Structure and function of transfer cells in the sporophyte haustorium of Funaria hygrometrica hedw: III. Translocation of assimilate into the attached sporophyte and along the seta of attached and excised sporophytes

Translocation of products of photosynthesis from gametophyte to sporophyte was examined in the moss Funaria hygrometrica Hedw., as an adjunct to companion studies on the ultrastructure of the sporophyte haustorium and its capacity for absorption of sugars in vitro. Labelled products derived from gametophytic photosynthesis are transported to the sporophyte at an approximately linear rate for up to 12 h after a pulse treatment with ¹⁴CO₂. Large sporophytes receive label at a greater rate than smaller ones. Transport is inhibited under conditions of water stress, and by lack of light, though darkening the sporophyte alone has no effect. Movement of label from the haustorium along the seta occurs at a velocity of 1-3 mm h^-1, and is similar to the onward movement of label derived from [³H]glucose supplied to the haustorium in vitro.