Isolation Of Rhizobacteria In Southwestern Quebec Canada

Download or read book Isolation of Rhizobacteria in Southwestern Québec, Canada written by Di Fan and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Wild plants, especially those grown on impoverished land, have been shown to host a great diversity of bacterial species. Since there is no holonomic analysis of the diversity of the established rhizobacteria for crops and wild plants of Southwestern Québec, Canada, the first goal of this project was to determine the culturable rhizobacterial communities associated with a selected set of crops and wild plants in the region of Sainte-Anne-de-Bellevue, Québec. A total of 446 rhizobacterial strains were isolated, which were classified into 90 bacterial genera, with Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes as the dominant phyla across all samples. The cultivable bacterial community composition and diversity were strongly affected by plant species. In order to develop potential bioproducts for sustainable agriculture, two sets of experiments were conducted. First, the potential plant growth-promoting rhizobacteria from the reservoir pool indicated above were screened for growth promotion effects on Arabidopsis thaliana ecotype Columbia (Col-0). Four out of 98 selected rhizobacterial strains (strains n, L, K, and Y), from Phalaris arundinacea, Solanum dulcamara, Scorzoneroides autumnalis, and Glycine max, respectively, showed significant growth stimulation effects with regard to total leaf area, total rosette fresh and dry weight, root length, total antioxidative capacity, salinity stress attenuation ability, and total contents of proline and chlorophyll. Strains n and L also showed antagonistic effects against two phytopathogens both in vitro and in planta. Bacterial treatment caused an increase in the transcription of the genes related to plant growth, defense response, and antioxidative activities. The four selected strains were also characterized in pure culture for their plant growth-promoting activities. Surprisingly, one of the best promoters, strain K, did not display the largest number of currently recognized PGP abilities in vitro, but outperformed the most PGP traits possessor, strain n, in planta. Secondly, the four selected strains were further tested on two crop plants, Brassica napus (canola) and Zea mays (corn), for their growth promotion and salt stress alleviation effects. In germination and early seedling growth experiments, the four strains, especially strains L, K, and Y, increased the root length and seedling dry weight in canola under both unstressed and salt stressed conditions; whilst all four strains significantly improved the shoot length (up to 33 %) and fresh weight (up to 25 %) of corn under unstressed conditions. In pot experiments, canola plant biomass and chlorophyll content were increased by all four evaluated strains under initially-sterile conditions. While maize plant biomass and chlorophyll content was significantly increased by all strains under non-sterile conditions in the greenhouse. Only strains n and L increased total antioxidant and proline contents, while strains L, K, and Y increased total plant carbohydrate. Nutrient uptake was also evaluated, with higher levels of Fe and P uptake in maize leaves of plants inoculated with strain n, and increased nitrogen content due to treatment with strains n, L, and Y. Overall, this research (1) highlighted for the first time, a rich reservoir of the diverse rhizobacteria from various crops and uncultivated plants in the region of Sainte-Anne-de-Bellevue, Québec, Canada, (2) demonstrated that four isolates significantly increased plant growth and salt stress resistance in A. thaliana and (3) determined that the same four strains also enhanced the growth of two tested crop plants, canola and maize. This research will help in the development of bioproducts that can be utilized to increase crop growth and yield under both normal and stressful conditions, in an environmentally friendly manner for development of more sustainable, and possible climate change resilient, agricultural systems"--