Membranous film on the developing apothecium ofSclerotinia sclerotiorumand its relationship to ascospore discharge

摘要

A membranous film (MF) covers the hymenium of the ascocarp ofSclerotinia sclerotiorum(Lib.) de Bary. The MF is reported for the first time using a scanning electron microscope. Development of the MF is described in relation to the morphogenesis of apothecia. At the early stage the MF develops centripetally from the edge of the hymenium adjoining the rim of the ascocarp. At the beginning of the intermediate stage, the surface of the hymenium is fully covered by the MF which has many small holes and a few fenestrations. The MF is thin and smooth at the center but thick and wavy near the margin of the ascocarpic disc. Since the MF ruptures at or just before the massive ascospore discharge which occurs at the intermediate stage, it may protect the developing asci from loss of moisture before the initial spore discharge.