Unravelling the plant growth promotion potential of the bacterial endophytic microbiota associated with Canola (Brassica napus) plants

Plants have coevolved with a diverse community of associated microorganisms, including the bacterial endophytic microbiota, which are microorganisms that live in plant internal tissues without causing apparent damage. The endophytic bacterial microbiota plays an important role in the health and growth of plants and its constituents are excellent candidates for bioinoculant development. Canola (Brassica napus) is the third most common oil-producing crop worldwide. In Uruguay, this crop is cultivated for oil and biodiesel production, but its optimal growth requires large amounts of chemical fertilization, which entails a deleterious environmental impact. This problem stresses the need for the development of new sustainable technologies in canola production. The aim of this work was the construction and characterization of a bacterial collection associated with the internal tissues of common canola cultivars grown in Uruguay as a starting point for bioinoculant development. To this end, a culturable endophytic bacterial collection of canola cultivars grown in Uruguay (Trapper and Igranola103) was constructed and characterized (in vitro and in vivo). Selected isolates of the collection were identified and assigned to the Enterobacter, Pseudomonas, Arthrobacter, and Pantoea genera. In addition, several plant growth-promoting traits were identified in the isolates of the collection, including Fe, P, K solubilization, auxin production, and the potential ability to fix N. Moreover, isolates related to the Pseudomonas and Arthrobacter genera were able to promote plant growth. This work represents the initial step toward bioinoculant development based on endophytic plant growth-promoting bacteria for canola cultivars grown under Uruguayan agroclimatic and soil conditions.