An anatomical study on galls on Cryptomeria

Abstract

Ascocarps of a fungus were found on every gall on the branches and stems of Cryptomeria japonica D. DON from May to June. This fungus had been named Nitschkia tuberculifera KUSANO, however, features of the fungus were clearly different from the characteristics of the genus Nitschkia. Identification of the fungus should be pursued in detail. The fungal infection begins in the axil part of leaves of young green shoots. These Cryptomeria galls develop from hyperplasia of the infected tissue. Subsequently, meristematic cells induced by the hyphae are differentiated into parenchymatous cells and cambia. An uneven distribution of the hyphae results in the formation of a rough surface with many small papula around the infected part. The Cryptomeria gall has been classified as an organoid gall like witches' broom; however, the gall tissue is different from the healthy tissue of Cryptomeria shoots and has properties similar to those of callus tissue and other histoid galls.