show Abstracthide AbstractPedunculate oak (Quercus robur L.), an important forest tree in temperate ecosystems, displays an endogenous rhythmic growth pattern, characterized by alternating shoot and root growth flushes paralleled by oscillations in carbon allocation to below- and aboveground tissue. This common plant trait so far has largely been neglected as a determining factor for the outcome of plant biotic interactions. This study investigated the transcriptomic response of oak to migratory root-parasitic nematodes Pratylenchus penetrans in relation to rhythmic growth, and how this plant-nematode interaction is modulated by an ectomycorrhizal symbiont Piloderma croceum. This work was part of the research program TrophinOak (www.trophinoak.de) of seven research groups working with oak microcuttings to study gene expression and resource allocation in multitrophic interactions, funded by the DFG, German Research Foundation.