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

Ink disease caused by the root-rot pathogen P. cinnamomi (Pc) threatens European sweet chestnut (Castanea sativa Mill.) orchards, and growers increasingly graft susceptible C. traditional varieties on Pc-resistant hybrid commercial rootstocks. The influence of scion, rootstock, grafting per se vegetative budburst, growth, susceptibility to Pc defence-related hormone profile Castanea spp. are unknown. In a greenhouse experiment, these effects were evaluated reciprocally two resistant crenata x clones clones. Resistance content leaves roots rootstock-dependent, survival rates chestnuts strongly increased when grafted scion had no effect resistance trees, but influenced budburst primary growth. Grafting altered phytohormone especially in rootstocks, did not growth trees. Grafting-induced alteration constitutive defense-related could explain rootstocks Pc. Nine days after infection, dynamic hormonal response consisting decreased jasmonates (JA JA-Ile) ABA JA-Ile was observed chestnuts. This is first study addressing role modulating soil-borne