TY - JOUR T1 - Commensal bacteria act as a broad genetic buffer in <em>Drosophila</em> during chronic under-nutrition JF - bioRxiv DO - 10.1101/334342 SP - 334342 AU - Dali Ma AU - Maroun Bou-Sleiman AU - Pauline Joncour AU - Claire-Emmanuelle Indelicato AU - Michael Frochaux AU - Virginie Braman AU - Maria Litovchenko AU - Gilles Storelli AU - Bart Deplancke AU - François Leulier Y1 - 2018/01/01 UR - http://biorxiv.org/content/early/2018/05/30/334342.abstract N2 - Eukaryotic genomes encode several well-studied buffering mechanisms that robustly maintain invariant phenotypic outcome despite fluctuating environmental conditions. Here we show that the gut microbiota, represented by a single Drosophila facultative symbiont, Lactobacillus plantarum (LpWJL), acts also as a broad genetic buffer that masks the contribution of the cryptic genetic variations in the host under nutritional stress. During chronic under-nutrition, LpWJL consistently reduces variation in different host phenotypic traits and ensures robust organ patterning; LpWJL also decreases genotype-dependent expression variation, particularly for development-associated genes. We further demonstrate that LpWJL buffers via reactive oxygen species (ROS) signaling whose inhibition severely impairs microbiota-mediated phenotypic robustness. We thus identified an unexpected contribution of facultative symbionts to Drosophila fitness by assuring developmental robustness and phenotypic homogeneity in times of nutritional stress. ER -