Propagule-Specific Bacteriome of Funneliformis mosseae Spores and Hyphae: Integrated High-Throughput and Culture-Dependent Insights.

Abstract

Arbuscular mycorrhizal (AM) symbiosis is increasingly recognized as a tripartite interaction involving the fungal symbiont, the host plant, and a diverse assemblage of associated bacteria. Through this study, propagule-specific bacteriome of Funneliformis mosseae was explored, particularly its taxonomic composition and plant growth-promoting (PGP) potential. Using a polyphasic approach integrating Illumina high-throughput sequencing with culture-dependent techniques, bacterial communities associated with monosporal hyphae and spores were characterized. Sequencing analyses revealed distinct taxonomic profiles between two propagule types: spores were dominated by Pseudomonas, whereas hyphae harbored higher relative abundances of Sphingobium and Rhodococcus. Culture-dependent screening on NBRIP medium yielded 53 phosphate-solubilizing bacterial isolates-21 from spores and 32 from hyphae. While hyphae-associated propagules contained a greater number of phosphate-solubilizing isolates, those from spores exhibited significantly higher solubilization capacities, ranging from 16.87 to 273 µg mL⁻¹, with 47.6% exceeding 100 µg mL⁻¹. In contrast, hyphae-derived isolates ranged from 35.03 to 142.20 µg mL⁻¹, with 28.1% surpassing the 100-µg mL⁻¹ threshold. Functional screening further revealed that 38% of spore and 31% of hyphae-associated isolates exhibited diverse PGP traits. The five most potent strains were identified through 16S rDNA sequencing as Pseudomonas aeruginosa, Lactiplantibacillus plantarum, Bacillus haynesii, Bacillus licheniformis, and Enterococcus innesii. This study represents the first attempt to characterize a propagule-specific core bacteriome in Funneliformis mosseae, revealing clear taxonomic and functional divergence between spore and hyphae-associated bacterial communities. These findings highlight the specialized ecological roles of distinct propagule microbiomes and offer novel avenues for targeted manipulation of AM symbiosis to enhance plant nutrient acquisition and growth.