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Title: Bio-control and plant growth promotion potential of Salicaceae endophytes

item KANDEL, SHYAM - University Of Washington
item FIRRINCIELI, ANDREA - University Of Tuscia
item MUGNOZZA-GIUSEPPE, SCARASCIA - University Of Tuscia
item HARFOUCHE, ANTONIO - University Of Tuscia
item KIM-SOO, HYUNG - University Of Washington
item Okubara, Patricia
item LESTON, NATALIE - Washington State University
item MCGEORGE, KENDRA - Washington State University
item DOTY, SHARON - University Of Washington

Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/10/2016
Publication Date: 3/13/2017
Citation: Kandel, S.L., Firrincieli, A., Mugnozza-Giuseppe, S., Harfouche, A., Kim-Soo, H., Okubara, P.A., Leston, N., Mcgeorge, K., Doty, S.L. 2017. Bio-control and plant growth promotion potential of Salicaceae endophytes. Frontiers in Microbiology. 8:386.

Interpretive Summary: Bacterial endophytes that colonize the roots of plants can serve to control plant pathogens. This manuscripts describes the activity of thirteen endophytes against a number of soilborne fungal pathogens. Our findings indicate several possible mechanisms of control, including production of plant hormones for promoting plant growth, production of antifungal metabolites and production of iron-sequestering compounds.

Technical Abstract: Microbial endophytes are important for growth benefits in a variety of plant species. Microbial communities of the poplar (Populus sp.) and willow (Salix sp.) endosphere have been demonstrated to be important for plant growth promotion, protection from abiotic stresses, and degradation of toxic substances. Our study aimed to investigate anti-fungal activities and plant growth promoting characteristics of selected poplar and willow endophytes. Rhizoctonia solani AG-8, a broad host range fungal pathogen of many food crops, was used to test for anti-fungal activities of the endophytes. Indole-3-acetic acid (IAA), phosphate solubilization, and siderophore producing properties of endophytes were evaluated to assess their potential plan growth promoting abilities. Burkholderia, Rahnella, Pseudomonas, Sphingomonas, Curtobacterium, and Novosphingobium were major endophyte genera that showed anti-fungal activities in in-vitro assays. Burkholderia spp. had relatively stronger anti-fungal effect as compared to the other endophyte strains. Putative genes involved in the synthesis of anti-fungal compounds were observed in the genomes of endophyte strains that showed prominent anti-fungal activities. From the genome analysis of poplar endophytes, Burkholderia spp. (WP40, WP42, and WPB), a 56-kb ofc gene cluster responsible for biosynthesis of a glycolipopeptide named occidiofungin, an anti-fungal compound, was determined. The majority of the endophyte strains having anti-fungal activities produced IAA, solubilized tricalcium phosphate, and synthesized siderophores in the culture medium. These results will guide future molecular studies to decipher the key pathways involved in the improved plant health and growth resulting from the plant microbiome.