Abstract
Gymnadenia conopsea (L.) R. Br. is an important perennial terrestrial photosynthetic orchid species whose microbiomes are considered to play an important role in helping its germination and growth. However, the assemblage of G. conopsea root-associated microbial communities is poorly understood. The compositions of fungal and bacterial communities from the roots and corresponding soil samples in G. conopsea across distinct biogeographical regions from two significantly different altitudes were characterized at the vegetative and reproductive growth stages. The geographical location, developmental stage and compartment were factors contributing to microbiome variation in G. conopsea. Predominant fungal taxa include Ascomycota, Basidiomycota, Mortierellomycota and Chytridiomycota, whereas Proteobacteria, Bacteroidetes, Acidobacteria, Actinobacteria, Verrucomicrobia, Chloroflexi, TM7 and Planctomycetes were predominant bacterial taxa. Using G. conopsea as a model, the structural and functional composition in G. conopsea root-associated microbiomes were comprehensive analyzed. Contrary to previous studies, biogeography was the main factor influencing the microbial community in this study. Besides, compartment and developmental stage should also be considered to analyze the variation of microbiota composition. Although the microbial composition varied greatly by location, the symbiotic microorganisms of G. conopsea still have certain specificity. This study gives an abundant information of G. conopsea root-associated microbiomes and provides new clues to better understanding the factors affecting the composition and diversity of fungal/bacterial communities associated with orchids. Our results also laying a foundation for harnessing the microbiome for sustainable G. conopsea cultivation. Moreover, these results might be generally applicable to other orchidaceae plants.
Highlights
Terrestrial plants harbor abundant and diverse microbes that affect plant distribution, growth and health by different ways
12.1 and 5.1 million high-quality sequences were obtained from the ITS2 and 16S rRNA gene sequencing data, respectively. 6,667,165 and 5,460,693 ITS2 tags and 3,883,175 and 1,206,448 16S rRNA tags were obtained from the corresponding soil and root sample, respectively (Supplementary Tables S2, S3)
For the microbial richness Chao index estimated based on the fungal dataset, it revealed that the microbial richness from soil to the root was decreased in both sites (Figure 1A, P < 0.05), except the soil sample in DXAL at reproductive growth stage
Summary
Terrestrial plants harbor abundant and diverse microbes that affect plant distribution, growth and health by different ways. Previous research revealed that plants can recruit beneficial/specific communities to cope with pathogen encounters, modify the nutrient status as well as adapt to new or changing environmental conditions The spatial distribution of soil microorganisms, such as microbial mutualists and pathogens, probably acts as a driver of spatial patterns of palnt species and plant community diversity (Ettema and Wardle, 2002). These communities can be taken as plant host’s second genome, providing a wide diversity of promising functional capacities (Berendsen et al, 2012; Turner et al, 2013). This work may enable new plant management approaches and provide novel tools to improve the robustness of crop plant performance
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