An exploration of mechanism of high quality and yield of Gastrodia elata Bl. f. glauca by the isolation, identification, and evaluation of Mycena

Abstract

Gastrodia elata Bl. f. glauca is an important traditional Chinese medicinal plant. The yield and quality of Gastrodia elata Bl. have significantly decreased due to multigenerational asexual reproduction. Therefore, it is necessary to have sexual reproduction of Gastrodia elata Bl. to supplement the market supply. Seeds of G. elata Bl. have no endosperm, and their sexual reproduction depends on the nutrients provided by the embryo cells infected by Mycena fungi to complete seed germination. However, Mycena fungi are small and have many species, and not all Mycena fungi can promote the germination of G. elata Bl. seeds. Therefore, it is of great significance to isolate and identify suitable germination fungi and explore the mechanism for improving the production performance and yield, and quality of G. elata Bl. Six closely related Mycena isolates, JFGL-01, JFGL-02, JFGL-03, JFGL-04, JFGL-05, and JFGL-06, were isolated from the leaves and protocorms of G. elata Bl. f. glauca and were identified as Mycena purpureofusca. The mycelial state and number of germinating protocorms were used as indicators to preferentially select Mycena fungi, and it was concluded that JFGL-06 had the best mycelial state and ability to germinate G. elata Bl. seeds. Finally, a mechanism to increase the yield of G. elata Bl. was explored by comparing the changes in nutrient elements and microbial diversity in the soil around G. elata Bl. with different strains. JFGL-06 proved to be an excellent Mycena fungal strain suitable for G. elata Bl. f. glauca. Compared with the commercial strain, JFGL-06 significantly increased the C, N, Na, Mg, S, Cl, K, Ca, and Fe contents of the soil surrounding the protocorms of G. elata Bl. f. glauca. JFGL-06 improved the composition, diversity, and metabolic function of the surrounding soil microbial community of G. elata Bl. f. glauca protocorms at the phylum, class, and genus levels, significantly increased the relative abundance of bacteria such as Acidobacteria and fungi such as Trichoderma among the dominant groups, and increased the abundance of functional genes in metabolic pathways such as nucleotide metabolism and energy metabolism. There was a significant reduction in the relative abundance of bacteria, such as Actinomycetes, and fungi, such as Fusarium, in the dominant flora, and a reduced abundance of functional genes, such as amino acid metabolism and xenobiotic biodegradation and metabolism. This is the main reason why the JFGL-06 strain promoted high-quality and high-yield G. elata Bl. f. glauca in Changbai Mountain.

Features of bacterial and fungal communities in the rhizosphere of Gastrodia elata cultivated in greenhouse for early harvest

“…Mortierella rishikesha maintained highest relative abundance (>9%) in the rhizosphere throughout the growth stages of G. elata , indicating that it might be a core fungal species under greenhouse conditions. A high relative abundance of Mortierella has also been observed in the fungal communities of G. elata by Wang et al (2023) and Yu et al (2023) . Mortierella species in agricultural soils, the rhizosphere, and vegetable tissues are plant growth-promoting fungi ( Ozimek and Hanaka, 2020 ).…”

“…In this study, we found that Proteobacteria was the predominant phylum in the rhizosphere of G. elata , followed by Acidobacteria, which corresponds to the bacterial communities in the cropping soil of G. elata ( Yuan et al, 2020 ) and in the surrounding soil of G. elata protocorms ( Yu et al, 2023 ). Yu et al (2023) reported that Proteobacteria showed a positive relationship with soil ammonium nitrogen content in the soil surrounding G. elata.…”

“…In this study, we found that Proteobacteria was the predominant phylum in the rhizosphere of G. elata , followed by Acidobacteria, which corresponds to the bacterial communities in the cropping soil of G. elata ( Yuan et al, 2020 ) and in the surrounding soil of G. elata protocorms ( Yu et al, 2023 ). Yu et al (2023) reported that Proteobacteria showed a positive relationship with soil ammonium nitrogen content in the soil surrounding G. elata. In this study, Paraburkholderia , Rhizomicrobium , Sphingomonas , and Rhizobium that belong to Proteobacteria, Edaphobacter belonging to Acidobacteria, and Mucilaginibacter belonging to Bacteroidetes maintained high relative abundances (>1%) during the growth of G. elata under greenhouse.…”

“…The seeds of G. elata do not contain an endosperm, so their germination and development into protocorms only occur when they are provided with adequate nutrients through the digestion of fungal strains of Mycena spp. The juvenile tubers of G. elata subsequently grow through a symbiotic association with a mycorrhizal fungus Armillaria mellea to yield mature tubers ( Park and Lee, 2013 ; Chen et al, 2019 ; Yu et al, 2022 , 2023 ).…”

“… Zheng et al (2023) compared the diversity and structure of endophytic bacterial communities in G. elata tubers grown in various geographical regions. The effects of different Armillaria strains ( Yu et al, 2022 ; Wang et al, 2023 ) and Mycena strains ( Yu et al, 2023 ) on the structure and metabolic function of soil microbial communities, as well as the quality and productivity of G. elata have also received recent research attention.…”