Investigation of some germination characteristics, Biochemical traits and expression of antioxidant genes in bread wheat genotypes at seedling stage under mercury metal stress

Heavy metal pollution is one of the most important global causes of soil pollution. Metallic contaminants, even in low concentrations, are carcinogenic due to their non-degradable nature and their physiological effects on living organisms and humans. Seed germination is one of the most important stages in the life cycle plants that respons to environmental factors such as biotic and abiotic stresses. The objective of this experiment was to assess the germination characteristics, biochemical traits and expression of antioxidant genes in bread wheat genotypes at seedling stage under mercury metal stress. The experiment was conducted in split plots based on completely randomized design with three replications in which mercury stress in four levels (including no-application as control and application of 5, 10 and 15 μM mercury chloride) and wheat genotypes in three levels (including Gonbad, Morvarid and N9108 genotypes) were considered as main- and sub-factors, respectively. The results showed that with increasing mercury chloride stress, germination indices as well as morphological and biochemical traits in all three wheat genotypes had a decreasing trend and this decrease in different genotypes was significantly different. Line N9108 had better conditions under mercury metal stress in terms of all measured traits. The expression of superoxide dismutase and peroxidase genes in line N9108 was also higher than the other genotypes, which can indicate the superiority of this line than the other two wheat genotypes under mercury chloride stress conditions.