ATTACHMENT OF AGROBACTERIUM-RADIOBACTER TO THE ROOTS OF WHEAT

The process of Agrobacterium radiobacter 5D-1 attachment to wheat root s was investigated in relation to the incubation period, concentration of bacteria in the suspension, and influence of different substances on the process of attachment. It was shown that attachment of nonpatho genic agrobacteria to the roots of monocotyledons (wheat) may be reduc ed or blocked completely by pretreating the bacterial cells with tryps in, glutaraldehyde, cellulase, or N-acetyl-D-glucosamine. Mutants with a reduced ability to produce calcofluor-binding polysaccharides (cfw- type) displayed a lowered capacity for attachment to the wheat roots. Mutants impaired in chemotaxis (che-type) also showed a decreased atta chment capacity. Fibrillike structures of a polysaccharide nature were observed after coincubation of the nonpathogenic agrobacteria with wh eat roots; the cells of bacteria attached to the root surface and to o ne another through these structures. Temporal dynamics of the attachme nt of nonpathogenic agrobacteria to the roots of monocotyledons was of the same character as the dynamics of attachment of pathogenic agroba cteria to the cell surface of dicotyledonous plants.