Plant secondary metabolites (SMs) are not only a useful array of natural products but also an important part of plant defense system against pathogenic attacks and environmental stresses. With remarkable biological activities, plant SMs are increasingly used as medicine ingredients and food additives for therapeutic, aromatic and culinary purposes. Various genetic, ontogenic, morphogenetic and environmental factors can influence the biosynthesis and accumulation of SMs. According to the literature reports, for example, SMs accumulation is strongly dependent on a variety of environmental factors such as light, temperature, soil water, soil fertility and salinity, and for most plants, a change in an individual factor may alter the content of SMs even if other factors remain constant. Here, we review with emphasis how each of single factors to affect the accumulation of plant secondary metabolites, and conduct a comparative analysis of relevant natural products in the stressed and unstressed plants. Expectantly, this documentary review will outline a general picture of environmental factors responsible for fluctuation in plant SMs, provide a practical way to obtain consistent quality and high quantity of bioactive compounds in vegetation, and present some suggestions for future research and development.

Response of Plant Secondary Metabolites to Environmental Factors.

Antioxidant activities of the essential oils and methanol extracts from myrtle (Myrtus communis var. italica L.) leaf, stem and flower

Stressed food – The impact of abiotic environmental stresses on crop quality

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.

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

Influencing the product quality by deliberately applying drought stress during the cultivation of medicinal plants

Water deficit effects on Salvia officinalis fatty acids and essential oils composition

Effect of harvesting time on phenolic compounds and antiradical scavenging activity of Borago officinalis seed extracts

The essential oils obtained from leaves of two Myrtus communis varieties (baetica and italica), growing wild in North Tunisia, were investigated by GC and GC–MS at their different phenological stages. The highest essential oil yield was observed at the flowering stage with 0.6% (w/w) for italica and 0.4% (w/w) for baetica and 49 compounds were identified. The main essential oil leaf compounds of both myrtle varieties, belonging to the monoterpene class, were α-pinene, 1,8-cineole, limonene and linalool and their percentages showed significant changes during the phenological stages.

GC Comparative Analysis of Leaf Essential Oils from Two Myrtle Varieties at Different Phenological Stages

Effect of cutting date and position on rooting ability and fatty acid composition of Carignan (Vitis vinifera L.) shoot

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W. Aidi Wannes

Papers

Water deficit effects on Salvia officinalis fatty acids and essential oils composition

Effect of harvesting time on phenolic compounds and antiradical scavenging activity of Borago officinalis seed extracts

GC Comparative Analysis of Leaf Essential Oils from Two Myrtle Varieties at Different Phenological Stages

Effect of cutting date and position on rooting ability and fatty acid composition of Carignan (Vitis vinifera L.) shoot

Borago Officinalis L. Foliar Fatty Acids