Abstract
In order to clarify biochemical natures of the resistance on the chestnuts tree to chestnut gall wasp, polyphenolic substances were estimated as compared with the resistant wild Japanese chestnuts and the susceptible ones. Furthermore, contents in the barks of both current year shoots were determined every month. The results obtained were summarized as follows:
1) In wild Japanese chestnuts similarly in the cultural varieties, catechol tannins and leucoanthocyanidins are abundant, but pyrogallol tannins are a little in the resistant varieties.
2) Total tannins decrease accordnig to ageing and the amount of decrease from June to August in the resistant trees are less than of the susceptible.
3) Catechol tannins are poor within the current year shoots are young, but increase their content with maturing the tissues, and trend are most remarkable increase during the period from middle or late June to early August, that is, from before the laying eggs of chestnut gall wasp through the period of hatching to the gall formation. The resistant varieties contain more catechol tannins every time than the susceptible ones, and are more active in biosynthesis.
4) As for leucoanthocyanidins, the same inclination with catechol tannins was observed.
5) Pyrogallol tannins contain more in the susceptible trees and in immature tissues, and decrease seasonaly, and their decrement is greater in the resistant.
