Mosses as extraordinary reservoir of microbial diversity: a comparative analysing of co-occurring 'plant-moss twins' in natural alpine ecosystem

Abstract

The decline in plant biodiversity is evident at global scale, but little is known about the loss of microbial diversity associated with diverse plant phyla and their influencing factors. This study investigates the microbial diversity associated with mosses and co-occurring vascular plants in the Alpine ecosystem, focusing on 52 plant "twins" growing on contrasting soil types (carbonate and silicate). Despite co-occurring in the same soil, mosses harbored significantly higher microbial richness and diversity than vascular plants. Across all samples, mosses supporting a total of 3,435 bacterial ASVs and 1,174 fungal ASVs. In contrast, vascular plants hosted a total of 1,760 bacterial ASVs and 911 fungal ASVs. Plant phyla strongly influenced microbial community composition, with vascular plants exhibiting a selective microbial assembly strategy, while mosses showed greater environmental influence. Soil type significantly influenced microbial composition in both plant types, with carbonate soils supporting greater bacterial richness, particularly in mosses. Linear discriminant analysis effect size (LEfSe) analysis highlighted consistent enrichments of Proteobacteria, i.e., Sphingomonadales, Rhizobiales, Burkholderiales and, Pseudomonadales, in vascular plants across soil types, whereas mosses displayed distinct microbial enrichment patterns between carbonate and silicate soils, suggesting a higher environmental connectedness. Our findings demonstrated that plant phyla are a major determinant of the phyllosphere microbiota, and that mosses represent a currently untapped source of microbial biodiversity. This study highlights the importance of considering both host traits and environmental factors for protecting microbial biodiversity and implementing them in global strategies for restoring biodiversity.

Keywords: Alpine ecosystem; Moss and vascular plant microbiomes; Phyllosphere; Soil type and microbial diversity.

Fig. 1

Phyllosphere microbial diversity and community composition differences between mosses and vascular plants. (a) Shannon diversity of bacterial communities, in mosses (blue) compared to vascular plants (orange) (ANOVA, P = 6.49e-10, R² = 0.347). (b) Shannon diversity of fungal communities, in mosses and vascular plants (ANOVA, P = 0.063, R² = 0.047). (c) Species richness (ASVs) of bacterial communities across individual samples. The horizontal dashed lines represent the mean richness for each group (Moss: dashed blue line, Vascular Plant: dashed orange line) (d) Species richness (ASVs) of fungal communities across individual samples. (e) Principal Coordinate Analysis (PCoA) of bacterial community composition based on Bray-Curtis dissimilarities (PERMANOVA, P = 0.001, R² = 0.048). (f) PCoA of fungal community composition based on Bray-Curtis dissimilarities, (PERMANOVA, P = 0.001, R² = 0.032)

Fig. 2

Influence of soil type (carbonate vs. silicate) on phyllosphere microbial diversity and community composition of mosses (blue) and vascular plants (orange). (a) Shannon diversity of bacterial communities in mosses and vascular plants across carbonate and silicate soils (ANOVA, P = 0.0458; P = 0.261). (b) Shannon diversity of fungal communities in mosses and vascular plants across soil types (ANOVA, P = 0.161; P = 0.435). (c) Species richness (ASVs) of bacterial communities across individual samples, separated by soil type. The horizontal dashed lines represent the mean richness for each group (Moss: dashed blue line, Vascular Plant: dashed orange line). (d) Species richness (ASVs) of fungal communities across individual samples, separated by soil type, with dashed lines representing the mean richness for each group. (e) Principal Coordinate Analysis (PCoA) of bacterial community composition based on Bray-Curtis dissimilarities by soil type for both plant types (PERMANOVA, P = 0.001, R² = 0.086). (f) Principal Coordinate Analysis (PCoA) of fungal community composition based on Bray-Curtis dissimilarities, by soil type (PERMANOVA, P = 0.001, R² = 0.064). Carbonate soils are indicated by circles and silicate soils by triangles

Fig. 3

Differentially abundant bacterial and fungal orders in the phyllosphere of mosses (blue) and vascular plants (orange) based on Linear Discriminant Analysis Effect Size (LEfSe). (a) Bacterial orders enriched in mosses and vascular plants across all soil types. (b) Fungal orders enriched in mosses and vascular plants across all soil types. (c) Bacterial orders enriched in both mosses and vascular plants specifically in carbonate soils. (d) Fungal orders enriched in both mosses and vascular plants specifically in carbonate soils. (e) Bacterial orders enriched in both mosses and vascular plants specifically in silicate soils. (f) Fungal orders enriched in both mosses and vascular plants specifically in silicate soils. The length of the bar represents the effect size (LDA score)