https://agrinews.es/wp-content/uploads/2014/01/Essential-Oils-as-Modifiers-of-Rumen-Microbial-Fermentation-S.Calsamiglia-2007.pdf

Invited review: Essential oils as modifiers of rumen microbial fermentation.

This review provides a summary of the physiological dynamics andregulation of essential oil production, from the literature and availableinformation on diverse volatile oil crops. Essential oil production is highlyintegrated with the physiology of the whole plant and so depends on themetabolic state and preset developmental differentiation programme of thesynthesising tissue. Essential oil productivity is ecophysiologically andenvironmentally friendly. These and other aspects of the modulation ofessentialoil production are presented, along with a brief outline of the current conceptof the relevant biosynthetic mechanisms.

Regulation of essential oil production in plants

Essential oils are complex mixtures isolated from aromatic plants which may possess antioxidant and anti-inflammatory activities of interest in thye food and cosmetic industries as well as in the human health field. In this work, a review was done on the most recent publications concerning their antioxidant and anti-inflammatory activities. At the same time a survey of the methods generally used for the evaluation of antioxidant activity and some of the mechanisms involved in the anti-inflammatory activities of essential oils are also reported.

/pdf/antioxidant-and-anti-inflammatory-activities-of-essential-36nqpnzt48.pdf

Antioxidant and anti-inflammatory activities of essential oils: a short review.

Nowadays, use of alternative and complementary therapies with mainstream medicine has gained the momentum. Aromatherapy is one of the complementary therapies which use essential oils as the major therapeutic agents to treat several diseases. The essential or volatile oils are extracted from the flowers, barks, stem, leaves, roots, fruits and other parts of the plant by various methods. It came into existence after the scientists deciphered the antiseptic and skin permeability properties of essential oils. Inhalation, local application and baths are the major methods used in aromatherapy that utilize these oils to penetrate the human skin surface with marked aura. Once the oils are in the system, they remodulate themselves and work in a friendly manner at the site of malfunction or at the affected area. This type of therapy utilizes various permutation and combinations to get relief from numerous ailments like depression, indigestion, headache, insomnia, muscular pain, respiratory problems, skin ailments, swollen joints, urine associated complications etc. The essential oils are found to be more beneficial when other aspects of life and diet are given due consideration. This review explores the information available in the literature regarding therapeutic, medical, cosmetic, psychological, olfactory, massage aromatherapy, safety issues and different plants used in aromatherapy. All the available information was compiled from electronic databases such as Academic Journals, Ethnobotany, Google Scholar, PubMed, Science Direct, Web of Science, and library search.

Essential oils used in aromatherapy: A systemic review

Spice and medicinal plants grown under water deficiency conditions reveal much higher concentrations of relevant natural products compared with identical plants of the same species cultivated with an ample water supply. For the first time, experimental data related to this well-known phenomenon have been collected and a putative mechanistic concept considering general plant physiological and biochemical aspects is presented. Water shortage induces drought stress-related metabolic responses and, due to stomatal closure, the uptake of CO2 decreases significantly. As a result, the consumption of reduction equivalents (NADPH + H(+)) for CO2 fixation via the Calvin cycle declines considerably, generating a large oxidative stress and an oversupply of reduction equivalents. As a consequence, metabolic processes are shifted towards biosynthetic activities that consume reduction equivalents. Accordingly, the synthesis of reduced compounds, such as isoprenoids, phenols or alkaloids, is enhanced.

/pdf/stress-enhances-the-synthesis-of-secondary-plant-products-41nmxrct3r.pdf

Stress Enhances the Synthesis of Secondary Plant Products: The Impact of Stress-Related Over-Reduction on the Accumulation of Natural Products

summary
Two lemongrasses. Cymbopogon nardus. (L.) Rendle var. confertiflorus (Steud.) Bor. and Cymbopogon pendulus (Steud.) Wats, were grown under mild and moderate water stress for 45 and 90 d. The impact of in situ drought stress on plants in terms of relative water content, $pS, concentration of proline, activities of PEP carboxylase and geraniol dehydrogenase, and geraniol and citral biogenesis, were investigated. The results revealed that the specific exhibited differential responses under mild and moderate stress treatments. In general, plant growth was reduced considerably whilst the level of essential oils was maintained or enhanced. Significant induction in catalytic activity of PKP carboxylase under water stress was one of the consistent metabolic responses of the aromatic grasses. The major oil constituents., geraniol and citral, increased substantially in both the species. Activity of geraniol dehydrogenase was also modulated under moisture stress. The responses varied depending Upon the level and duration of moisture stress. The observations have been analyzed in terms of possible relevance of some of these responses to their drought stress adaptability tolerance.

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-8137.1994.tb04000.x

Effect of drought stress on growth and essential oil metabolism in lemongrasses

Artemisinin and herbage yield of Artemisia annua plants were determined after application of triacontanol (tria.) and chlormequat (2-chloroethyltrimethylammonium chloride). Tria. at 1.0 and 1.5 mgl−1 produced a statistically significant positive effect on artemisinin level as well as on plant height, leaf and herbage yield. Chlormequat at 1000 and 1500 mgl−1 also increased artemisinin level, decreased the plant height at higher concentrations and increased the leaf and herbage yield at lower concentrations. Tria. application enhanced GA-like activity, but ABA levels decreased, while chlormequat increased ABA but reduced GA-like substances. The effect of Tria. on artemisinin yield seems to be mediated through its effect on plant growth.

Effect of triacontanol and chlormequat on growth, plant hormones and artemisinin yield in Artemisia annua L.

Three major cultivated Mentha spp. (M. arvensis, M. citrata and M. cardiaca) were grown under short-days, normal-days or long-days for 60 cycles. Subsequent to photoperiodic treatment, the plants were assessed for growth behaviour, essential oil content, oil composition and essential oil biosynthesis. The species grew better under long-day conditions. The long-day treatment resulted in flowering in M. citrata, which normally does not flower under our conditions. The oil concentration and biogenesis was maximal in short-day plants. The photoperiodic treatment also affected the oil composition. The observations are discussed in relation to physiology of the oil biogenesis.

A. H. Abad Farooqi

Papers

Regulation of essential oil production in plants

Effect of drought stress on growth and essential oil metabolism in lemongrasses

Effect of triacontanol and chlormequat on growth, plant hormones and artemisinin yield in Artemisia annua L.

Effect of different photoperiodic regimes on growth, flowering and essential oil in Mentha species

Interspecific variation in physiological and metabolic responses of five species of Cymbopogon to water stress