Tuber indicum shapes the microbial communities of ectomycorhizosphere soil and ectomycorrhizae of an indigenous tree (Pinus armandii)

Abstract

The aim of this study was to investigate the effect of an ectomycorrhizal fungus (Tuber indicum) on the diversity of microbial communities associated with an indigenous tree, Pinus armandii, and the microbial communities in the surrounding ectomycorhizosphere soil. High-throughput sequencing was used to analyze the richness of microbial communities in the roots or rhizosphere of treatments with or without ectomycorrhizae. The results indicated that the bacterial diversity of ectomycorhizosphere soil was significantly lower compared with the control soil. Presumably, the dominance of truffle mycelia in ectomycorhizosphere soil (80.91%) and ectomycorrhizae (97.64%) was the main factor that resulted in lower diversity and abundance of endophytic pathogenic fungi, including Fusarium, Monographella, Ustilago and Rhizopus and other competitive mycorrhizal fungi, such as Amanita, Lactarius and Boletus. Bacterial genera Reyranena, Rhizomicrobium, Nordella, Pseudomonas and fungal genera, Cuphophyllus, Leucangium, Histoplasma were significantly more abundant in ectomycorrhizosphere soil and ectomycorrhizae. Hierarchical cluster analysis of the similarities between rhizosphere and ectomycorrhizosphere soil based on the soil properties differed significantly, indicating the mycorrhizal synthesis may have a feedback effect on soil properties. Meanwhile, some soil properties were significantly correlated with bacterial and fungal diversity in the rhizosphere or root tips. Overall, this work illustrates the interactive network that exists among ectomycorrhizal fungi, soil properties and microbial communities associated with the host plant and furthers our understanding of the ecology and cultivation of T. indicum.

Root‐tip cutting and uniconazole treatment improve the colonization rate of Tuber indicum on Pinus armandii seedlings in the greenhouse

“…Root‐tip cutting, uniconazole treatment and inoculation of T. indicum reduced the microbial diversity in the rhizosphere soil of P. armandii seedlings, particularly on some indicators, including the observed species, Chao1 and Shannon indexes. Our previous study found that inoculation of T. indicum decreased microbial diversity in the rhizosphere soil of P. armandii seedlings under the same conditions (Li et al , ). Of all the major bacterial communities detected, three phyla, namely Proteobacteria, Actinobacteria and Chloroflexi, were dominant in all samples.…”

“…Alphaproteobacteria and Deltaproteobacteria (both in the phylum Proteobacteria) were found to be more abundant in the rhizosphere soil of root tip‐cut or 10 mg l −1 uniconazole‐treated colonized seedlings than in control rhizosphere soil. Previous studies also found that α‐Proteobacteria and γ‐Proteobacteria comprised the predominant components of the bacterial communities of truffles (Barbieri et al , ; Vahdatzadeh et al , ; Li et al , ). Previous studies have demonstrated that Pseudomonas fluorescens (Proteobacteria) improved the establishment and functioning of ectomycorrhizal symbiosis (Dominguez et al , ).…”

“…Pinus armandii Franch., an indigenous Chinese pine, is widely distributed in central and western China where it typically forms ectomycorrhizae with the Chinese black truffle Tuber indicum Cooke & Massee (Geng et al , ; Li et al , ). The ectomycorrhizal fungus T. indicum produces hypogeous fruiting bodies and is considered to be a culinary delicacy due to their unique flavours (Liu, ; Liu et al , ; Cullere et al , ; Vita et al , ).…”

“…Owing to decreases in wild truffle yield as a result of vegetation destruction, forest fires, improper harvesting and other human factors, the synthesis of truffle‐infected plants and truffle cultivation have attracted increasing attention in recent years. The efficient synthesis of ectomycorrhizae is considered to be the basis for the successful cultivation of truffles (Li et al , ).…”

“…Mycorrhiza helper bacteria (MHB) are a group of organisms that could stimulate the formation of mycorrhizal symbiosis (Deveau and Labbé, ). Proteobacteria was found to be the largest and most diverse group in the ectomycorhizosphere of truffles (Li et al , ). Pseudomonas fluorescens belonging to this group has been examined in previous studies to improve mycorrhization of truffle and plant growth (Dominguez et al , ).…”