Evaluation of Endophytic Bacteria for Plant Growth Promotion and Pathogen Suppression Traits in Saccharum officinarum

Endophytes are beneficial microbes that are capable of promoting growth, besides protecting colonized plants against plant pathogens. These microbes are of either bacterial, fungal or actinomycetes in plants. In the study, the endophytic bacteria isolated from sugarcane with their characterization related to plant growth promotion and pathogen suppression have been reported. Roots, shoots and leaves of rooted tissue culture plantlets of sugarcane cultivars of 87A298 and 2009A107 were excised aseptically and isolated endophytic bacterial strains. The strains were identified using 16S rRNA gene sequence based homology. Molecular characterization of these strains was carried out for presence of antimicrobial genes. The results showed that the endophytes isolated from sugarcane tissue culture plantlets were of the genera Bacillus (B. amyloliquefaciens, B. subtilis, B. cereus, B. safensis, B. siamensis, B. aryabhattai, B. flexus and B. velezensis) and Paenibacillus pabuli. There were three antimicrobial peptides (AMPs) producing genes of bacilysin, bacillomycin and fengycin in B. amyloliquefaciens (SE1, SE7), B. siamensis (SE4, SE16), B. subtilis (SE2, SE3) and B. velezensis (SE15). The biochemical characterization assays showed that some of these strains could produce hydrogen cyanide (HCN), protease, cellulase and indole acetic acid (IAA). Few strains (SE1 and SE4) were phosphate solubilizers, whereas nine isolates were found to be diazotrophs. Most of the bacterial isolates were found antagonistic to Fusarium sacchari, the sugarcane wilt pathogen under in vitro conditions. Overall, the results suggested the scope and potentiality of sugarcane endophytic bacteria, isolated from tissue culture plantlets, in promoting plant growth and suppression of sugarcane pathogen.