Inhibitory Effects of a Pectin-Enriched Tomato Cell Wall Fraction on Agrobacterium tumefaciens Binding and Tumor Formation

A pectin-enriched soluble cell wall fraction (CWF) prepared from suspension cultured tomato cells inhibits binding of Agrobacterium tumefaciens to these cells. It was hypothesized that the CWF contains the plant surface binding site for A. tumefaciens (NT Neff, AN Binns 1985 Plant Physiol 77: 35-42). Experiments described here demonstrate that tomato CWF inhibited tumor formation on potato slices and Agrobacterium binding to intact tomato cells in a dose-dependent fashion. Boiling the fraction reduced both its binding and tumor inhibitory activities. Tumor inhibitory activity was titrated out by increased concentrations of bacterial inocula with no inhibition apparent at 1 x 10(8) bacteria per milliliter. These results indicate that a tomato CWF is enriched for a putative A. tumefaciens binding site which may also be involved in tumor formation in potato.