Receptacle regeneration in Sargassum muticum (Phaeophyta)

Abstract Receptacle regeneration in the adventive marine brown alga Sargassum muticum (Yendo) Fensholt (Fucales, Phaeophyta) is examined using light and electron microscopical (SEM, TEM) techniques and laboratory culture studies. After transverse bisection, receptacle regeneration occurred under a wide range of temperatures and at different daylengths but was inhibited under winter conditions (10°C, 8:16 h). Regeneration is a particularly rapid process with mature, zygote-bearing receptacles formed at the cut surface within 21 d at 20°C, 16: 8 h and 88 μmol photons m−2 s−1. Cytological and morphogenetic changes observed after wounding include: the breaking of intercellular plasmodesmatal connections; retraction of cytoplasm and deposition of new fibrillar material beneath the exposed degenerating cell walls, preventing cytoplasmic loss; the formation of a protective wound epidermis over the entire cortical wound surface by finite mitoses in the outermost cell layer; concurrent mitoses to a depth of at lea...