Synergistic interaction of sodium nitroprusside and Serratia marcescens in mitigation of nematode stress in tomato

Plant growth and development are negatively impacted by root-knot nematodes (RKNs), which in turn affects plant production. Chemical nematicides are one of the effective strategies for managing RKNs. But, high concentration of these chemicals is toxic to plants, environment and humans. Therefore, an in-vivo study was conducted to unravel the synergistic interplay sodium nitroprusside (SNP: nitric oxide donor) and, Serratia marcescens in M. incognita-stressed tomato plants. Results revealed that treatment with SNP and bacterial culture cells reduced gall formation and improved morphology. It also reduced nematode-induced oxidative stress in M. incognita-infested tomato plants as compared to untreated plants. Increased photosynthetic parameters including photosynthetic pigments and gas-exchange parameters was also observed in treated plants. Additionally, treated plants exhibited increased antioxidant defense system in terms of upregulated activities of enzymatic antioxidants (Ascorbate peroxidase, guaiacol peroxidase, polyphenol oxidase, catalase, glutathione-S-transferase and superoxide dismutase). Content of non-enzymatic antioxidants (Glutathione, ascorbic acid and tocopherol) was also enhanced in treated plants as compared to untreated nematode-infected plants. Further, treatment with SNP and S. marcescens increased secondary metabolites (total phenol, flavonoid and anthocyanin) and proline content. Reduction in nematode-induced nuclear and membrane damage was also observed in SNP and bacterial culture cells treated tomato plants. The integrative application of SNP and S. marcescens exhibited synergism and overpowered their individual application in reducing the negative effects of nematode stress. The findings of the current investigation suggest the integrative use of SNP and bacteria is more beneficial in alleviating nematode stress in plants.