Evaluation of Gibberellin Synthesis Genes (GA3OX) expression and Antioxidant Capacity in Common Bean (Phaseolus vulgaris L. cv. Sadri) Seeds induced by Chitosan under Salinity

A factorial experiment was conducted based on a completely randomized design with four replications. Treatments included four salinity levels (0, 50, 100 and 150 mM) and four chitosan levels (0, 0.25, 0.50 and 0.75% by weight-volume all of which were dissolved in 1% acetic acid). After RNA extraction and cDNA synthesis, the expression of gibberellin synthesis genes (GA3OX1, GA3OX2, GA3OX3, GA3OX4, GA3OX5 and GA3OX6) was assessed using qRT-PCR, and also some biochemical indicators were measured. The results showed that salinity stress increased the activity of peroxidase and malondialdehyde (MDA) content. Seed pretreatment with chitosan at a concentration of 0.75% increased peroxidase activity and decreased MDA content. Phosphate content in seed pretreatment with 0.75% chitosan and 0 mM salinity levels increased by 57% compared to the control. With increasing salinity, the activity of superoxide dismutase, ascorbate peroxidase and glutathione reductase increased, while catalase activity decreased. The activity of superoxide dismutase in pretreatment with 0.25% chitosan, ascorbate peroxidase and glutathione reductase in pretreatment with 0.75% Chitosan increased at 150 mM salinity stress by 14%, 46% and 34%, respectively. Also, the activity of catalase enzyme in pretreatment with 0.75% chitosan and the level of 0 mM salinity stress increased by 39% compared to the control. GA3OX1 gene expression in priming treatment with 0.75% chitosan at 0 mM salinity level was higher than GA3OX2, GA3OX3, GA3OX4, GA3OX5 and GA3OX6.