Effects of foliar applications of ascobin on seed protein accumulation in soybean (Glycine max (L.) Merrill) JS 1215 grown under cadmium stress

Abstract

Different natural and anthropogenic activities have contributed to the prevalence of various environmental abiotic stressors that negatively affect agricultural yields worldwide. Also, more adverse impacts can be seen in legumes due to their susceptibility to abiotic stresses compared to cereals. The present study sought to understand cadmium's impact and its alleviation using ascobin on several seed protein properties of soybean (Glycine max). The total seed protein content, estimated using the semi-micro Kjeldahl method, was 36.25% without ascobin (control) at the highest cadmium (Cd) concentration, i.e., 30 mg per kg of soil. The protein content was restored to the highest level (43.75%) with 500 mg/L of ascobin at 10 mg Cd/kg of soil compared to the control without Cd. There was a noticeable decrease in total seed protein content in all sets under control conditions (i.e., without ascobin spray). Also, a negative correlation was found between increasing Cd concentration and the amount of free amino acids, quantified using Lee and Takahashi’s protocol in the seed proteins. The electrophoretic analysis using Gelanalyzer on SDS gels, as per Laemmli’s formulation, revealed that the 7S-Conglycinin protein subfraction was more affected than the 11S-Glycinin subfraction. The analysis revealed how Cd toxicity in soybean plants led to decreased seed protein content and altered proportion of two globulin sub-fractions (glycinin and β-conglycinin). Additionally, it affected the free amino acid content, potentially determining the seeds' nutritional value. However, foliar application of ascobin helped the plants to mitigate these Cd-induced changes and restore the seed quality.