Early development of canola seedlings in the presence of the plant growth-promoting rhizobacterium Pseudomonas putida GR12-2

The early development of seedlings from canola seeds treated with MgSO4, P. putida GR12-2 or its mutant P. putida GR12-2/acd68 lacking ACC deaminase activity (seed inoculation), or the growth of seedlings planted in soil containing one of these treatments (soil inoculation) was assessed. Root and shoot lengths, fresh and dry wt, and the chlorophyll and protein contents of shoots were monitored in unstressed control seedlings and in seedlings growing in a saline soil or exposed to cold night temperatures. Under all conditions including salt or temperature stress, the wild-type bacterium, but not the mutant, promoted root growth, and in those experiments in which the treatment was added to the soil, the wild-type bacterium promoted shoot growth.