Salicylic acid and phenolic compounds under cadmium stress in cucumber plants (Cucumis sativus L.)
2016
Simek, Jiri | Tůma, Jiří | Dohnal, Vlastimil | Musil, Karel | Ducaiová, Zuzana
In this pot experiment, cucumbers (Cucumis sativus L.) were grown in a model soil contaminated by three different concentrations of cadmium (40, 160, and 320 mg.kg⁻¹) with different accompanied anions (Cl⁻, SO₄ ²⁻). In all variants, the most Cd (90 %) was accumulated in the roots, but higher content in the case of Cl⁻. The distribution of Cd in various cucumber organs was as follows: root > stem > leaf > fruits. However, in variants with higher doses of Cd with SO₄ ²⁻, the ratio was changed as follows: root > leaf > stem > fruits. In all variants, least of Cd (max. 1 %) was found in fruits. Variants with the highest Cd doses were significantly different by comparison with all other variants, but higher content was in the case of Cl⁻ anion. Stimulation effect on the biomass production and growth of aerial parts and roots of plants in all variants with Cd was observed. Toxicity symptoms, mainly in the presence of leaf chlorosis and yellowing, were more visible in the variants with Cl⁻, in comparison with SO₄ ²⁻. The amounts of phenol compounds in leaves rose almost in all variants. Only the variants with higher Cd content with SO₄ ²⁻ showed slight reduction. One possible explanation of reduced content may be their bounding on Cd. The content of salicylic acid was reduced in all variants with Cd treatment. However, it is difficult to conclude their role in plant defence responses to heavy metal, because their actual defence mechanism is still unclear. However, from these results, we can suggest that the accompanying anion and the form in which Cd exists may have an impact on the involvement of various antioxidant systems.
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