Scanning electron microscopy of colonization of pear leaves by Pseudomonas syringae pv. syringae

Abstract

A scanning electron microscope study was undertaken to determine how Pseudomonas syringae pv. syringae van Hall colonizes the surface of pear leaves and enters leaf tissue. Bacteria multiplied on the leaf surface, particularly on trichomes and in depressions of the cuticular layer. Masses of bacteria were associated with leaf spots, which appeared 9 days after inoculation under favorable conditions. The pathogen entered leaf tissue through the open base of trichomes and through microscopic fissures in depressions of the cuticular layer. The resident phase of P. syringae pv. syringae probably survives on trichomes of pear leaves.