Effect of symbiotic fungi-Armillaria gallica on the yield of Gastrodia elata Bl. and insight into the response of soil microbial community

Abstract

Armillaria members play important roles in the nutrient supply and growth modulation of Gastrodia elata Bl., and they will undergo severe competition with native soil organisms before colonization and become symbiotic with G. elata. Unraveling the response of soil microbial organisms to symbiotic fungi will open up new avenues to illustrate the biological mechanisms driving G. elata’s benefit from Armillaria. For this purpose, Armillaria strains from four main G. elata production areas in China were collected, identified, and co-planted with G. elata in Guizhou Province. The result of the phylogenetic tree indicated that the four Armillaria strains shared the shortest clade with Armillaria gallica. The yields of G. elata were compared to uncover the potential role of these A. gallica strains. Soil microbial DNA was extracted and sequenced using Illumina sequencing of 16S and ITS rRNA gene amplicons to decipher the changes of soil bacterial and fungal communities arising from A. gallica strains. The yield of G. elata symbiosis with the YN strain (A. gallica collected from Yunnan) was four times higher than that of the GZ strain (A. gallica collected from Guizhou) and nearly two times higher than that of the AH and SX strains (A. gallica collected from Shanxi and Anhui). We found that the GZ strain induced changes in the bacterial community, while the YN strain mainly caused changes in the fungal community. Similar patterns were identified in non-metric multidimensional scaling analysis, in which the GZ strain greatly separated from others in bacterial structure, while the YN strain caused significant separation from other strains in fungal structure. This current study revealed the assembly and response of the soil microbial community to A. gallica strains and suggested that exotic strains of A. gallica might be helpful in improving the yield of G. elata by inducing changes in the soil fungal community.

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 ).…”

“…TE significantly inhibited the growth of fungal strains, such as C. novozelandicum, B. cinerea , and P. digitatum , which is consistent with the decline in the relative abundance of the Chaetomium and Penicillium genera and the absence of Botrytis genus in the rhizosphere. Several previous studies have reported that the bacterial and fungal communities in the cultivated soil of G. elata were significantly altered by Armillaria strains ( Collins et al, 2013 ; Wang et al, 2023 ) and Mycena strains ( Yu et al, 2023 ). Armillaria mellea produces many antibacterial and antifungal compounds, such as sesquiterpene aryl esters and armillaric acid, which exhibit high inhibitory activity against Gram-positive bacteria, yeast, Streptococcus spp., Mucor spp., Trichoderma spp., Rhizopus stolonifer, Fusarium spp., and Gliocladium viren ( Richard, 1971 ; Obuchi et al, 1990 ).…”

“… 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.…”