Abstract:

Aims: Phyllosphere microorganisms play a crucial role in host plant health, adaptability, and ecosystem stability. However, research on the diversity characteristics and driving mechanisms of phyllosphere microbial communities in temperate desert shrubs remains limited. 

Methods: This study focused on three typical desert shrubs in the Gurbantunggut Desert [Calligonum leucocladum, Ephedra przewalskii, and Haloxylon persicum]. Using 16S rRNA high-throughput sequencing technology, combined with PCoA analysis, redundancy analysis, and null models, we systematically examined the diversity characteristics of phyllosphere bacterial communities and the relative contributions of deterministic and stochastic processes to their assembly. 

Results: The results showed that both host plant identity and geographic location significantly influenced the diversity and structure of phyllosphere bacterial communities (P < 0.05), with host identity explaining a substantially higher proportion of the variance (R² = 0.766) compared to geographic location (R² = 0.046). The independent contribution of plant functional traits to the variation in phyllosphere bacterial community structure (9.39%–47.45%) was far greater than that of climatic factors (0%–0.38%) and soil properties (1.23%–6.21%). Stochastic processes (75.53%–95.24%) dominated the assembly of phyllosphere bacterial communities, with ecological drift (60.01%–91.43%) being the core driving force. Co-occurrence network analysis revealed tightly connected network structures and significant modularity features in the phyllosphere bacterial communities of different desert shrubs. 

Conclusion: This study elucidates the diversity characteristics and assembly mechanisms of phyllosphere bacterial communities in arid desert shrubs, highlighting the key role of host functional traits, and provides theoretical foundations and practical guidance for adaptive management strategies of desert ecosystems under global climate change.

Key words: Desert shrubs, Phyllosphere bacteria, Community diversity, Community assembly, Plant functional traits, Co-occurrence network