Response of Leaf Endophytic Bacteria in Gypsophila paniculata L. Tissue Culture Seedlings to Polyethylene Glycol Stress

Purpose To study the effects of polyethylene glycol (PEG) stress on the diversity of leaf endophytic bacteria in Gypsophila paniculata L. tissue culture seedlings, providing theoretical basis for improving plant resistance to osmotic stress by improving plant microbiome.

Methods The tissue culture seedlings of G. paniculata were used as research materials, different mass fractions of PEG-6000 (0%, 5%, 20%) were used for stress treatment of the seedlings first, and then the structure and composition of the leaf endophytic bacteria community were investigated by 16S rDNA amplicon sequencing.

Results A total of 705 operational taxonomic units were detected from the samples of the seedlings, which were belong to 35 phyla, 59 classes, 115 orders, 183 families, and 238 genera. Axillary buds of G. paniculata had a high capacity to transfer the phyllosphere bacteria and maintain microbial diversity. The effect of 5% PEG on the leaf endophytic bacteria diversity was not significant; the bacterial diversity under 20% PEG stress was significantly reduced, and the co-occurrence network of the bacterial was also severely disrupted. After PEG stress, the relative abundance of Proteobacteria increased obviously, while the relative abundance of Firmicutes decreased obviously.

Conclusion Low mass fraction PEG stress will intensify the competition between bacterial communities, while high mass fraction PEG stress will significantly reduce the diversity of leaf endophytic bacteria community.