The invasion of pea roots, pisum sativum l., by soil microorganisms, Acanthamoeba palestinensis (reich) and pseudomonas SP

Pea roots (Pisum sativum L. cultivar Tall Sugar White) were inoculated with Pseudomonas sp., isolated from the roots of Timothy grass (Phleum pratensis L.). Microscopic examination showed that the bacterium had invaded many epidermal and outer cortical cells of the root. The presence of the soil amoeba, Acanthamoeba palestinensis (Reich), which readily ingests Pseudomonas sp., did not alter the root damage. The amoebae were also found in the epidermis and outer cortex of pea roots. No amoebae were found inside pea roots when Pseudomonas sp. was absent. Bacterial invasion also occurred in pea roots grown in garden soil previously sterilized by γ-irradiation and inoculated with Pseudomonas sp., but not in the same soil inoculated and unsterilized. Timothy grass roots were similarly uninfected in inoculated unsterilized garden soil.