Anti-fungal and plant growth-promoting characteristics of three poplar endophytic Burkholderia. 
S. KANDEL (1), A. Firrincieli (2), S. Doty (1) (1) School of Environmental and Forest Sciences, University of Washington, U.S.A.; (2) Department for Innovation Biological, Agro-Food and Forest System, University of Tuscia, Italy

Microbial communities of the poplar (Populus 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 three poplar endophytic Burkholderia strains; WP40, WP42, and WPB. Rhizoctonia solani AG-8, a broad host range fungal pathogen of many food crops, was used to test for anti-fungal activities of these endophyte strains. In addition, indole-3-acetic acid, phosphate solubilization, and siderophore producing properties of the Burkholderia strains were evaluated to assess their potential plant growth promoting abilities. All three Burkholderia strains showed very strong anti-fungal effects in-vitro. Putative genes involved in the synthesis of anti-fungal compounds were observed in the genomes of all three B. strains. A 56-kb ofc gene cluster responsible for biosynthesis of the anti-fungal glycolipopeptide, occidiofungin, was present in the genomes of WP40, WP42, and WPB. All three strains produced IAA, solubilized tricalcium phosphate, and synthesized siderophores in the culture medium. Additionally, comparative genomics was used to distinguish the secretion systems and extracellular features of poplar Burkholderia strains from known pathogenic B. strains. Key pathogenesis-related components of the Type III and Type VI secretion systems were absent from the genomes of WP40, WP42, and WPB in contrast to pathogenic B. strains, suggesting that the secretion systems of poplar B. strains are deficient to initiate infection, and are thus separate from pathogenic B. strains. Poplar B. strains can promote plant growth possibly through the mechanisms of IAA production, nutrient acquisition, and protection from fungal diseases without posing the risk of pathogenicity. 

Abstract Number: P4-96
Session Type: Poster