Developmental Stage Shapes the Leaf-Associated Bacterial Community of Eugenia uniflora and Reveals Shared Bacterial Taxa with Other Myrtaceae Species

The phyllosphere microbiome contributes to plant health and adaptation, yet bacterial communities associated with Eugenia uniflora remain poorly characterized. This study investigated how developmental stage shapes the E. uniflora phyllosphere microbiome and assessed bacterial taxa and associations shared with other Myrtaceae species. The V3–V4 region of the 16S rRNA gene was sequenced from 19 E. uniflora samples representing young and mature trees, as well as 13 samples from mature trees representing three additional Myrtaceae genera (Myrcianthes, Plinia, and Psidium) and other Eugenia species. Community diversity, predicted functional potential, co-occurrence networks, and core taxa were analyzed. In E. uniflora, 1428 bacterial ASVs belonging to 17 phyla and 135 genera were identified, and bacterial community composition differed significantly between developmental stages. Young and mature trees showed distinct taxonomic profiles and predicted functional patterns. Network analysis revealed more connected bacterial communities in young plants and simpler networks in mature plants. Comparison with other Myrtaceae identified 17 core genera, including Methylobacterium–Methylorubrum, Hymenobacter, Sphingomonas, Bdellovibrio, and Terriglobus, which occurred in all 21 mature trees. Overall, developmental stage was associated with changes in the taxonomic, predicted functional potential, and network organization of the E. uniflora phyllosphere microbiome, while shared bacterial taxa and associations across the sampled Myrtaceae genera suggest conserved features of phyllosphere community assembly.