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Isolation and diversity of culturable rhizobacteria associated with economically important crops and uncultivated plants in Québec, Canada

Fan, Di, Schwinghamer, Timothy, Smith, Donald L.
Systematic and applied microbiology 2018 v.41 no.6 pp. 629-640
Bacteroidetes, Brassica napus var. napus, Firmicutes, Glycine max, Labrys, Medicago sativa, Microbacterium, Miscanthus, Phalaris arundinacea, Pseudomonas, Stenotrophomonas, Yersinia, Zea mays, alfalfa, bacterial communities, canola, corn, crops, endophytes, growth promotion, plant growth, plant tissues, rhizosphere, rhizosphere bacteria, ribosomal RNA, sequence analysis, soil, soybeans, surveys, Quebec
Plants are chronically associated with microorganisms, residing all tissues. Holonomic analysis of diversity of established rhizobacteria in uncultivated plants is scarce. Thus, the present study was conducted to access the root-associated bacterial diversity of 6 crops (maize, canola, soybean, reed canarygrass, alfafa, and miscanthus) and 20 uncultivated plant species in the region of Sainte-Anne-de-Bellevue, Québec, Canada, using pure-culture methods. Based on 16S rRNA gene sequence analysis, 446 bacterial isolates were distributed onto four phyla (Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes), 32 families and 90 genera. Proteobacteria constituted the largest group of isolates (240), 40% of ectophytic and 61% of endophytic bacteria. Representatives of the genera Bacillus and Pseudomonas dominated in rhizosphere soil; Microbacterium and Pseudomonas were the predominant endophytes. Some genera were associated with specific plant species, such as Stenotrophomonas, Yersinia, Labrys and Luteibacter. Several endophytes were occasionally observed in the rhizosphere, and vice versa. This is the first survey of culturable endophytic bacteria associated with uncultivated plants in Québec. The culturable bacterial community studied herein are assumed to represent a portion of the entire phytomicrobiome of the evaluated plants. Results confirmed that the crops and uncultivated plants of Québec represent an extremely rich reservoir of diverse rhizobacteria.