Characterization of endophytic bacteria and their response to plant growth promotion in Helianthus tuberosus L.

The endophytic bacteria isolated from the leaves, stems, tubers and roots of Helianthus tuberosus L. (Jerusalem artichoke) were studied and characterized. The isolated endophytes were clustered by amplified ribosomal DNA restriction analysis (ARDRA) technique and identified by 16 S rRNA sequencing to demonstrate bacteria diversity, mainly in Bacillus, Pseudomonas, Stenotrophomonas, Microbacterium, Curtobacterium. The proportions of endophytes exhibited colonization (from most to least) in stems, leaves, roots and tubers. The more isolates had ACC (1 aminocyclopropane-1-carboxylate) deaminase and nitrogen fixation, the less they showed phosphate and potassium solubilization. Antifungal activity was exhibited only in Bacillus, while many isolates had stress tolerance in polyethylene glycol. Six endophytic bacteria were recolonized into 2 varieties of Jerusalem artichoke (HEL65 and JA102xJA89) and showed increases in height, root and stem weight, and tuber number. The potential local endophyte, Pantoea ananatis 4.14 responded to the tuber by increasing inulin content, which is a valued product of Jerusalem artichoke.