tGall forming phylloxera may compete for nutrients with meristematic tissues and develop heterotrophicstructures that act as carbon sinks. In this work, we studied the underlying starch metabolism, sink-source translocation of soluble sugars towards and within root galls. We demonstrated that nodositiesstore carbohydrates by starch accumulation and monitored the expression of genes involved in the starchmetabolic. Thereby we proved that the nodosity is symplastically connected to the source tissues throughits development and that the starch metabolism is significantly affected to synthesize and degrade starchwithin the gall. Genes required for starch biosynthesis and degradation are up-regulated. Among the car-bohydrate transporters the expression of a glucose-6-phosphate translocater, one sucrose transporterand two SWEET proteins were increases, whereas hexose transporters, tonoplast monosaccharide trans-porter and Erd6-like sugar transporters were decreased. We found general evidence for plant responseto osmotic stress in the nodosity as previously suggested for gall induction processes. We concludethat nodosities are heterogenous plant organs that accumulate starch to serve as temporary storagestructure that is gradually withdrawn by phylloxera. Phylloxera transcriptionally reprograms gall tis-sues beyond primary metabolism and included downstream secondary processes, including response toosmotic stress.