Radioactive Tracer Study of Sporophyte Nutrition in Hepatics

Abstract

Sporophytes of Fossombronia foveolata, Lophocolea heterophylla, Pellia epiphylla, Ptilidium pulcherrimum, and Riella affinis were surgically isolated from host gametophyte tissues and treated with 14CO2. Sporophytes of all five species are capable of fixing CO2 in the light. Sporophyte/gametophyte ratios for 14CO2 fixation/mg fresh weight range between 0.12 and 0.39. Corresponding ratios for chlorophyll content are 1.07 to 3.30. Of the total 14CO2 fixed by excised Lophocolea sporophytes, 40% can be attributed to the photosynthetic activity of haploid spores. Enveloping gametophytic tissues (calyptra and pseudoperianth) inhibit photosynthesis of attached sporophytes by as much as 50%. For sustained growth, sporophytes rely on organic nutrients supplied by the gametophyte: radioactivity of Lophocolea sporophytes increases significantly after application of 14C‐glucose to host gametophytes. Surgically isolated sporophytes develop slowly in mineral culture, without significant increase in dry weight. The assumption that hepatic sporophytes are at least partly autonomous with respect to organic nutrition (an assumption that figures prominently in speculation on the evolutionary origin of the sporophyte) is confirmed.

Transport of carbon and phosphorus compounds about Sphagnum

“…In Polytrichum, transport occurs to underground axes as well as to apices (Collins & Oechel 1974)? and there is evidence of transport from gametophyte to sporophyte in several cases (Proctor 1977(Proctor , 1982Thomas et al 1979). There is one report (Skre et al 1983) of basipetal transport in S. subsecundum labelled in the field with 14C in C02.…”

Mixed evolutionary traits of Tolypella (section Rothia, Charales) compared with Chara and Nitella shown by ultrastructure of vegetative internodal cells

“…There are also elaborate, localized cell wall ingrowths in the cell walls of the non-Charalean charophyte Coleochaete orbicularis, present in cells adjacent to developing zygotes during the stage of reserve material accumulation (Graham and Wilcox, 1983;Graham and Kaneko, 1991). Similar structures have also been found in placental transfer cells of bryophytes, where labyrinth cell walls are well developed in cells of the gametophyte in contact with the sporophyte, where the transfer of solutes from gametophyte to sporophyte is documented (Kelley, 1969;Browning and Gunning, 1979;Thomas et al, 1979). Labyrinth wall projections have also been widely described for transfer cells in angiosperms and gymnosperms (Pate and Gunning, 1972;Schmidt and Bartels, 1996).…”