The genus Stenotrophomonas is of high medical, ecological and biotechnological interest due to the versatility of the different species. Root colonisation and plant growth promotion by Stenotrophomonas rhizophila DSM14405T in different crop species and at different salinities were investigated. Plant growth promotion was most significant in solanaceous crops (tomato, sweet pepper). In non-sterile systems and ambient humidity, colonisation of aboveground plant parts was strongly dependent on plant species; epiphyllic populations on tomato were 4-5 orders of magnitude higher than epiphyllic populations on sweet pepper and cotton. Rhizosphere populations were uniformly high irrespective of plant species (104 CFU/g root fresh weight). However, in sweet pepper they declined sharply from 104 to 101 CFU/g root fresh weight with increasing soil salinity in non-sterile soil (0-1% NaCl). Rhizosphere populations were higher (∼108 CFU/g FW) and the decline with salinity less pronounced in sterile (autoclaved) soil. A similar decline with salinity could be observed in the above-ground populations. Although population sizes where lower, plant growth promotion by S. rhizophila DSM14405T was more pronounced in non-sterile soil than in sterile soil. Only there the effect was consistent across all salinities so that a linear regression model with S. rhizophila DSM14405T as significant growth promoting factor could be fitted. The greater effect in nonsterile soil points to an indirect plant growth promotion effect of S. rhizophila DSM14405T, possibly via the elimination of deleterious components of the rhizosphere flora.
|Publication status||Published - 2010|
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