Seed biopriming with Ochrobactrum ciceri mediated defense responses in Zea mays (L.) against Fusarium rot

Seed bio-priming is a simple and friendly technique to improve stress resilience against fungal diseases in plants. An integrated approach of maize seeds biopriming with Ochrobactrum ciceri was applied in Zn-amended soil to observe the response against Fusarium rot disease of Zea mays (L.) caused by Fusarium verticillioides . Initially, the pathogen isolated from the infected corn was identified as F. verticillioides based on morphology and sequences of the internally transcribed spacer region of the ribosomal RNA gene. Re-inoculation of maize seed with the isolated pathogen confirmed the pathogenicity of the fungus on the maize seeds. In vitro, the inhibitory potential of O. ciceri assessed on Zn-amended/un-amended growth medium revealed that antifungal potential of O. ciceri significantly improved in the Zn-amended medium, leading to 88% inhibition in fungal growth. Further assays with different concentrations (25, 50, and 75%) of cell pellet and the cultural filtrate of O. ciceri (with/without the Zn-amendment) showed a dose-dependent inhibitory effect on mycelial growth of the pathogen that also led to discoloration, fragmentation, and complete disintegration of the fungus hyphae and spores at 75% dose. In planta, biopriming of maize seeds with O. ciceri significantly managed disease, improved the growth and biochemical attributes (up to two-fold), and accelerated accumulation of lignin, polyphenols, and starch, especially in the presence of basal Zn. The results indicated that bioprimed seeds along with Zn as the most promising treatment for managing disease and improving plant growth traits through the enhanced accumulation of lignin, polyphenols, and starch, respectively.