Proteins reacting with cadherin and catenin antibodies are present in maize showing tissue-, domain-, and development-specific associations with endoplasmic-reticulum membranes and actin microfilaments in root cells

With heterologous antibodies raised against animal N-cadherin, alpha-cateni n, and beta-catenin, we have visualized their reactive proteins within cell s of maize root apices. Embedding using Steedman's wax allowed us to accomp lish tissue-specific analysis which revealed that cells of epidermis, endod ermis/pericycle, and outer stele tissues, all of which are tightly associat ed to each other, are especially enriched with presumed plant homologues of N-cadherin and both catenins. In the root epidermis, trichoblasts initiati ng root hairs showed prominent accumulations of cadherin-like antigens at o utgrowing domains where they co-localize with actin. Close associations of cadherin-like proteins with F-actin were detected in parenchymatic cells of the stele, also at the immunogold electron microscopy level. A possible ro le of these interesting proteins in membrane-membrane interactions is indic ated by their prominent accumulations at endoplasmic-reticulum-enriched pit -field-based plant cell adhesion domains in plasmolyzing cells of maize roo t apices exposed to mannitol. Intriguingly, these unique adhesion domains o f plasmolyzing cells are enriched with endoplasmic-reticulum-resident calre ticulin. Cadherin-like, but not catenin-like, proteins were abundant also w ithin the nucleoplasm.