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Title: SPATIAL ANALYSIS OF ENTEROBACTER CLOACAE IN CUCUMBER RHIZOSPHERE USING DIGITAL IMAGE PROCESSING

Author
item Roberts, Daniel
item Dery, Pierre
item SHORT JR, NICK - NASA GREENBELT MD

Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/12/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Analysis of root colonization by plant-beneficial bacteria has been hampered by the time consuming nature of the colonization assays. We developed a method that rapidly determines the position of plant-beneficial bacteria in the soil relative to the plant root. This method is based on digital image processing with computers. The ease with which this technique can be performed compared with current methods and the type of information that this new method provides will allow analysis of root colonization by plant-beneficial bacteria that was too time consuming in the past. This information will be useful to scientists.

Technical Abstract: A spatial analysis technique that coupled digital image processing and genetic tagging with bacterial bioluminescence was developed and used to determine the spatial distribution of Enterobacter cloacae E6(pUCD607) on the rhizoplane and in the rhizosphere of young cucumber plants. The rapidity with which this spatial analysis technique can be performed allows shighly replicated experiments that more accurately estimate the mean surface area of the colonized regions of the rhizoplane and rhizosphere. The mean surface area of the cucumber rhizosphere colonized by E. cloacae E6(pUCD607) decreased with increasing distance from the cucumber seed, which was the point of introduction of the E. cloacae strain. The region of the cucumber rhizosphere colonized by E. cloacae E6(pUCD607) was the region closest to cucumber roots. In two experiments, 99% and 83% of the surface area colonized was on or within 0.8 mm of the cucumber root. Finally, the spatial distribution of E. cloacae E6(pUCD607) in cucumber rhizosphere was highly variable among replicates in individual experiments. This spatial analysis technique does not provide information on total populations of introduced plant-beneficial bacterial strains. However, this technique rapidly provides information on the regions of the rhizoplane and rhizosphere colonized by specific bacteria.