Dynamics of fungal communities during Gastrodia elata growth

Abstract

Background Gastrodia elata is a widely distributed achlorophyllous orchid and is highly valued as both medicine and food. Gastrodia elata produces dust-like seeds and relies on mycorrhizal fungi for its germination and growth. In its life cycle, G. elata is considered to switch from a specific single-fungus relationship ( Mycena ) to another single-fungus relationship ( Armillaria ). However, no studies have investigated the changes in the plant-fungus relationship during the growth of G. elata in the wild. In this study, high-throughput sequencing was used to characterize the fungal community of tubers in different growth phases as well as the soils surrounding G. elata . Results The predominant fungi were Basidiomycota (60.44%) and Ascomycota (26.40%), which exhibited changes in abundance and diversity with the growth phases of G. elata . Diverse basidiomycetes in protocorms (phase P) were Hyphodontia , Sistotrema , Tricholoma , Mingxiaea , Russula , and Mycena , but the community changed from a large proportion of Resinicium bicolor (40%) in rice-like tubers (phase M) to an unidentified Agaricales operational taxonomic unit 1(OTU1,98.45%) in propagation vegetation tubers (phase B). The soil fungi primarily included Simocybe , Psathyrella , Conocybe , and Subulicystidium . Three Mycena OTUs obtained in this study were differentially distributed among the growth phases of G. elata , accounting for less than 1.0% of the total reads, and were phylogenetically close to Mycena epipterygia and M. alexandri . Conclusions Our data indicated that G. elata interacts with a broad range of fungi beyond the Mycena genus. These fungi changed with the growth phases of G. elata . In addition, these data suggested that the development of the fungal community during the growth of G. elata was more complex than previously assumed and that at least two different fungi could be involved in development before the arrival of Armillaria . Electronic supplementary material The online version of this article (10.1186/s12866-019-1501-z) contains supplementary material, which is available to authorized users.

Evolutionary histories and mycorrhizal associations of mycoheterotrophic plants dependent on saprotrophic fungi

“…The litter-decaying fungus, Mycena , induces seed germination, whereas the wood-decaying Armillaria supports further development of the mature plant (Xu and Guo 2000 ). A recent high-throughput sequencing study suggests that more diverse fungal groups than previously assumed are involved at the juvenile stage of G. elata (Chen et al 2019 ). Partner switching also seems to occur in Cyrtosia septentrionalis , the adult stage of which is associated with Armillaria (e.g., Hamada 1939 ).…”

Temporal turnover in mycorrhizal interactions: a proof of concept with orchids

“…Ontogenetic shifts (intrinsic) are developmentally programmed changes in a plant's physiological needs independently of extrinsic changes, such as growth from juvenile to adult (Rasmussen et al ., 2015), or from vegetative to reproductive life stages. For example, a field study on the orchid Gastrodia elata showed different fungal operative taxonomic units (OTUs) between protocorms and tubers, a later developmental stage (Chen et al ., 2019). As the two developmental stages occurred simultaneously, temporal variation in extrinsic factors can be ruled out as a cause for the switch.…”

Increasing fungal abundance in the substrate enhances seed germination in a fully mycoheterotrophic orchid

“…However, high-throughput sequencing of both juvenile and adult stages ofG. elata showed that the juvenile stage associated with more diverse fungal groups than Mycena only (Chen et al, 2019). A similar pattern of total replacement has been found in Cyrtosia septentrionalis , another mycoheterotrophic orchid associated with wood-decaying fungi.…”

“…A similar result was found in Gastrodia elata , which is mainly found in broadleaved forests. Chen et al (2019) showed that besides Mycenaceae, a broader spectrum of fungal associations, such as Resinicium ,Hyphodontia , Sistotrema , Tricholoma andRussula was detected in the juvenile stage of G. elata .…”