1 Introduction

184 Y. Desjardins, C. Hernández-Sebastià and Y. Piché
Fig.1A–D. In vitro tripartite culture system used for establishment of mycorrhizae on micropropagated
plantlets. A Inoculation of Ri T-transformed carrot roots (primary inoculation).
B Micropropagation of plantlets. C Transfer of plantlets to rooting medium on Sorbarod
plugs. D Inoculation of plantlets on Sorbarod plugs onto the primary inoculated roots to
establish the tripartite culture (secondary inoculation)
with sterile distilled water under a laminar flow hood (Fig. 1C). After washing,
liquid M medium is added aseptically to the Sorbarods supporting
micropropagated plantlets. The cellulose plugs are then placed in contact
with the mycorrhizal carrot root organs in culture vessels under aseptic
conditions (Figs. 1D and 2B, E). Tripartite cultures are normally grown at