XVI International Botanical Congess

Mechanisms by which sperm recognize and fuse with the egg and central cell during double fertilization are unknown. To identify membrane surface molecules that might function in fertilization, we immunized mice with isolated sperm of Brassica campestris and screened polyclonal sera and monoclonal hybridoma supernatants via immunocytochemistry for binding to isolated sperm. We identified three cell lines producing hybridoma supernatants that bound to sperm cell surfaces in B. campestris and analyzed the properties of one. The molecular weight of the epitope was 43 kD, and was not glycosylated. The antibody recognized sperm of Plumbago, Nicotiana, Arabidopsis, and Eruca, and generative cells of Lilium and Narcissus, but did not recognize sperm of Helianthus, Gerbera or Zea. Antibodies to plant sperm allow us to probe sperm membranes for functional components. Funded by NSF-RUI grant IBN-9418178.