not specific to cell proliferation; rather, 1,8-cineole seemed inhibitory to a variety of physiological activities when it was in direct contact with target cells. Based on these results, possible mechanisms for the mode of action of 1,8-cineole and for its preferential inhibition on root growth are discussed

Ecological phytochemistry of Cerrado (Brazilian savanna) plants

The Cerrado (the Brazilian savanna) is one of the vegetation formations of great biodiversity in Brazil and it has experienced strong deforestation and fragmentation. The Cerrado must contain at least 12,000 higher plant species.We discuss the ecological relevance of phytochemical studies carried out on plants from the Cerrado, including examples of phytotoxicity, antifungal, insecticidal and antibacterial activities. The results have been classified according to activity and plant family. The most active compounds have been highlighted and other activities are discussed. A large number of complex biochemical interactions occur in this system. However, only a small fraction of the species has been studied from the phytochemical viewpoint to identify the metabolites responsible for these interactions

Does EPA Cause A Decrease in Inflammation of bEnd.3 Cells Through FFAR4?

Atherosclerosis is an inflammatory disease initiated by low and oscillatory shear stress on the endothelium. The inflammatory process recruits leukocytes to the vessel wall by expression of the adhesion molecule VCAM-1. Activation of the NF-κB inflammatory signaling pathway is responsible for the increase in VCM-1 expression. Omega 3 FAs, such as EPA, reduce the risk of atherosclerosis by decreasing this inflammatory response. The pathway by which omega 3 FAs is proposed to inhibit inflammation includes activating FFAR4 to decrease NF-κB activation thereby reducing expression of adhesion molecules. We hypothesized that treatment of endothelial cells with 30 μM EPA would decrease inflammation via activating FFAR4. We evaluated the changes in 2 signaling molecules (IκB and pIKK) and VCAM-1 expression in bEnd.3 cells. Endothelial cells were treated with 30 μM EPA for 24 hours and showed an early decrease in inflammation (0.5 hours; based upon inflammatory signaling molecules) followed by an increase in inflammation after 24 hours. To evaluate if FFAR4 was mediating this response, bEnd.3 cells were treated with 10 μM TUG-891. Treatment with the FFAR4 agonist decreased pIKK at 24 hours suggesting a decrease in the inflammatory response, however, VCAM-1 expression was not changed. The addition of 10 μM of the FFAR4 antagonist AH-7614, increased inflammation (1.5 hours) which was followed by a decrease (24 hours). This response mirrored that of EPA treatment suggesting that AH-7614 is acting as an agonist to FFAR4 (or is affecting inflammation through another pathway). Further experiments are required to understand the role of FFAR4 in mediating the anti-inflammatory response to EPA

The Market Potential for Superconcentrated Apple Juice

Excerpts from the report: The objective of this study was to determine the market potential for superconcentrated fruit juices by (1) investigating the feasibility of commercial introduction of a full-flavor, superconcentrated apple juice, from the point of view of the producer, processor, distributor, and retailer, and (2) measuring consumer acceptance of the new form of apple juice concentrate. The market potential of this high-density (6 to 1) apple juice was studied in Fort Wayne, Ind., from May 9 through July 18, 1960, in a sample of 23 supermarkets. Sales of the apple juice and the 80 other products were audited weekly in 15 of the stores; the remaining 8 stores reported only their total sales of the apple juice at the end of the test period