GREER, GARY K.* and DORTHY CURRY. Department of Biology, West Virginia State College, Institute, WV 25112-1000. - Pheromonal interactions among cordate gametophytes of the lady fern, Athyrium filix-femina.
Pheromonal interactions between cordate gametophytes of the lady fern,
Athyrium filix-femina, were investigated using a protocol typically
used for detecting water-soluble pheromones such as antheridiogen.
Three week-old, cordate gametophytes were transferred to agar
containing abstracts from a previous generation of gametophytes
(treatment) and to fresh nutrient agar (control). Three weeks after
transfer, gametophytes were examined from treatment and control
plates. Each gametophyte was measured for size (area) and shape
(circularity), and scored for number of antheridia and archegonia.
Treatment gametophytes were significantly smaller, less circular, had
fewer archegonia, and possessed antheridia more often, than control
gametophytes, a pattern consistent with known antheridiogen effects on
gametophytes of transitional morphology and sensitivity. The
experiment was repeated using gametophytes that were six weeks old at
time of transfer. Treatment gametophytes in the second experiment did
not differ in size, but were significantly more circular and possessed
fewer archegonia, than control gametophytes. The second experiment
revealed phytochemical interactions between cordate gametophytes. The
contradictory effects of increased circularity without increased size
may be due to one or more phytochemicals that accelerate anticlinal
divisions in the meristem resulting in increasing circularity, at the
expense of oblique or periclinal divisions that contributed to size.
Likewise, the decreased production of archegonia, which can not be
attributed to production of antheridia, may be a consequence of a
reduced rate of oblique and periclinal divisions in the meristem, from
which archegonia are ultimately derived. Antheridiogen, a
water-soluble pheromone with structural affinity to gibberellins and
that induces maleness in acordate gametophytes may be involved, since
its production is closely associated with attainment of a cordate
Key words: development, fern gametophyte, pheromone