Studies of the human microbiome have shown that a person’s genome plays an important role in determining the composition of the microorganisms that cohabitate the body. But what about trees? A team led by Wout Boerjan of Ghent University and Jaco Vangronsveld of Hasselt University decided to find out by studying whether poplars genetically modified to produce less lignin—facilitating their use in biobased chemical and energy production—have microbiomes similar to their wild-type counterparts. When the researchers compared stem, root, and leaf microbiomes of GMO poplars, they found that the trees recruited different species of microorganisms and a higher total number of microbial cohabitants (Proc. Natl. Acad. Sci. USA 2016, DOI: 10.1073/pnas.1523264113). Interrupting lignin biosynthesis—just with the silencing of a single gene—led to the accumulation of different phenolic compounds in the xylem of the modified trees. The researchers propose that the different phenolic menu is partly responsible for recruiting different bacteria. They caution that new metabolites produced by altered microbiomes could interfere with the intended phenotype of GMO plants. Unraveling these genotype-microbiome interactions may provide crucial clues for improving applications of genetic engineering in agriculture and phytoremediation, the team says.