Annals of Botany 80: 197-204, 1997
© 1997 Annals of Botany Company
The Identification of an Anther Specific Antigen inBrassicaSpecies using a Heterologous Monoclonal Antibody
School of Botany, University of Melbourne, Grattan Street, Parkville, Victoria, 3052, Australia
Received December 19, 1995 ; Accepted March 21, 1997 .
Monoclonal antibody, MAb 69-139-19, raised against sheep sperm, cross-reacted with anther proteins from fourBrassicaspecies tested. Early in anther development the MAb weakly detected a polypeptide of
42 kDa. At the mid-maturation stage the MAb still bound weakly to this band but it also detected a polydisperse band of Mr 160–230 kDa. In mature pollen MAb 69-139-19 labelled the polydisperse region of 160–230 kDa very strongly, as well as a faint, but distinct, band of116 kDa. Immunogold labelling ofB. napusL. anthers and pollen grains also showed a differential pattern of labelling. At the early vacuolate stage the MAb recognized an antigen within the tapetum and the microspore cytoplasm and nucleus. During the late vacuolate stage the MAb bound to the tapetal material during transfer to the pollen grain wall, leading to strong labelling of the pollen wall at maturity. In sheep MAb 69-139-19 binds to the postacrosomal region of the sperm (Hou, 1989). The polypeptide present in plants, which contains the epitope recognized by the MAb is likely to be a different protein to that in sheep, but we suggest that it plays a role in sexual reproduction inBrassica. It is possible that as the polypeptide is located in the pollen coat it may be involved in pollen/stigma interactions during pollination leading to successful adhesion and pollen tube germination.
Brassica napusL; incongruity; pollen-stigma recognition; pollination; rapeseed; heterologous antibody