Detection of colonization by pseudomonas PsIA12 of inoculated roots of Lupinus albus and Pisum sativum in greenhouse experiments with immunological techniques

The plant-growth-promoting, non-diazothrophic strain Pseudomonas PsIA12, isolated from wheat rhizosphere, was used as inoculum for the legumes Lupinus albus and Pisum sativum. Root colonization of 8 week-old plants, under non-sterile greenhouse conditions, was assessed in both legumes by a strain-specific polyclonal antiserum and a sensitive chemoluminescence immunoassay. Although the autochtone bacterial colonization of the rhizoplane as well as of the root interior was similar in both plants, the roots of Lupinus albus were colonized by Pseudomonas PsIA12 more intensively than the roots of Pisum sativum. In the roots of Lupinus albus, the introduced strain contributed 50%, in pea roots only about 1% to the total bacterial population. Using the immunogold labelling technique, microcolonies of the introduced strain were detected in the rhizoplane and in the inner root tissue of Lupinus albus.