Defatted coagulant seeds of Moringa oleifera and Moringa peregrena mediate alleviation of cadmium toxicity in wheat (Triticum aestivum L.) plant

Abstract

Contaminated soil with toxic heavy metals, particularly cadmium, is an environmental originated challenge from various industrial activities such as effluents and mining and affecting crop growth. Cadmium removal from the soil is a problem, therefore we introduced our approach for reinforcing cadmium tolerance in wheat plant by applying powder (1g/kg soil) of fat-free seeds 'defatted seed or seed-cake' from Moringa oleifera and Moringa peregrena trees before wheat exposure to three levels of soil contamination with cadmium in soil solution (0.5, 1.0 and 1.5 mM) for 35 days. Our data showed that accumulation of Cd in wheat was concentration-dependent and was 4-folds higher in roots than in the shoots. In shoots and roots, cadmium accumulation was 3and 2folds higher at 1.5 mM Cd, respectively. Shoot length and dry mass have reduced by 30 and 58%, respectively. In addition, the photosynthetic pigments have decreased by 50% and the protein profile was altered in leaf. Moringa defatted seeds powder had conferred protection against cadmium toxicity in wheat. Upon defatted seeds pre-treatments, Cd accumulation has diminished by 3 and 2-folds in shoots and roots, respectively and wheat growth and physiological parameters have improved spectacularly. Protein polymorphism and SDS-gel electrophoresis confirmed the appearance of eight newly expressed protein bands in response to Moringa pre-treatments in absence of Cd. Eleven new bands were also expressed under the combined effect of cadmium and Moringa together in wheat leaf and weighed: 261.38, 217.77, 177.38, 135.4, 114.0, 97.0, 74.14, 51.6, 38.2, 24.0 and 13.5 KDa. We believed that the new bands have participated with wheat tolerance. In conclusion, we suggested two strategies: first, Moringa seeds have coagulated cadmium in the soil preventing its absorption and accumulation in wheat plants. Second, wheat newly expressed protein has assisted cadmium detoxification via binding to some peptides, and/or through sequestrating cadmium in the vacuole as metallothioneins and/or polychelatins.