Accumulation of phytoalexins in leaves of plane tree (Platanus spp.) expressing susceptibility or resistance to Ceratocystis fimbriata f. sp. platani

Inoculation of leaves of resistant Platanus occidentalis and susceptible Platanus acerifolia leaves with Ceratocystis fimbriata f. sp. platani, the canker stain disease agent, induced foliar necrosis and biosynthesis of two phytoalexins, scopoletin and umbelliferone. Foliar symptoms keep localized and accumulation of coumarin phytoalexins was rapid for incompatible interactions. Necrosis spread widely and accumulation of these phenolic compounds was much later and lower for compatible interactions. The differential response could be used in a genetic improvement program for resistance against canker stain.