Blocking of Attachment to Cell Wall as a Resistance Response to Crown Gall Bacteria Agrobacterium tumefaciens by Roses

概要

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There are varietal differences among rose cultivars in their resistance to crown gall disease, caused by Agrobacterium tumefaciens. Since attachment of A. tumefaciens to host plant cells at the wound site is one of the main steps in infection, we observed the attachment of the bacteria to high and low resistant roses. High resistant roses 'PEKcougel' and 'Lifirane', and low resistant roses 'Dukat', Rosa multiflora 'Matsushima No. 3', and R. canina 'Pfänder' were inoculated with A. tumefaciens GOU1. Scanning electron microscopy showed that non-inoculated high resistant roses secreted substances that aggregated to form masses of secretions that became thick layers with time. Although lowly resistant roses also secreted some substances, the amounts were far less than those in the high resistant roses and most of the cut cell surfaces remained exposed. On inoculated low resistant roses, elaboration of fibrils by A. tumefaciens not only made them attached to the surface of the host cell, but also entrapped other bacteria to form clumps. Contrarily, highly resistant roses enmeshed the bacteria by their secretions, thus preventing direct contact of the bacteria to the wound surfaces. On the surface of heat-killed plant cells, no mass of secretion was formed, resulting in the attachment of A. tumefaciens in both highly and lowly resistant roses.
園芸学会の論文