Mung Bean Genotypes Demonstrate a Correlative Response at Biochemical and Molecular Level Under Salinity Stress

Salt stress is one of the main environmental factors inhibiting the growth of plants because it adversely disturbs the balance between reactive oxygen species content and antioxidant defense, causing oxidative stress. In this research, the effect of salt stress at different concentrations of NaCl (3, 6, 9 dS m⁻¹) was investigated on 5 mung bean genotypes (9, 1015, 1018, 1021 and Gohar), specifically for antioxidant activity and proline content. In this regard, the relative expression of key genes involved in proline synthesis (P5 CS, P5CR) and degradation (PDH) were also studied in the leaves of tolerant genotype (1015) and susceptible genotype (9) by qRT-PCR under only 9 dS m⁻¹ NaCl. Given the results, the activity of antioxidant enzymes, including ascorbate peroxidase, catalase, and guaiacol peroxidase significantly were increased particularly in genotype 1015 under 9 dS m⁻¹ NaCl. Salinity stress led the elevation of proline contents. As a result, proline accumulation increased due to P5 CS, P5CR upregulation, and PDH down-regulation. On the other hand, incrementing proline in tolerant genotype (1015) versus susceptible genotype (9) implicates the key role of proline in salinity stress withstanding. Conclusively, the study results could be efficiently applicable in advance plant breeding programs.