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Updated: August 14, 2017
Actually, the bacterium only carries the gall-causing entity, a plasmid, that contains its own genetic material. After the bacterium enters the host, the plasmid DNA is transferred into the host plant cell where it stimulates the production of more plant cells.
Galls or overgrowth (1/4 inch to several inches in diameter) of host plant tissue typically form at the soil line but also can form on branches or roots.
Galls are initially white, spherical, and soft but darken with age as outer cells die.
Galls can either be almost entirely on the surface of the plant and easily detached or can be almost indistinguishable from normal plant tissue except for its greatly enlarged appearance.
The bacterium survives and persists in the soil for many years. It invades recent wounds on stems or roots. Swelling can be seen 14 days following entry. Tissue near the gall is crushed. If vascular tissue is crushed, wilting can result from the restricted water movement.
Old crown gall
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