ACTIN IN THE DEVELOPING STOMATAL COMPLEX OF WINTER RYE - A COMPARISON OF ACTIN ANTIBODIES AND RH-PHALLOIDIN LABELING OF CONTROL AND CB-TREATED TISSUES

Actin localization during stomatal complex formation in rye leaf epidermis was compared by three different labeling procedures. When leaf segments are fixed with formaldehyde prior to staining, microfilament (MF) patterns visualized with actin antibodies and those with rhodamine-phalloidin (Rh-ph) are basically identical in controls. Likewise, on tissues treated with cytochalasin B (CB), actin antibodies and Rh-ph produce very similar labeling patterns. Compared to MF alignments in fixed samples, additional sets of MFs are observed at the very cortical regions of epidermal cells that are stained with Rh-ph without aldehyde fixation. Cortical MFs are also present in a variety of mitotic cells; MFs of meristematic cells and guard mother cells are more concentrated near the walls facing spindle poles, whereas a fine meshwork of MFs is observed along the entire periclinal surface of subsidiary mother cells. Although exactly how MFs are involved in control of the division site in higher plant cells is still to be determined, the presence of MFs during mitosis and the abnormal division observed in some stomatal cells after treatment with CB suggest that MFs are necessary for normal orientation of division in these cells, and thus normal morphogenesis.