Root Border Cells as Tools in Plant Cell Studies

Perhaps the most important feature of using border cells to study cellular interactions is that, unlike other plant cells, they can be collected nondestructively. No tissue is torn, excised, digested, or homogenized to procure these cell populations. Although the same can be said for cell suspension cultures, border cells provide several important advantages over cultured cells: 1. Unlike suspension cultures, which consist primarily of large, nonuniform cell clumps, border cells compose populations of separated cells and/or small monolayer clusters of cells. This allows uniform exposure of cells to assay conditions, and greatly facilitates light or scanning microscopic observation of cellular responses (Hawes and Wheeler, 1982; Sherwood, 1987). 2. Border cells are taken directly from the plant in their normal developmental state, and are not exposed to the drastic physiological and genetic disturbances inherent with cell suspensions grown in liquid culture for weeks, months, or years. 3. Within families that produce border cells, experiments are not confined to those species or genotypes that happen to grow well in culture or are available in cell suspension. Border cells to be used in assays can be collected from seedlings of any genotype of interest, including mutants or individual transgenic roots (Nicoll et al., submitted). 4. No special equipment or facilities are required to obtain populations of border cells for assays, so protocols are accessible to anyone with a microscope and a supply of seeds.