In vivo gene expression of Pseudomonas putida KT2440 in the rhizosphere of different plants.
Bottom Line: Using the IVET technology we investigated which KT2440 genes were expressed in the rhizosphere of four different plants: pine, cypress, evergreen oak and rosemary.Another 40 fusions were found to correspond to likely promoters that encode antisense RNAs of unknown function, some of which were isolated as fusions from the bacteria recovered in the rhizosphere from all of the plants, while others were specific to one or several of the plants.The results obtained in this study suggest that plant-specific signals are sensed by KT2440 in the rhizosphere and that the signals and consequent gene expression are related to the bacteria's successful establishment in this niche.
Affiliation: Bio-Iliberis Research and Development, I+D Department, 18210, Peligros, Granada, Spain.Show MeSH
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Mentions: Although most of the transcriptional fusions were isolated several times from independent samples, we performed an additional set of assays to verify that the isolated clones indeed exhibited asd expression in the rhizosphere from the promoters cloned in the transcriptional fusions. With this aim we randomly chose clones containing a transcriptional fusion found in all plants or only in some of the plants and carried out rhizosphere colonization assays with pure cultures of these clones. The results were compared with those obtained with P. putida Δasd carrying pOR1 (without insert). In all cases, clones with transcriptional fusions kept their population sizes at a level that was at least three orders of magnitude higher than P. putida Δasd with the empty plasmid (Fig. 3). When clones with transcriptional fusions found in only one type of plant were tested in the rhizosphere of another plant, differences in the cell densities were significant, around two orders of magnitude of variation (Table 2).
Affiliation: Bio-Iliberis Research and Development, I+D Department, 18210, Peligros, Granada, Spain.