BAINBRIDGE, TROY*, KEVIN CURRAN, SARAH SHAW, AND DARLENE SOUTHWORTH. Department of Biology, Southern Oregon University. - Antibodies to Brassica sperm recognize diverse cell types and gametes.
Little is known about the mechanism of fusion of plant gametes during
reproduction. Studies on reproduction in animals suggest that fusion
of sperm and egg includes protein recognition. We raised monoclonal
antibodies against purified Brassica rapa sperm cells to
visualize membrane proteins. Three antibodies (BRSP1, 2, 3) bound to
B. rapa protoplasts isolated from stem, root, and leaf tissues
indicating that the epitopes to these monoclonals were not specific to
sperm cells. The molecular weight of the epitope to BRSP1 was 54 kDa,
and it was not glycosylated. Antibodies also recognized gametes of
other angiosperm species (Arabidopsis, Eruca,
Lilium, Plumbago, Nicotiana) and a fern
(Ceratopteris), and gametes of a green alga
(Acetabularia). However, the molecular weight of these epitopes
varied. None of the antibodies to B. rapa sperm prevented
fertilization in assays with Ceratopteris richardii or with
Acetabularia acetabulum indicating that these particular
protein epitopes may not be associated with gamete fusion. Funded by
NSF-RUI grant IBN-9816945.
Key words: antibodies, Brassica, fertilization, gametes, sperm