The Primary Root Epidermis of Panicum virgatum L. II. Fine Structural Evidence Suggestive of a Plant-Bacterium-Virus Symbiosis

Abstract

Roots of P. virgatum seedlings have been found to be associated invariably with a symbiotic bacterial species. These bacteria were found both on the surface of, and buried in, the outer walls of the more basal elongating epidermal cells. Often the morphology of the wall-associated bacteria suggested that they were infected with a virulent phage. Other observations included the sudden appearance of virus-like particles in the cytoplasm of these basal elongating epidermal cells. Since the appearance of phage-infected bacteria was found to coincide with the appearance of the cytoplasmic virus-like particles, and since these two events also coincided with the culmination of the ontogeny of large epidermal cytoplasmic inclusions (ECI) in these cells, it has been suggested that these three events may be related.