Studies in Cellular Pathology. I. Effects of Cane Gall Bacteria Upon Gall Tissue Cells of the Black Raspberry

Abstract

The bacteria which induce the profusion of galls aerially on fruiting black raspberry canes {Rubus occidentalis) are found primarily between the cell walls of infected tissue. Cytoplasmic elements of the host cell are identical in size and form to these bacteria. The bacteria were differentiated by (1) staining in fixed material; (2) differences in refractivity as observed in fresh sections of gall tissue; (3) reproduction, growth, and gall induction by the bacteria after micro-isolation of single rods from bacterial masses between the walls of gall tissue cells in contrast to the failure to grow or incite division by cytoplasmic bodies identical in size and form to bacteria. The bacteria ramify throughout the gall tissue in the form of zoogleal strands which dissolve the middle lamella. They may also occur in numerous pockets or cavities formed in the gall tissue by lysis of protoplasts and their cell walls. From these pockets and intercellular strands the bacteria were observed in process of discharge prior to the general disintegration of the galls. Cells with which the bacteria are in contact undergo more or less rapid cytolysis. In early stages of gall formation cells distant from the bacteria divide repeatedly. Subsequently intercellular penetration may occur among these cells and in turn other cells at a distance may be incited to division. Eventually cell division ceases, extensive intercellular penetration continues and the gall disintegrates. 2 types of cellular degeneration are descr., cytolysis and autolysis. In cytolysis all elements of the cell are progressively lysed by the contiguous bacteria; the plastids first disappear, then mitochondria, nucleus, fat globules, and frequently part of or the entire cell wall. In autolysis the elements of the chondriome display a pronounced tendency to agglutinate; plastids and mitochondria generally fuse end to end or laterally to form various reticular, solid condensation masses or open 3-dimensional networks of varying pattern. The elements of the chondriome may become vacuolated in this type of cellular degeneration or initial fusion structures may fragment into granular debris.