The Physiological, Biochemical, and Molecular Modifications of Chickpea (Cicer arietinum L.) Seedlings Under Freezing Stress

Fall cultivation of field crops such as chickpea is prone to the risk of freezing stress. It is required to identify the mechanisms through which plants can tolerate low temperatures and provide conditions for fall cultivation of chickpea in the cold regions. To this, an experiment was carried out to evaluate the physiological, biochemical, and molecular alterations of chickpea genotypes (MCC797; cold-tolerant and MCC505; cold-sensitive) under freezing temperatures (- 3, - 6, - 9, and - 12 degrees C). Leaf malondialdehyde (MDA), hydrogen peroxide (H2O2), and electrolyte leakage (EL) were increased due to freezing stress in both genotypes, with a greater increase in the cold-sensitive genotype. The plant survival was decreased 20% at - 12 degrees C in the cold-sensitive genotype, while it remained constant (100%) in the cold-tolerant genotype. The cold-tolerant maximum efficiency of PSII and the PSII operating efficiency recovered faster (24 h after freezing stress; AFS) compare to the cold-sensitive genotype (48 h AFS) during the recovery period. Proline and enzymatic antioxidants activity, including ascorbate peroxidase, catalase (cat), peroxidase (pod), and superoxide dismutase, were increased more rapidly in the cold-tolerant genotype. The relative gene expression of cat, pod, and proline were more stimulated in the cold-tolerant genotype. The cat, pod, and proline were over-expressed on average by 4, 3, and 6 folds, and 16, 13, and 16 folds, in the cold-sensitive and cold-tolerant genotype, respectively, exposed to freezing temperatures. The greater gene expression and the higher antioxidant content of leaves led to lower lipid peroxidation (MDA and H2O2 content) in the cold-tolerant genotype.