Bacillus safensis Strain OM1 Mediate Growth Promotion and Meloidogyne incognita Suppression on Potato ( Solanum tuberosum) Plants

Being effective and environmentally safe, biocontrol of root-knot nematodes became a global demand. Bacillus safensis strain OM1 showed nematicidal properties against Meloidogyne incognita increasing J2 mortality (75%) and decreased egg hatching by 78.2% % after 48 h of incubation compared to the control. Greenhouse obtained data showed significant reduction in gall numbers, egg masses and soil population (J2/250 g soil) by 69.8%, 72.99, and 49.39%, respectively. Moreover, M. incognita-infested potato plants inoculated with OM1 showed a significant increase in growth and photosynthetic pigments. Total chlorophyll (1.05 mg/g FW, 88.1%) and carotenoid contents (2.72 mg/g FW, 70.23%) were ameliorated compared to infested plants. Peroxidase (POD) activity of root was significantly reduced after OM1 co-culturing, nevertheless shoot content (18.74 U/mg protein /min) was higher than M. incognita infected plants. B. safensis co-culturing treatment significantly increased polyphenol oxidase (PPO) activities in root and shoot up to 18.73 U/mg protein /min (71.11%) and 32.48 U/mg protein /min (28.2%), respectively compared to M. incognita infested plants. Treatments elevated superoxide dismutase (SOD) activity in both root and shoot, maximizing after B. safensis treatment (0.95 U/mg protein /min) for both. The findings obtained from this work inform the efficiency of B. safensis in potato growth and the amendment of physicochemical characteristics to mitigate M. incognita infection stress.