Effect of grafting on phenology, susceptibility to Phytophthora cinnamomi and hormone profile of chestnut

•Grafting did not influence vegetative budburst and growth of chestnut trees.•Grafting increased the susceptibility to Pc of resistant rootstocks.•Grafting altered the defense-related hormone content in resistant rootstocks.•Hormonal changes triggered by grafting and Pc infection were described.•The hormone profile and resistance to Pc in chestnut were rootstock-dependent.