Genetic and functional characterization of culturable plant-beneficial actinobacteria associated with yam rhizosphere

Actinobacteria were isolated from the rhizosphere of yam plants from agricultural fields from Yeoju, South Korea and analyzed for their genetic and plant‐beneficial functional diversity. A total of 29 highly occurring actinobacterial isolates from the yam rhizosphere were screened for various plant‐beneficial traits such as antimicrobial activity on fungi and bacteria; biocontrol traits such as production of siderophore, protease, chitinase, endo‐cellulase, and β‐glucanase. The isolates were also screened for plant growth‐promoting (PGP) traits such as auxin production, phosphate solubilization, 1‐aminocyclopropane‐1‐carboxylic acid (ACC) deaminase activity, and in vitro Arabidopsis growth promotion. 16S rDNA sequence‐based phylogenetic analysis was carried out on the actinobacterial isolates to determine their genetic relatedness to known actinobacteria. BOX‐PCR analysis revealed high genetic diversity among the isolates. Several isolates were identified to belong to the genus Streptomyces and a few to Kitasatospora. The actinobacterial strains exhibited high diversity in their functionality and were identified as novel and promising candidates for future development into biocontrol and PGP agents.