Response of phyllosphere bacteria and fungi of Reaumuria trigyna to seasonal change

Abstract:

[Background] Phyllosphere is home to various and abundant microorganisms. Thanks to the specific functions, phyllosphere microorganisms survive in the presence of stresses and they influence the physiological and ecological characteristics of host plants. In addition, they are affected by environmental heterogeneity. [Objective] The microbial community in plant phyllosphere is dynamic, and clarifying the effect of seasonal alternation on structure of the microbial community is of great significance for in-depth understanding of plant-microbe-environment interactions. [Methods] Reaumuria trigyna is a recretohalophyte in desert steppe in Ordos. We determined the physico-chemical properties of leaf surface and carried out high-throughput sequencing of phyllosphere bacteria and fungi in spring and autumn. [Results] The water content, pH, and electric conductivity of soil under the canopy of R. trigyna and the electric conductivity, Na⁺ content, and K⁺ content on leaf surface were significantly different between spring and autumn. The operational taxonomic units (OTUs), Shannon, Chao1 and ACE indices of phyllosphere bacteria were in positive correlation with salt content of soil and leaf surface. The relative abundance of Cyanobacteria and Bacteroidota was higher in spring, while the relative abundance of Proteobacteria, Actinobacteriota, and Ascomycota in autumn was higher than that in spring. Bradyrhizobium, Novosphingobium, and Edaphobaculum were in positive correlation with leaf surface salinity, while Modestobacter, Adhaeribacter, and Bacillus showed negative correlation. [Conclusion] The asynchronous change of water and salt in soil under the canopy of R. trigyna caused by seasonal alternation increased the accumulation of salt on the leaf surface of R. trigyna, further affecting the phyllosphere microbial diversity and community composition. This study reveals the response of phyllosphere bacteria and fungi of R. trigyna to seasonal alternation, which is expected to provide a theoretical reference for further elucidating the assembly strategies of phyllosphere microbial communities under stress.

Key words:Reaumuria trigyna;seasonal alternation;phyllosphere salt content;phyllosphere bacteria;phyllosphere fungi