Study the biochemical and molecular basis of ISR and plant growth promotion in maize under pathogenic stress condition of Rhizoctonia solani

Abstract

Among the diseases, banded leaf and sheath blight incited by the fungus Rhizoctonia solani Kühn is one of the most widespread diseases of maize. The aim of present study was to evaluation of bioagents for plant growth promoting attributes in maize under pathogenic stress of Rhizoctonia solani. Five bioagents namely Bacillus licheniformis B-02, B. pumilus B-07, B. amyloliquefaciens B-16, B. subtilis B-20 and B. amyloliquefaciens UI were used for evaluation of biochemical and molecular basis of plant growth attributes in maize.  Among them, four strains viz., B. licheniformis B-02, B. pumilus B-07, B. amyloliquefaciens B-16, B. subtilis B-20 showed positive reaction for amylase, HCN, IAA, H2O2, Siderophore, ammonia, chitinase and protease production, starch hydrolysis and phosphate solubilization. Colonization of Bacillus spp. on the root surface and rhizosphere significantly increased total chlorophyll, carbohydrate and protein content were recorded in the plant leaves treated with B. subtilis B-20 and B. amyloliquefaciens B-16 after 30 and 45 days of sowing. The phenylalanine ammonia lyase (PAL) activity proved highest in plants inoculated with B. subtilis B-20. Maximum and uniform lignin deposition in epidermis, vascular bundles and pericycle were observed in the maize plant leaf and sheath inoculated with B. amyloliquefaciens B-16. Increase in the plant growth promotion traits (shoot and root, increase fresh and dry weight of maize seedlings, increase number of nodes, internodes and leaves per plant) was recorded in the plants inoculated with B. licheniformis B-02 as compared to other Bacillus spp. treated plants after 30 and 45 days of sowing.