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Plant growth-promoting rhizobacteria (PGPR) are used in agriculture to improve crop yield. Crude smoke-water (made by bubbling plant-derived smoke through water) stimulates germination and improves seedling growth. Some active compounds have been isolated from smoke with karrikinolide (KAR1) stimulating plant growth and trimethylbutenolide (TMB) being inhibitory. These smoke compounds have great potential in agriculture but their interaction with PGPR is unknown. In the present study, a two-factorial pot trial with three replicates per treatment was designed to investigate the interactions between Bacillus licheniformis and two concentrations each of smoke-water, KAR1, and TMB on okra ( Abelmoschus esculentus). Growth and physiological parameters (chlorophyll, carotenoid, protein, sugar and α-amylase) of okra as well as bacterial abundance in the rhizosphere were measured after 5 weeks. Application of B. licheniformis and 10−7 M KAR1 significantly improved the shoot biomass and 10−7 M KAR1 also significantly improved leaf area of okra. However, when 10−7 M KAR1 was applied in combination with B. licheniformis, there was an antagonistic effect on plant growth. While TMB had a negative effect on plant growth, a combination treatment of TMB and B. licheniformis overcame the inhibitory effect of TMB resulting in plant growth similar to the control plants. All treatments had no effect on chlorophyll, carotenoid, protein and sugar concentrations, while α-amylase activity was significantly elevated in okra root treated with 1:500 (v/v) smoke-water. Determining the rhizobacteria populations at harvest showed that all treatments had no significant effect on the rhizosphere microbial abundance. The modes of interaction between PGPR and smoke-derived compounds need to be further elucidated. [ABSTRACT FROM AUTHOR]

In traditional medicine, plant materials are often stored by traditional healers, plant gatherers and traders before they are eventually consumed or sold. The critical point is whether stored medicinal plants are as active as freshly harvested dried material. We evaluated the effects of long-term storage (12 or 16 years) on the antimicrobial (microplate dilution method) and anti-inflammatory (COX-1 and COX-2 inhibition) potencies of 21 extensively used traditional medicinal plants in treating pain and infection-related ailments. The minimum inhibitory concentration (MIC) values obtained against Staphylococcus aureus and Pseudomonas aeruginosa in the stored plant materials were generally either lower or roughly the same as in the fresh material. Most of the stored plant material had comparable minimum microbicidal concentration (MMC) values as the fresh material against S. aureus and P. aeruignosa. Similarly, the majority (71%) of the stored plant material had similar MIC and/or MMC values as fresh material against the fungus Candida albicans. The percentage inhibition of COX-1 by the majority (88%) of the stored material was not significantly different when compared to those freshly collected. Stored material of Clausena anisata, Ekebergia capensis and Trichilia dregeana showed a significantly higher COX-1 inhibition than the fresh material. The therapeutic and conservation implications of the results are discussed. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

AbstractFire is a major environmental selective force that influences plant communities in many parts of the world. Reproductive strategies have evolved as adaptations to the various factors generated by, and/or associated with, fire. This is particularly true for seeds, in which strategies have evolved that respond to both the physical and chemical germination cues that may be associated with fires. Some of these cues are clearly of a primary nature, while others may play a secondary and/or highly specific, or even permissive, role in the germination process. Clearly, there must be considerable interaction between the physical and chemical cues generated by wild fires. Smoke is the most striking chemical factor. Smoke released from burning vegetation contains a chemical signal that triggers germination of both fire climax and non-fire climax species from different parts of the world. It is used in horticulture to stimulate seed germination of wildflower species and can break dormancy and improve germination of vegetable crops, such as lettuce and celery. Smoke can be applied to seeds immediately before sowing, or the seeds may be pretreated and stored until conditions are appropriate for sowing. Both smoke and aqueous smoke-water are active in this respect. The active constituent(s) is volatile, thermostable, water soluble and long-lasting in aqueous solution and in the soil. Attempts to identify the active compound(s) and to determine the mechanism(s) of action have been unsuccessful. Smoke treatment is effective on many seeds that have a light requirement for germination. A very clear concentration effect, resembling that of hormonal responses has been established with aqueous smoke solutions. Smoke extracts interact with gibberellins, cytokinins, abscisic acid and ethylene in photoblastic and in thermodormant seeds. However, despite these interactions it remains questionable whether smoke acts via hormones in stimulating seed germination. There is a clear connection between smoke and life history traits. Smoke may well be the overriding trigger for germination in relation to specific growth habits, regeneration strategies, seed storage, seed sizes, dispersal modes and structures for a large number of species growing in fire-prone habitats. It is becoming increasingly clear that smoke as a germination (or growth regulating) cue must have evolved as part, or as a consequence of fire, as an evolutionary factor. As such, it is probably a very old development and serves as an additional protection mechanism to ensure germination at optimal times for seedling survival. [ABSTRACT FROM AUTHOR]