Developmental regulation of the maize Zm-g60.1 gene encoding a beta-glucosidase located to plastids

A beta-glucosidase that cleaves the biologically inactive hormone conjugate s cytokinin-O- and kinetin-N3-glucosides is encoded by the maize Zm-p60.1 g ene. The expression of the Zm-p60.1 gene was analyzed by Northern blot anal ysis and in-situ hybridization. It was found that the expression levels of the Zm-p60.1-specific mRNA changed after pollination of carpellate inflores cences. The Zm-p60.1 cDNA was expressed in E. coli and antibodies were rais ed against this protein. An antibody was used to determine the tissue-speci fic localization of this protein. By in situ immunolocalization experiments , this protein was found to be located in cell layers below the epidermis a nd around the vascular bundles of the coleoptile. In the primary leaf, the Zm-p60.1 protein was detected in cells of the outermost cell layer and arou nd the vascular tissue. In floral tissue, Zm-p60.1 was present in the glume s, the carpels and in the outer cell layer of the style. In coleoptiles, as determined by immuno-electronmicroscopy, the Zm-p60.1 protein was located exclusively in the plastids.