PERITHECIUM DEVELOPMENT IN CHAETOMIUM TRIGONOSPORUM

Abstract

Chaetomium trigonosporum produces mature perithecia and a Scopulariopsis-like conidial state in cultures derived from single ascospores. The perithecial primordium consists of a central ascogonium surrounded by a vegetative sheath. Division and tangential growth of the peridial cells results in enlargement of the perithecium and the development of a central cavity. The ascogonium initial which typically arises from a single uninucleate cell of the vegetative mycelium soon develops into an ascogonium consisting of several uninucleate cells. Several cells of the ascogonium become multinucleate. From these cells the ascogenous hyphae branch more or less dichotomously toward the apex of the perithecium. The cells of the ascogenous hyphae are uninucleate and apical cells develop into asci directly, without the crozier stage.C. trigonosporum has a "Xylaria type" centrum characteristic of Chaetomium and distinct from the "Ophiostoma type" centrum found in Microascus.