The alleviation of cadmium toxicity in oilseed rape (Brassica napus) by the application of salicylic acid

Abstract

To assess the potential role of salicylic acid (SA) in plants under cadmium (Cd) stress, a study was conducted on three different oilseed rape (Brassica napus) genotypes. Gas exchange parameters, photosynthetic pigments, antioxidant enzymes activities, mineral nutrients concentration, and ultrastructural analysis were carried out for assessment. Interestingly, cadmium treatment reduced gas exchange parameters, photosynthetic pigments, mineral elements [calcium (Ca), magnesium (Mg), and iron] and the activity of catalase (CAT) enzyme. Whereas, a pronounced increase was observed in malondialdehyde content and antioxidant enzymes, cadmium and zinc accumulation. Impressively, SA played its role as an alleviatory agent by reducing the damage to all parameters caused by Cd except internal CO 2 concentration which was further decreased by SA. Even more, Cd and SA showed synergistic effects by increasing superoxide dismutase, peroxidases, ascorbate peroxidase, guaiacol peroxidase, glutathione reductase and decreasing CAT. Apart from affecting the enzyme activities of oilseed rape, both Cd and SA had the same inhibitory effects on Ca and Mg concentrations. Damage caused by Cd to chloroplast and other internal organelles were almost rectified by SA. Effective role of SA, in alleviating Cd toxicity, could be attributed to the SA-induced improvement of photosynthetic activities, enhancement of antioxidant enzymes activities, reduction in lipid peroxidation and Cd uptake. These findings reflect the possible role of SA as a potential inhibitor of cadmium toxicity by strengthening the internal immunity in oilseed rape.

Role of jasmonic acid in improving tolerance of rapeseed (Brassica napus L.) to Cd toxicity

“…Reduction in heavy metal uptake in response to exogenous application of stress hormones can be attributed to the reduced T r and symplastic loading of Cd into the xylem (Lux et al, 2011). However, a relatively higher T r and reduced Cd translocation into the leaves in JA-treated plants were observed and correspond with our previous findings (Ali et al, 2015), where low Cd accumulation and high T r were observed in rapeseed after SA application. Besides transpiration, metal uptake in the plant can also be influenced by other factors, such as accumulation/exudation of organic compounds such as phenolic compounds.…”

“…These results agree with the findings of Piotrowska et al (2009) which state that JA application significantly inhibits Pb accumulation in W. arrhiza. In addition, other stress hormones, such as salicylic acid (SA), abscisic acid (ABA), and brassinolide (2,4-epibrassinolide), can reduce the uptake of toxic metals (Cd or nickel (Ni)) in hydroponic and soil-grown plants (Kanwar et al, 2012;Ali et al, 2015). Reduction in heavy metal uptake in response to exogenous application of stress hormones can be attributed to the reduced T r and symplastic loading of Cd into the xylem (Lux et al, 2011).…”

“…Previous studies on Cd effects at the subcellular level in plants revealed the chloroplast to be the most sensitive organelle to Cd toxicity (Ali et al, 2015). However, studies on the combined effects of Cd and JA in rapeseed are scarce.…”

“…Approximately 8 kg of ground and sieved soil was loaded into a plastic pot (10 L, 20 cm height) to the brim. The physicochemical properties were the same as in our previous experiment (Ali et al, 2015).…”

Efficiency index as the integral indicator of Triticum aestivum response to growth regulators

“…There are researches comparing several types of PGR that are close to the mode of action (StoynovaBakalova, Petrov, 2010;Choudhary et al, 2011), the effectiveness of several concentrations of the PGR (Gangwar et al, 2011), different exposure times (treatment times) with the PGR (Canakci, Dursun, 2011), the effectiveness of PGR in plants under several types of environmental stress (Fariduddin et al, 2013) or the effectiveness of PGR on several species/genotypes (Ali et al, 2015).…”