Gametophyte culture in vitro and antheridiogen activity in Blechnum spicant

Growth of Blechnum spicant gametophytes was optimal in MS liquid medium, a 16-h photoperiod, and it was unaffected by variation of the pH between 4.7 and 8.7. Antheridia were observed during all developmental stages of the gametophyte: filamentous, spatulate or cordate and their formation was induced by compounds excreted into the culture medium by mature gametophytes. This antheridiogen activity was found in the fractions corresponding to free and apolar esters of gibberellins. IBA at 5 micromolar and 50 micromolar, and BA at 50 micromolar inhibited antheridiogen. Exogenous application of GA3 allowed spore germination but strongly inhibited gametophyte development; the two dimensional state was not reached.