Characterization of actinobacteria from wheat seeds for plant growth promoting traits and protection against fungal pathogens

Seeds harbor naturally occurring microbial endophytes that proliferate during seedling development; playing crucial roles in seedling growth, establishment, and protection against fungal pathogens. Resilient actinobacteria of wheat seeds have been explored in this study for their beneficial traits. Ten actinobacteria isolated from the surface-sterilized seeds of wheat variety HD3117 were identified as nine species of Streptomyces and one of Nocardiopsis. Most isolates could grow at 42 degrees C, 5% NaCl, and 10% poly ethylene glycol (PEG); exhibited variable hydrolytic enzyme production for amylase, cellulase, and protease. Few isolates produced indole acetic acid (9.0-18.9 mu g ml(-1)) and could solubilize P (11.3-85.2 mu g ml(-1)). The isolates were antagonistic against one or more fungal pathogens under test (Fusarium graminearum, Bipolaris sorokiniana, Alternaria sp., and Tilletia indica), of which Streptomyces sampsonii WSA20 inhibited all in dual culture assay. Priming of wheat seeds with the efficient isolate WSA20 led to effective colonization in the root zone and significantly improved germination, shoot and root length in seed germination assay. Significant protection was recorded in microcosm experiment where no symptoms of disease were observed. This study shows the significance of actinobacterial endophytes of wheat seeds in influencing seed germination and seedling growth while protecting from soil-borne pathogens. It is original and suggests that the seed inhabiting efficient actinobacteria may be developed as efficient bioinoculant for sustainable farming system.