Cell differentiation and mycorrhizal infection in Dactylorhiza majalis (Rchb. f.) Hunt & Summerh. (Orchidaceae) during germination in vitro
Article first published online: 28 APR 2006
Volume 116, Issue 1, pages 137–147, September 1990
How to Cite
RASMUSSEN, H. N. (1990), Cell differentiation and mycorrhizal infection in Dactylorhiza majalis (Rchb. f.) Hunt & Summerh. (Orchidaceae) during germination in vitro. New Phytologist, 116: 137–147. doi: 10.1111/j.1469-8137.1990.tb00519.x
- Issue published online: 28 APR 2006
- Article first published online: 28 APR 2006
- (Received 16 November 1989; accepted 1 May 1990)
- Dactylorhiza majalis;
- orchid mycorrhiza;
- cell differentiation;
- Epulorhiza sp
Seeds of Dactylorhiza majalis (Rchb. f.) Hunt & Summerhayes were sown in vitro with a compatible fungus. A mycorrhiza was established after infection through the rhizoids of the germinating seedling. Infection through the suspensor did occur, but these hyphae did not form pelotons, and embryo cells in contact with the hyphae were filled with a tannin-like substance.
Germination, and establishment of mycorrhiza, took about 14 days in vitro. From day 9 the protein reserves were hydrolysed, the protein vacuoles coalesced and starch accumulated in plastids. Certain epidermal cells developed nuclei about eight times original volume and produced rhizoids which emerged from day 11. After infection the hyphae formed pelotons in central cells with enlarged nuclei (16–64 times original volume). The intracellular hyphae developed close contacts with the hypertrophied host nuclei. Collapsed pelotons could be observed in cells from day 12, one day after infection. Meristematic activity in the uninfected chalazal end of the seedling began on day 12. On day 28 the first vascular tissue started to develop and on day 35 the beginning of a leafy shoot could be detected.