1972 Volume 41 Issue 3 Pages 245-249
It has been reported that arbutin is one of phenolic compounds in bark, leaf and fruit of Japanese pear, and hydrolyzed into hydroquinone and glucose by β-glucosidase. Six resistant and five susceptible varieties were used to determine the relationship between arbutin content and resistance to black spot disease of Japanese pear. As a result, there was no correlation between amount of arbutin content and resistance to black spot disease.
On relationship between leaf age and β-glucosidase activity, its activity was high in young leaf both resistant and susceptible varieties, but not in mature and old leaf in both. β-glucosidase activity was higher in resistant variety than susceptible one. And its activity of resistant variety in very young leaf was 2.3 times more than susceptible one.
By injecting with host-specific toxin produced by fungus into very young and young leaves both resistant and susceptible varieties, β-glucosidase activity was inhibited in susceptible variety, but its activity in resistant one was not.
It was considered that activity of β-glucosidase in resistant variety is one of the factors of resistance to black spot disease of Japanese pear.
