Fig. 1

Optical microscopic images and number of callose fibers secreted from protoplasts of tobacco BY-2 at 3 weeks’ culture (A, C) and A. thaliana at 2 weeks’ culture (B, D) under several conditions. Dashed lines in A and B indicate the secreted fibers. The inset in D represents numbers of callose fibers secreted from protoplasts of white birch (Betula platyphylla) reported previously [6]. The number indicates the average number of fibers per well. Cond. 1–Cond. 7 indicate from condition 1 to condition 7 in Table 1, respectively