Mycorrhizosphere Bacteria, Rahnella sp. HPDA25, Promotes the Growth of Armillaria gallica and Its Parasitic Host Gastrodia elata

Abstract

Gastrodia elata is an entirely heterotrophic plant, the growth of which is completely reliant on Armillaria gallica, an orchid mycorrhizal fungus. To avoid damaging ecosystems, G. elata cultivation is shifting from woodland to farmland. However, whether the microbial community structure remains stable during this conversation is unknown. Here, we cultivated G. elata in woodland or farmland and found that woodland-cultivated G. elata produced a greater yield and larger tuber size. The relative abundance of Rahnella was 22.84- and 122.25-fold higher in woodland- and farmland-cultivated soil samples, respectively, than that in uncultivated soil samples. To investigate how Rahnella impacts the growth of G. elata and establishes symbiosis with Armillaria gallica, three Rahnella spp. strains (HPDA25, SBD3, and SBD11) were isolated from mycorrhizosphere soil samples. It was found that these strains, especially HPDA25, promoted the growth of A. gallica. Ultra-performance liquid chromatography coupled to a triple quadrupole mass spectrometry analysis detected the indole-3-acetic acid with 16.24 ng/ml in HPDA25 fermentation solution. Co-culturing with the strain HPDA25 or exogenous indole-3-acetic acid increased the branching and fresh weight of rhizomorphs and the growth rate and extracellular laccase activity of A. gallica, compared with A. gallica cultured alone. The results of RNA-seq and quantitative real-time polymerase chain reaction analysis showed that co-culturing A. gallica with HPDA25 increased the expression level of the genes including hydrophobin, SUR7/PalI family, and pectin methylesterase, whereas decreased the expression levels of glycolysis-related genes. Furthermore, co-culturing with the strain HPDA25, A. gallica promotes the growth of G. elata and enhances the tuber size of G. elata. These results provide new insights into an orchid mycorrhizal symbiosis and the cultivation of G. elata.

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

“…[42], which has different effects on the yield of G. elata Bl. [23]. After multiple generations of Armillaria, its activity and ability to provide nutrients decreased, thus resulting in a decrease in G. elata Bl.…”

“…Seven phylogenetic branches can coexist with G. elata Bl. [21][22][23][24][25][26]. New Armillaria species in China are constantly being discovered.…”

A Mycorrhizal Bacteria Strain Isolated From Polyporus umbellatus Exhibits Broad-Spectrum Antifungal Activity

“…Many bacteria found around plant roots (rhizosphere and/or mycorrhizosphere) have the ability to promote plant growth and are therefore known as plant growth-promoting bacteria (PGPB) ( Sessitsch et al, 2010 ; Liu et al, 2022 ). Few studies have reported the ability of PGPB to promote plant growth and its antagonistic potential against a variety of fungal pathogens.…”

“…Genomic DNA of the isolate was extracted according to the method of Welington et al ( Araujo et al, 2002 ). The 16S rRNA gene was amplified by PCR using a pair of universal primers, 27F (5′-CAGAGTTTGATCCTGGCT-3′) and 1492R (5′-AGGAGGTGATCCAGCCGCA-3′), as previous described ( Baik et al, 2008 ; Liu et al, 2022 ). The DNA gyrase subunit B ( gyrB ) gene was amplified with primers up-1 (5′-GAAGT CATCATGACCGTTCTGCAYGCNGGNGGNAARTTYGA-3′) and up-2r (5′-AGCAGGATACGGATGTGCGAGCCRTCNACR TCNGCRTCNGTCAT-3′) ( Yamamoto and Harayama, 1995 ; Duan et al, 2021 ).…”

“…(5 -AGGAGGTGATCCAGCCGCA-3 ), as previous described (Baik et al, 2008;Liu et al, 2022). The DNA gyrase subunit B (gyrB) gene was amplified with primers up-1 (5 -GAAGT CATCATGACCGTTCTGCAYGCNGGNGGNAARTTYGA-3 ) and up-2r (5 -AGCAGGATACGGATGTGCGAGCCRTCNACR TCNGCRTCNGTCAT-3 ) (Yamamoto and Harayama, 1995;Duan et al, 2021).…”