FIG. 5.

Examples of mixed infection threads following coinoculation of alfalfa with red- and green-fluorescent bacteria. (A) Infection threads containing only gfp-expressing or DsRed-expressing S. meliloti. (B) A sectored infection thread in which the mixed population gave rise to a series of sectors which increase in length along the thread. The tipmost sector advanced into the epidermal cell body, branched (top arrow), and penetrated the underlying cell (bottom arrow), leaving the distal sectors behind. (C) A root hair infected with dual infection threads. Each thread contains sectors of gfp-expressing and DsRed-expressing bacteria. (D) A jumbled type of mixed infection thread. gfp-expressing and DsRed-expressing cells appear randomly mixed throughout the infection thread. (E) Dual infection threads inside a root hair. The threads began as jumbled-type threads but later gave rise to green sectors at their tips (arrows show the sectors in each thread). (Reprinted from reference 60.)