On the polyphenolic substances in the chestnut trees and the relation of the contents of them to the resistance to chestnut gall wasps

Abstract

The determination of polyphenolic substances in the Japanese and Chinese chestnut barks of current year shoots were made quantitatively and qualitatively by paper chromatography, colorimetry and other methods to elucidate the phenolic pattern among the species and varieties. Furthermore, the authors investigated the relation of the polypheno lic contents to the resistance to chestnut gall wasps which gave much trouble in chestnut culture.
1. The phenolics detected in chestnut barks are as follows; gallic acid, leucocyanidins, flavonol, ellagic acid, gallocatechin, catechol tannin, pyrogallol tannins and coumarin derivatives.
2. The Japanese chestnuts contain more catechol tannins (about 10-20mg/g. on the basis of dry weight) than Chinese ones (5mg/g. or so). High content of pyrogallol tannins was found in both the bark of them. Furthermore, of Chinese chestnuts, the southern varieties contain more of less water soluble fractions of pyrogallol tannins than the nor-thern ones.
3. In the resistant varieties to chestnut gall wasps, catechol tannins are high but pyrogallol tannins are relatively low in content. The correlation coefficients between the tolerance for chestnut gall wasps and catechol tannin contents and pyrogallol tannin contents are +0.782 and -0.476, respectively. The catechol tannin contents of resistant and susceptible varieties in one gram dry matter are 10.3 to 22.4mg and 2.7 to 16.2mg., respectively. Pyrogallol tannin content of resistant varieties varies 70 to 110mg., and of susceptible ones, 90-120mg.