Structural variability and functional association in the epiphytic bacteria assemblies of freshwater macrophytes (Myriophyllum spicatum)

The underlying principles influencing bacteria community assembly have long been of interest in the field of microbial ecology. Environmental heterogeneity is believed to be important in controlling the uniqueness and variability of communities. However, little is known about the influence of the host macrophytes on epiphytic bacteria assembly processe. Here, we produced two contrasting artificial water environments (eutrophic and oligotrophic) for reciprocal transplant experiment of Myriophyllum spicatum , to recover the colonization of epiphytic bacteria accompanied with plants growth. Comparative analysis addressed a higher species diversity in epiphytic bacteria than in bacterioplankton, and the highest microbiome richness in sediment. Our data revealed that the organization of epiphytic bacterial community was interfered by both plant status (i.e. branch number, net photosynthesis rate etc.) and water bodies (i.e. total phosphate, total nitrogen, pH etc.) while plant status effected the assembly in priority to water. 16S rRNA sequencing further indicated that the epiphytic assemblies were motivated by functionalization and interplay with hosts as a whole. The results complemented new evidences for the ‘lottery process’ in the epiphytic bacteria assembly traits and shed insights into the assembly patterns referring to functional adaptation across epiphytic bacteria and macrophytes. Importance A robust understanding of inter-adaptation between microbiome and the host plants have been established basing on vast majority of researches. However, great efforts were made mostly on rhizosphere microbiome. By contrast, referring to another representative group, macrophytes who composed of the freshwater ecosystem were relatively less investigated on such issue. Our study pioneered the experimental operation to interrogate the triadic relationship among macrophytes, epiphytic bacteria and water body. The research present here showed significant exemplar on discussion of plant associate bacteria adaptation taking account of host colonization as well as the epiphytes. The results expand the hypotheses of bacteria assembly principle and provides potential leads on understanding of plant - microbe interactions.