关键词: 银中杨, 环境条件, 内生菌群落, 生态位变异, 扩增子测序

Abstract:

Objective: This paper aims at studying the diversity of endosphere bacterial and fungal microbiome in roots and stems of Populus alba×P. berolinensis grown in three different sites, and the results would provide scientific basis for the study of interactions between plants and microorganisms. Method: The roots and stems of poplar were collected from three different sites:Changweizi village of Linyuan town in Daqing city, Cuohai farm in Qiqihar city and Hancunhe Dongying nursery in Fangshan District. After surface disinfection, microbial DNA was extracted and sequenced by Illumina MiSeq using 16 s rRNA and internal transcribed spacer amplicon (ITS) amplifiers to determine the bacterial and fungal communities associated with the different plant habitats and niches. Results: According to the 97% sequence similarity cut-off level, the reads of bacteria and fungi were clustered into 1541 and 240 OTU, respectively. In comparison with the database, we found that Actinobacteria, Betaproteobacteria, Alphaproteobacteria, Gammaproteobacteria and Bacteroidia were the dominant endophytic bacteria, and the fungal community was dominated by Dothideomycetes, Agaricomycetes, Sordariomycetes and Tremellomycetes. The results of alpha and beta diversity showed that the stem endophytic communities of poplar in Beijing, Daqing and Qiqihar were obviously clustered and could not be distinguished. However, the endophytic community of roots was dependent on plant organs and growth environment. The Mantel test results showed that pH, and soil organic matter (SOM) contents and potassium (K) content were significantly correlated with the microbial communities (P < 0.05). However, the nitrogen (N) and phosphorus (P) content did not appear to be important factors explaining the variance in the communities of poplar root endophytes. We identified the core microbiome in the different organs of poplar grown in different environmental conditions, and obtained a total of 23 core bacteria OTU belonging to 6 classes, and 22 core fungi OTU belonging to 7 classes, respectively. Species indicator analysis revealed seven root endophytic bacterial indicator OTUs:Actinophytocola, Actinoplanes, Pseudonocardia, Rhodomicrobium, Streptomyces, Variovorax and Bradyrhizobium; five stem endophytic bacterial indicator OTUs:Bifidobacterium, Dialister, Faecalibacterium, Micrococcus and Rhodococcus; two root endophytic fungal indicator OTUs:Leptosphaeria and Ilyonectria; three stem endophytic fungal indicator OTUs:Pleosporales, Alternaria and Endosporium. The UpSetR results showed that 51 (3.30%) OTUs of bacteria were shared by 6 groups, and the unique OTU of 6 groups accounted for 4.54-15.44%; one (0.42%) OTU of fungi was shared by 6 groups, and the unique OTU of 6 groups accounted for 2.92-29.17%. Conclusion: The bacterial and fungal community structure depends on the pH, the soil organic matter content and potassium (K) content. Each plant organ represents a unique ecological niche for the endophytic communities. Finally, we have identified the indicator operational taxonomic units (OTU) and core microbiome associated with the different ecological niches of Populus and different environmental conditions. The results provide a basis for further study of host-microbial interactions with the identified abundant OTU of Populus.

Key words: Populus alba×P. berolinensis, environmental condition, endophytic communities, niche differentiation, amplicon Illumina MiSeq