• CCD
• resistance
• pathosystem
• Cupressus sempervirens
• Seiridium cardinale
• cypress

Common cypress (Cupressus sempervirens L.) represents one of the major features of the Italian landscape. However, several diseases affect this species among which the Cypress Canker Disease (CCD), caused by the invasive necrotrophic fungus Seiridium cardinale (Wagener) Sutton et Gibson. One of the most promising method to limit the CCD is the cypress breeding program that has already patented a series of canker-resistant clones of C. sempervirens. The aim of this study is to characterize the resistance mechanisms in terms of hormones and antioxidants in the bark and foliage of ramets of susceptible and resistant C. sempervirens clones artificially inoculated with S. cardinale. Ramets of both clones were stem-inoculated with S. cardinale at bark level and then samples were collected before the inoculation at 0 days (‘uninoculated’) and after 1, 3, 4, 6, 9 and 13 days post inoculation (dpi) at bark and foliage level. Fresh tissues were used for ethylene determination, while the remaining material was used for the evaluation of jasmonic, salicylic and abscisic acids content, hydrogen peroxide’s levels, oxidative damage and antioxidant activity. The two-way analysis of variance was used to investigate the effect of “clone”, “time” and their interaction. In inoculated susceptible cypress, a high production of ethylene and jasmonic acid occurred at 3 and 4 dpi in the bark (more than 2-fold higher than uninoculated ones). However, in the foliage a partial redox rearrangement of antioxidant capacity was recorded. In inoculated resistant cypress, an increased biosynthesis of ethylene was observed at 3 and 13 dpi in the bark (more than 2-fold higher). Conversely, a rise of salicylic acid levels (more than 2-fold) occurred at 1 dpi in the foliage, concomitantly to an accumulation of abscisic acid, that reached the maximum values at 9 dpi. The early activation of phytohormones and signaling molecules may counteract oxidative burst and prevent lipid peroxidation by offering protection to bark tissues and foliage in resistant cypress.