# Differentiation and Interconnection of the Bacterial Community Associated with Silene nigrescens Along the Soil-To-Plant Continuum in the Sub-Nival Belt of the Qiangyong Glacier

## TL;DR

This study explores how bacterial communities change from soil to plant parts in a high-altitude glacier region, revealing patterns of diversity and key bacterial players.

## Contribution

The study provides new insights into the differentiation and interconnection of bacterial communities along the soil-to-plant continuum in the sub-nival belt.

## Key findings

- Bacterial diversity and network complexity decrease progressively from rhizosphere soil to leaf endosphere.
- Pseudomonas is a dominant taxon influenced by nitrogen levels and acts as a key connector species in the microbiome.
- Source-tracking analysis shows bacterial migration among soil, root, and leaf compartments.

## Abstract

Plant microbiomes provide significant fitness advantages to their plant hosts, especially in the sub-nival belt. Studies to date have primarily focused on belowground communities in this region. Here, we utilized high-throughput DNA sequencing to quantify bacterial communities in the rhizosphere soil as well as in the root and leaf endosphere compartments of Silene nigrescens to uncover the differentiation and interconnections of these bacterial communities along the soil-to-plant continuum. Our findings reveal that the bacterial communities exhibit notable variation across different plant compartment niches: the rhizosphere soil, root endosphere, and leaf endosphere. There was a progressive decline in diversity, network complexity, network modularity, and niche breadth from the rhizosphere soil to the root endosphere, and further to the leaf endosphere. Conversely, both the host plant selection effect and the stability of these communities showed an increasing trend. Total nitrogen and total potassium emerged as crucial factors accounting for the observed differences in diversity and composition, respectively. Additionally, 3.6% of the total amplicon sequence variants (ASVs) were shared across the rhizosphere soil, root endosphere, and leaf endosphere. Source-tracking analysis further revealed bacterial community migration among these compartments. The genera Pseudomonas, IMCC26256, Mycobacterium, Phyllobacterium, and Sphingomonas constituted the core of the bacterial microbiome. These taxa are shared across all three compartment niches and function as key connector species. Notably, Pseudomonas stands out as the predominant taxon among these bacteria, with nitrogen being the most significant factor influencing its relative abundance. These findings deepen our understanding of the assembly principles and ecological dynamics of the plant microbiome in the sub-nival belt, offering an integrated framework for its study.