Physiological and biochemical changes in resistant and sensitive chestnut (Castanea) plantlets after inoculation with Phytophthora cinnamomi

Different changes in physiological and biochemical parameters were observed between resistant and sensitive chestnut plantlets upon inoculation with the ink disease pathogen Phytophthora cinnamomi. Infection led to shoot death in 87.5% of the sensitive plants (cv. Judia) in 30 days, while all resistant plants (Ca90, hybrid C. crenata × C. sativa progeny) survived. Judia plants exhibited a decrease of 92.9% in leaf water potential 16 days after infection, while in Ca90 plants the decrease was only 35.8%. After infection, the photosynthetic rate of Judia plants decreased significantly by 58.3%. A significant increase in the level of total phenols (50%) was observed in the leaves in infected Ca90 plants; whereas in sensitive Judia plants, no difference in phenol content was observed upon the oomycete infection. Infection also resulted in an increase in soluble sugars and a decrease in starch content in the resistant genotype. These results provided new insights into the mechanisms of resistance to chestnut ink disease.

► Total phenols content was higher in resistant than sensitive clones.
► The necrosis of inoculated plants grew more and faster in sensitive clones.
► After 35 days all resistant clones remained alive.