Role of Rhizospheric Bacteria in Disease Suppression During Seedling Formation in Millet

Bacteria present in the rhizospheric area of the plant are called rhizospheric bacteria. Rhizospheric bacteria play crucial role in plant development and growth starting from seed germination and also protect the seedlings from fungal phytopathogens. These rhizobacteria are known to produce growth hormones; siderophore; lytic enzymes such as chitinase, lipase, protease, and β-1, 3-glucanase; organic acids; lipopeptides; volatile compounds; and some antibiotics. Some of the common rhizospheric bacteria are Pseudomonas chlororaphis, Bacillus subtilis, Bacillus licheniformis, Pseudomonas fluorescens, Chromobacterium violaceum, Bacillus cereus, and Bacillus stearothermophilus which have been found to suppress the growth of fungal pathogens including Macrophomina phaseolina, Magnaporthe grisea, and Fusarium oxysporum. Lytic enzymes such as chitinase, protease, and β-1, 3- glucanase produced by the rhizobacteria degrade the chitin, glucan, and proteins of the fungal cell wall, respectively. Secondary metabolites produced by the rhizobacteria inhibit the growth of pathogenic fungi by reducing the spore germination, swelling in fungal mycelia, making pore formation in hyphae, cytoplasmic leakages from fungal cells, and finally lysis of hyphae. Pseudomonas and Bacillus are known to induce the induced systemic resistance (ISR) in plants and make them disease resistant against phytopathogens. Millets are group of very important small grain crop which seedling establishment is affected by many soil pathogens. The present chapter is focused on the role of beneficial rhizospheric bacteria in disease suppression in millet crop.