Enhancing Brassica Juncea Growth and Stress Resistance with Plant Growth-Promoting Rhizobacteria Bacillus subtilis (RS-10) Under Cadmium Stress

Pollution by industries and households has also led to increased cadmium (Cd) concentration in agricultural soils thus posing a major risk to plant growth and production. The over use of chemical fertilizers and pesticides further increases environmental degradation. Brassica juncea is a vital oil seed crop, and it is highly vulnerable to cadmium toxicity that interferes with normal physiological and metabolic processes. Rhizobacteria (PGPR) have been shown to promote plant tolerance to stress under such conditions providing a sustainable solution. This research assessed the cadmium-ameliorating effects of Bacillus subtilis RS-10, originally isolated from the rhizosphere of Cynodon dactylon, against cadmium-induced toxicity on Brassica juncea. Plants were subjected to graded levels of CdCl2 (0, 50, 75, and 100 mM), followed by metabolomic characterization through gas chromatography-mass spectrometry (GC-MS). Metabolomic profiling revealed significant modulation of pyruvate metabolism, nitrogen metabolism, the tricarboxylic acid (TCA) cycle, and glutathione metabolism, indicating enhanced energy production and nutrient assimilation. Elevated levels of amino acids, fatty acids, and organic acids further contributed to cadmium tolerance. Overall, B. subtilis RS-10 exhibits strong potential as a sustainable bioinoculant for improving crop performance in Cd-contaminated soils.