Methyl Jasmonate and Pseudomonas fluorescens Synergistically Boost Antioxidative Defense, Secondary Metabolites, and Osmolyte Production to Enhance Drought Resilience in Mustard

Drought stress poses a significant threat to crop productivity worldwide, necessitating innovative approaches to mitigate its adverse impact on crops. This study investigates the combined effects of methyl jasmonate and Pseudomonas fluorescens (P. fluorescens) under drought conditions in providing resilience to mustard plants (Brassica juncea) by bolstering antioxidative defense mechanisms, elevating secondary metabolite production, and promoting osmolyte accumulation. Under drought stress, mustard plants exhibited reduced growth and increased oxidative stress markers malondialdehyde and H₂O₂. However, the application of MeJA and P. fluorescens resulted in a substantial improvement in plant growth, as indicated by increased photosynthesis and shoots and root biomass with decrease in oxidative stress. This enhancement was attributed to an upregulation of antioxidative enzymes, including superoxide dismutase, catalase, and ascorbate peroxidase and glutathione reductase which collectively reduced reactive oxygen species levels and prevented oxidative damage. Furthermore, in combination they significantly enhanced the production of secondary metabolites and osmolytes enabling mustard plants to maintain cellular turgor and osmotic balance under drought conditions together with improved stress tolerance. In conclusion, these findings provide valuable insights into sustainable strategies for improving crop resilience to drought, with potential applications in agriculture to mitigate the adverse effects of climate change on crop production.