Monoclonal antibodies to a fern spermatozoid detect novel components of the mitotic and cytokinetic apparatus in higher plant cells

The aim of this study was to search for uncharacterized components of the plant cytoskeleton using monoclonal antibodies raised against spermatozoids of the fern Pteridium (Marcet al. 1988). The cellular distribution of crossreacting immunoreactive material during the division cycle in wheat root tip cells was determined by immunofluorescence microscopy and compared to the fluorescence pattern obtained with antitubulin. Five antibodies are of special interest. Pas1D3 and Pas5F4 detect a diffuse cytoplasmic material, which, during mitosis, follows the distribution of microtubules (MTs) at the nuclear surface and in the preprophase band (PPB), spindle and phragmoplast. The immunoreactive material codistributes specifically with MT arrays of the mitotic apparatus and does not associate with interphase cortical MTs. Pas5D8 is relevant to the PPB and spatial control of cytokinesis. It binds in a thin layer at the cytoplasmic surface throughout the cell cycle, except when its coverage is transiently interrupted by an exclusion zone at the PPB site and later at the same site when the phragmoplast fuses with the parental cell wall. Pas2G6 reacts with a component of basal bodies and the flagellar band in the Pteridium spermatozoid and recognizes irregularly shaped cytoplasmic vesicles in wheat cells. During interphase these particles form a cortical network. Pas6D7 binds to dictyosomes and dictyosome vesicles. At anaphase the vesicles accumulate at the equator and subsequently condense into the cell plate.