<i>In-vitro</i> symbiotic germination of seeds of five mycoheterotrophic <i>Gastrodia</i> orchids with <i>Mycena</i> and <i>Marasmiaceae</i> fungi

Abstract

We performed in-vitro germination tests on seeds from five Gastrodia orchids ( G. confusa , G. elata var. elata , G. elata var. pallens , G. nipponica , and G. pubilabiata ) using one Marasmiaceae and two Mycena isolates. Mycena sp. 1 promoted germination of all five Gastrodia orchids, with root and/or tuber formation observed in G. confusa , G. nipponica , and G. pubilabiata . No additional growth was observed in the other two orchids. Mycena sp. 2 induced G. confusa , G. elata var. elata , and G. nipponica germination, whereas Marasmiaceae sp. 1 induced G. nipponica and G. pubilabiata germination. Phylogenetic analyses indicated that the two Mycena isolates represent distinct lineages within the Mycenaceae . Mycena sp. 1 and Marasmiaceae sp. 1 are closely related to Mycena abramsii and Marasmiellus rhizomorphogenus , respectively. Our results imply that Mycena and marasmioid fungi play important roles in early development in Gastrodia species, and that Mycena fungi in particular may be common mycobionts of Gastrodia species. Root and/or tuber development was observed with four plant-fungus combinations, implying that these associations persist throughout the life cycle, whereas G. elata var. elata may require different associates over time. Our findings will contribute to elucidating the mycorrhizal associations of mycoheterotrophic orchids throughout their life cycle.

The role of symbiotic fungi in the life cycle of Gastrodia elata Blume (Orchidaceae): a comprehensive review

“…(A) , Position of Mycena based on 28S LSU ribosomal RNA sequences. Mycena found in Gastrodia confusa by Ogura-Tsujita et al., 2009 , Gastrodia pubilabiata by Kitahara et al., 2022 , and Gastrodia elata from GenBank. (B) , Position of Armillaria based on ITS sequences.…”

“…Currently, only four species (M. osmundicola, M. orchidicola, M. dendrobii, and M. anoectochila) are known to be able to form basidiomata in cultivation and have thus been successfully identified Fan et al, 1996;Guo et al, 1997;Guo et al, 1999). Therefore, these four species have become commonly used fungi for seed germination of G. elata in China (Guo and Wang, 2001;Park and Lee, 2013a;Pan et al, 2015;Kitahara et al, 2022).…”

Variable, life stage-dependent mycorrhizal specificity and its developmental consequences in the fully myco-heterotrophic orchid <i>Cyrtosia septentrionalis</i>

“…A higher degree of specificity has been observed in the mycorrhizal relationships of such orchids (Leake, 1994). However, some terrestrial MH orchids establish mycorrhizal relationships with two or more different mycobionts during successive life history stages (Kitahara et al, 2022;Li et al, 2022). For example, whereas the fully MH orchid Gastrodia elata Blume requires the assistance of the litter decomposer Mycena osmundicola J.E.…”

Two new <i>Mycena</i> section <i>Calodontes</i> species: One newly discovered and the other new to Japan

“…Mycena species have diverse lifestyles, primarily as saprophytes, while certain species are recognized as orchid mycorrhizal symbionts or plant pathogens (Kitahara et al, 2022;Krishnan, 2017). Some Mycena species are known to invade and associate with mosses (Davey et al, 2013).…”