Background Higher absorption and translocation of sodium (Na) and chlorine (Cl) ions in plant tissue can lead to serious physiological and biochemical changes. However, salicylic acid (SA) is a natural signaling molecule responsible for the induction of environmental stress tolerance in plants. Spraying SA could provide protection against several types of stress such as salinity. This study aimed to show the influence of SA spraying (0.5 and 1 mM) on the damaging effects of NaCl toxicity (150 mM) in Salvia officinalis L. plants. Results The results showed that salinity strongly inhibited the growth of aerial and root parts and this inhibition was accompanied by a significant decrease in the production of chlorophyll pigments (by 63%). There was also a significant accumulation of Na, mainly in the roots. This accumulation of Na+ ions was accompanied by a decrease of calcium (Ca), potassium (K) and phosphorus (P) concentrations. However, SA mainly at 0.5 mM, greatly improved plant growth, essential oils and chlorophyll pigments synthesis. Besides, SA led to a decrease in Na content and an improvement in Ca, K and P content in the leaves and roots. Salt stress decreased the essential oil yield from 1.2% (control) to 0.4% (NaCl). Furthermore, gas chromatography–mass spectrometry analysis of essential oils exhibited that the 1,8-cineol, α-thujone, and camphor were identified as the main components of essential oils under all treatments. However, we noted in stressed plant treated or not with SA the appearance of the new majority compound thujanone. Salt stress decreased the major compounds content. SA spray under stress condition increased the content of major compounds compared to stressed plants untreated with SA. The histological study in scanning electron microscopy showed the peltate glands density decreased strongly under NaCl toxicity. However, SA application on stressed plants increased peltate glands density. On the other hand, the glands of stressed plants often show certain anomalies in the morphology: the first anomaly observed was the presence of glandular structures characterized by deformations in the form of small protuberances located on the head of the gland. The second, a less common abnormality is the morphological change in certain glands that change from a spherical to an ovoid shape. On another hand, all these anomalies were not detected in stressed plants sprayed with SA. Therefore, the absence of these anomalies under the effect of SA showed the repairing effect of this growth regulator. Conclusion The findings of the present work suggest that spraying of SA may be useful for improving the plant growth in NaCl-contaminated areas.

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Background Generally, zinc (Zn) is an essential element and acts as a plant nutrient, but at higher concentrations, it is toxic. Higher uptake and translocation of Zn into plant tissues can cause serious physiological and biochemical alterations. However, salicylic acid (SA) is an endogenous regulator of growth and signaling molecule responsible for inducing environmental stress tolerance in plants. Therefore, spray application of SA could provide protection against several types of stresses such as Zn toxicity. In this context, the ameliorative effect of SA (0.5 and 1 mM) on Salvia officinalis L. under Zn stress (40 mM) was studied. Results Zn stress decreased growth, chlorophyll content, essential oil yield and peltate glandular trichome density. This toxicity can be linked to a strong accumulation of Zn in the various parts of the plant. In addition, Zn stress disturbed nutrients assimilation (K, P and Ca). However, spray of SA, particularly at 0.5 mM improved all parameters studied under both Zn and normal conditions. The positive effects of SA under Zn stress condition may be due to the decrease of Zn accumulation in different parts of the plant. This decrease was accompanied by an increase in K, P and Ca content. In addition, the histological study of S. officinalis leaves showed the presence of two types of glandular hairs, the peltate and capitate glands. In the leaves of stressed plants, we noticed the presence of glands with deformations in the form of pockets in the number of one or more as well as the glands with an oval form. On the other hand, all these abnormalities glands were not detected in stressed plants that were sprayed with SA. Therefore, the absence of these anomalies under the effect of SA showed the remedial effect of this growth regulator. Conclusion The findings of the present work suggest that spraying SA maybe useful for improving the plant growth in Zn-contaminated areas.

Background: Higher absorption and translocation of copper (Cu) in plant tissues can cause serious physiological and biochemical alterations. Salicylic acid (SA) is a signaling molecule responsible for inducing stress tolerance in plants. Therefore, SA spray could provide protection against several types of stress such as Cu toxicity. In this sense, a pot study was conducted to find out whether SA spraying (0.5 and 1 mM) could remedy the Cu (40 mM) toxicity in Mentha suaveolens plants Results: Cooper stress caused a strong accumulation of Cu in the roots with a translocation of this metal to the leaves. Excessive accumulation of this metal decreased Ca, K and p contents. Copper stress also increased H2O2 accumulation and lipid peroxidation. However, SA spraying on these stressed plants decreased Cu concentrations in various parts of the plant. This decrease in Cu contents is accompanied by an increase in K, P and Ca concentrations. SA exerted also a remedial effect on the essential oils performance mainly at 0.5 mM. The histological study of the leaves of the Mentha suaveolens showed the presence of peltate and capitate glands which differ in size, stem and head. Copper decreased glands density but SA spraying increased glands number. Cu caused a variation in essential oils composition. Conclusion: SA at 0.5 mM gives the best quality essential oils of all treatments. This concentration showed the greatest contents of the majority compounds (1,8-cineole, thujanone, camphor and Pulegone).

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