Biochemical Mechanisms of Resistance to Leaf Blight in Resistant Individual Trees of Platycladus orientalis

The leaf blight of Platycladus orientalis caused by Chloroscypha platycladus was found a severe disease in Jiangsu Province recent years.Several disease-resistant individuals were selected in heavily infected plantations.Biochemical substance concerned to disease resistance in selected resistant individual trees and common susceptible ones of Chinese arborvitae(P.orientalis) to leaf bilght was tested.It was found that lignin and cellulose content, phenylalanine ammonia-lyase (PAL) and superoxide dismutases (SOD) activities in the leaves of selected resistant individual trees were markedly higher than those of the common susceptible ones.It was also found that there was highly positive correlation between PAL activity and lignin content in leaves.Neverthless, water content and succelence in leaves of resistant trees were significantly lower than those of the susceptible ones.