Phosphorus solubilizing Priestia Megaterium AIOASP1 enhances tomato growth and wilt resistance through antioxidant...

The present study demonstrated the beneficial effects of phosphate-solubilizing Priestia megaterium AIOASP1 from Curcuma longa on insoluble phosphate solubilization, plant growth promotion, and Fusarium wilt disease management in tomato plants. The strain AIOASP1 exhibited significant phosphate-solubilizing ability (23.91-85.78 mg L^-1) of phosphate), further confirming the production of organic acids through GC-MS metabolomics. Amplification of gcd (PQ352459) and pqq (PQ352460) genes involved in phosphate solubilization was also performed. This strain exhibited growth-promoting traits including IAA, ACC deaminase, siderophore, ammonia, HCN, and EPS production. The strain AIOASP1 inhibited ∼73 % of Fusarium oxysporum f. sp. lycopersici mycelial growth, resulting in structural abnormalities visualized via SEM. Pot trials indicated seed priming with AIOASP1 increased soil phosphorus availability 1.86-fold and phosphorus uptake by plants. It reduced disease severity and improved the germination rate, vigor index, and overall plant growth, including total chlorophyll, carotenoids, and Osmoprotectants in Fusarium-stressed plants. Histochemical assays confirmed reduced oxidative stress at lower O₂^.-, H₂O₂ and MDA levels in leaves of AIOASP1-treated plants. Moreover, the fluorescence probes DHE and DCF-DA confirmed the reduction in ROS in the roots of pre-inoculated tomato plants under Fusarium-challenged conditions. AIOASP1 treatment enhanced the phenolic content and antioxidant enzyme activities and upregulated the expression of stress response genes (SOD, CAT, PPO, APx, GR), pathogenesis-related protein (CHI), cell wall synthesis (GLU), and the phenylpropanoid pathway (PAL) in Fusarium-infected plants.