Notes on the Development of the Gametophyte of Equisetum arvense in Sterile Media

Abstract

1. Gametophytes of Equisetum arvense L. may be cultivated aseptically on synthetic media from spores obtained from strobili previously subjected to the "aerosol-hypochlorite" sterilization treatment. 2. Aseptic suspensions of spores as well as spores still retained within the sporangia of the strobili following sterilization may be stored in Moore's solution at 5⚬ C. for a period of 3 months. The percentage of viable spores, however, becomes reduced with time. 3. Germination begins in 2-3 days on all suitable media in light. The period over which germination extends is shortened by the addition of sucrose or casein hydrolysate supplying fixed carbon and fixed nitrogen either separately or in combination. 4. Thalli develop normally on Moore's solution agar but more rapidly with added low concentrations of casein hydrolysate (50-100 mg/l) and with a low concentration of sucrose (5000 mg/l) or with combinations of these two substances. 5. Antheridia appear on the gametophytes early in the third week and archegonia presumably a little later, as the production of sporophytes begins usually in the fifth week of growth. 6. Browning and necrosis of the thalli appear eventually in cultures on all media and are hastened by crowding of the thalli, by enrichment of the media, and by higher concentrations of the enriching materials. These effects are related either to the exhaustion of some essential constituent of the medium or to the accumulation of metabolites that become toxic at some critical concentration. 7. By frequent transfer to fresh medium gametophyte cultures may be maintained in an active vegetative condition for indefinite periods. Cultures from spore sowings made in April, 1949, have continued vigorous to the present time, although they have produced no sex organs since the first 6 months of their growth.