Synergistic effects of salicylic acid and magnesium oxide nanoparticles on cold stress and miRNA expression in alfalfa (Medicago sativa L.) genotypes

This study aimed to investigate the responses of alfalfa (Medicago sativa L.) genotypes (Van/Denizli) to cold stress and to evaluate the effects of exogenous salicylic acid (SA), magnesium oxide nanoparticles (MgO NPs) and their combination (SA+MgO NPs) on these responses. Alfalfa genotypes were subjected to treatments with SA (1 and 2 mM), MgO NPs (5 and 20 ppm), and SA + MgO NPs, followed by exposure to cold stress at 10 degrees C and 4 degrees C for 14 days each. Changes in biochemical parameters, scanning electron microscope (SEM) image analysis, and alterations in miRNA (miRNA156 and miRNA173) gene expression levels were examined to assess the mitigating effects of the treatments on cold-induced damage. The results indicate that under cold conditions, SA and MgO NPs singularly reduced lipid peroxidation (LPO) and hydrogen peroxide (H2O2) contents while increasing proline content. The combination of 2 mM SA+20 ppm MgO NPs exhibited the most significant alleviating effects against cold stress. Analysis of miRNA gene expression levels revealed differential regulation patterns, with miR156 and miR173 showing distinct responses to temperature and treatment combinations. Our study underscores the potential of MgO NPs and SA as promising agents to enhance cold tolerance and mitigate crop losses in agriculture. Future research endeavors exploring the efficacy of these substances across diverse plant genotypes under cold stress conditions could offer valuable insights into developing strategies for enhancing cold stress resilience and improving agricultural productivity.