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 mu M and 50 mu M, and BA at 50 mu M inhibited antheridiogen. Exogenous application of GA(3) allowed spore germination but strongly inhibited gametophyte development; the two dimensional state was not reached.