Physiological, biochemical, and molecular analysis of PEG-induced water stress responses in lentil (Lens culinaris Medik.)

Lentils are an excellent plant-based protein source, crucial for global food security providing nutritional benefits and economic value, especially in developing countries. BARI Masur-8, a micronutrient-rich lentil variety was exposed to three different concentrations (10%, 20%, and 30%) of polyethylene glycol-6000 (PEG) to investigate the effects of water stress on germination, growth, ion accumulation, different biochemical traits, and expression analysis of antioxidant enzymes. The germination percentage, seedling vigor index, seedling length, fresh and dry weight, relative water content, and pigments of leaves were mostly inhibited with the application of 30% PEG. PEG-induced water stress indicated a strong NO3- accumulation in the root (up to 66%) at 48 h. Furthermore, the K+ and PO43- content resulted in a reduction, and Na+ content enhanced. PEG-mediated water stress also raised the reducing and total sugar content to 72 h. A significant increase in phenolic compounds and proline content was observed in lentil seedlings, where roots showed the highest enhancement. Amino acid content initially increased and then declined in root and stem, whereas protein content showed an opposite trend. The expression analysis of antioxidant enzymes showed a strong expression of the catalase (CAT) gene whereas superoxide dismutase (SOD) and ascorbate peroxidase (APX) showed moderate expression of this gene.