Effects of heavy metals on seed protein fractions in chickpea, Cicer arietinum (L.)

Worldwide, different abiotic stresses, such as drought, salinity, and heavy metals, harm crop productivity. Legumes, compared to cereals, are more susceptible to these stresses. The current work aimed to provide more insights into the effects of Cd and Pb on various seed protein characteristics of two cultivars of chickpea (Cicer arietinum), HC1 and HC5. At the highest concentrations of Cd, the total seed proteins decreased from 25.2% (control) to 7.1% (30 mg/kg soil), while in the case of the maximum concentration of Pb, 300 mg/kg soil, the protein content decreased to 16.1% from 25.2%. The content of each of the four seed protein fractions viz. albumins, globulins, glutelins and prolamins decreased with an increase in the concentration levels of both heavy metals. The dominating protein fraction, globulins, was reduced by 21.7% in HC1 under Cd stress, while it was reduced by 11.9% in Pb-treated genotype HC5. Electrophoretic analysis of four seed protein fractions on SDS-gels showed only quantitative changes in the polypeptide patterns under varying concentrations of Pb with few qualitative alterations under Cd treatment. The contents of the amino acids tryptophan, cysteine and methionine also decreased with increasing concentrations of heavy metals. Compared to Pb, Cd was found to be more detrimental concerning its influence on seed protein quality. Thus, our analysis revealed how heavy metals impact the quality of chickpea seed proteins by decreasing the content of essential amino acids.