Fig. 1

The symbiotic seed germination of G. elata associated with Mycena. a Mature seeds of G. elata. Scale bar = 0.5 mm. b Light micrograph of mature seed. The embryo is covered by a thin testa. Scale bar = 50 μm. c After 1 week of inoculation, a seed becomes swollen. Scale bar = 0.5 mm. d In the enlarged embryo, fungal hyphae have penetrated the embryo through the suspensor end cell (arrow). Scale bar = 50 μm. e After 2 weeks of inoculation, the embryo has ruptured the seed coat, resulting in the formation of a protocorm. Scale bar = 0.5 mm. f Fungal hyphae (arrows) have colonized the basal region of the developing protocorm. Scale bar = 100 μm. g After 12 weeks of inoculation, the elongated protocorm is observed. The basal region of the protocorm is indicated by an arrow. Scale bar = 1 mm. h Light micrograph showing the basal region of the elongated protocorm, and fungal hyphae (arrows) are restricted at the basal region. Scale bar = 60 μm