Eco-Friendly Biocontrol through Seed Biopriming and Induced Systemic Resistance against Maydis Leaf Blight of Maize Caused by Bipolaris maydis

Abstract

Though chemical seed treatment is usual and affluent, using the prevailing beneficial microorganisms in nature eases the detrimental effect of chemicals on nature and also human beings in many possible ways. This study highlights the biocontrol potential of seed biopriming as an eco-friendly alternative to chemical seed treatments for managing Maydis leaf blight caused by Bipolaris maydis. So, seed biopriming is preferable which is a biological seed treatment and involves seed hydration followed by inoculation with useful microorganisms which adds improvement to seeds in terms of viability, vigor indices and germination. Induced systemic resistance (ISR) is a resistance mechanism in plants that is activated by infection with biological agents. In the present study two fungal and two bacterial biocontrol agents used individually and also in combination along with pathogen and control and maximum seed vigour index was found in P. fluorescens + B. subtilis (3644.04). Host defense responses were activated through induced systemic resistance and observed that antioxidant enzymes were higher in P. fluorescens + B. subtilis and T. harzianum colonized seedlings. Total phenols and polyphenol oxidases were higher after 3rd day of pathogen inoculation whereas, peroxidase and phenylalanine ammonia lyase were higher after 5th day of pathogen inoculation and superoxide dismutase was activated in transient manner. This clearly depicts that bio-priming enhances the seed vigour, antioxidant  enzymes production and accumulation which helps in overcoming the biotic stress tolerance  by reducing the infection process of the pathogen during the plant growth through inducing systemic resistance.  Induced systemic resistance (ISR) mediated by biocontrol agents was due to the upregulation of defense related enzymes and by the accumulation of phenolic compounds.