Assessing Root Colonization of Tomato Seedlings by a Pathogenic Bacterium Using Viable Cell Counts

Take containers holding tomato seedlings grown in sterile sand.

The seedling roots are inoculated with either a cellulose-producing wild-type or a cellulose-deficient mutant strain of a plant-pathogenic bacterium.

Remove the sealing material from one container, invert it on sterile paper, and tap to release the sand cylinder containing the plant.

Split the sand cylinder lengthwise to expose the root.

Then, dip the root into a sterile buffer and shake to dislodge loosely attached bacteria.

Repeat the process for the other root.

Transfer the washed roots to a fresh buffer. Sonicate them to release tightly adhered bacteria.

Use these sonicated suspensions to prepare serial dilutions, plate them on agar, and incubate to allow viable bacteria to form colonies.

Higher viable counts in the wild-type strain, compared to the cellulose-deficient mutant, highlight the critical role of cellulose fibrils in promoting bacterial adhesion to the root surface.

To determine the number of viable bacteria found to plants grown in sand, begin by removing the sealing material from the top and bottom of the container.

Place the container over a piece of sterile paper and gently knock the container against the surf