Evidence for proteins specific for vascular elements in intact and cultured tissues and cells of maize

A group of antigenically distinct proteins characteristic for the tissue complex of the vascular cylinders was found in maize (Zea mays L.) seedlings using an immunofiltration technique. Specific stelar antigens present in the fully developed stele (vascular cylinder) of the primary root were also found in steles extracted from adventitious roots and from the mesocotyl but were absent, within the limits of sensitivity of the immunodiffusion tests employed, in root cortex and epidermis. Some of the stelar antigens were also evident in the meristem of the primary root and were present in traces in the scutellum, the mesocotyl node, and the primary leaves plus coleoptile. The specific stelar antigens could be traced in 13- and 15-day-old developing embryos and were definitely expressed by the 21 st day after pollination. Several stelar-specific antigens were found in embryo-derived callus tissues and in stem-derived cells maintained in serial suspension culture. Higher resolution of the stelar antigens by a modified technique of crossed immunoelectrophoresis was used to demonstrate several minor stelar antigens that were presumably characteristic exclusively of the completely differentiated stele. This technique along with sequential immunoprecipitation of labelled proteins provided a semiquantitative estimate of the specific stelar antigens in the meristem and the stele of the primary root, and in suspension-cultured cells which were devoid of noticeable signs of vascular differentiation.