1 Introduction

24 S. Declerck, S. Séguin, and Y. Dalpé
Fig. 1. Schematic view of the entrapment (A)andcryopreservation(B) processes. A Starting
from a monoxenic culture, spores are successively isolated with forceps, after solubilization
of the growth medium (1), poured in a 20 gl −1 sodium alginate solution (2), and dropped
in a 0.1 M CaCl2 solution for polymerization (3). After the entrapment of spores, the beads
are removed from the CaCl2 solution, stored overnight at 15 ◦ C and cryopreserved. B Beads
are successively incubated at 4 ◦ C in the cryoprotectant (4), transferred to cryotubes (5),
and cold-treated (6) following a two-step decrease from ambient to final preservation
temperature. Beads are stored at this temperature for 3 h (7), and thereafter retrieved by fast
thawing in warm water (8). The beads are then incubated on the MSR medium, and those
showing spore germination are re-associated with a transformed carrot root (9) to start
a new monoxenic culture. (Declerck and Angelo-Van Coppenolle 2000, with permission of
New Phytologist)