The aerial surface of plants, known as the phyllosphere, makes up an estimated 108 km2 of the terrestrial microbial environment on the globe. Agricultural crops constitute much of that surface area, and so microorganisms that inhabit crop leaf surfaces are important players on the phyllosphere global landscape. Here, we characterize the assembly, diversity, and seasonal dynamics of bacterial and archaeal communities of the phyllosphere and associated soil of two perennial cellulosic feedstocks targeted for biofuel production - switchgrass (Panicum virgatum L.) and miscanthus (Miscanthus x giganteus). We used 16S rRNA gene sequencing and bacterial isolation to assess phytobiome diversity and structure.
Results/Conclusions
Miscanthus and switchgrass leaves harbored relatively simple bacterial communities of fewer than 100 taxa. They had a core microbiome of taxa that were both persistent and abundant, including several Proteobacteria lineages. We also observed late-season host specificity for some core members, though closely related taxa resided on both crops, suggesting functional redundancy. Core microbiome members were persistent over the growing season with directional changes in relative abundances, exhibited host specificity, and were very rare in associated soils. Thus, these core taxa likely are adapted for life on the leaf surface, rather than vagabonds that randomly assemble from air or soil. Surprisingly, there was no influence of fertilization on the phyllosphere phytobiome. Together, our results provide insights into key phytobiome members of cellulosic biofuel feedstocks and the drivers of their dynamics. This information provides an important step toward managing these phytobiomes to support crop wellness and productivity.