Abstract: The expansion of excised cucumber cotyledons was induced by the treatment of 10 ppm of 6-benzyladenine (6-BA) in dark. The elongation and division of cells in this cotyledon are related to the activation of microtubules. The cDNAs of α- and β-tubulin from mouse and Physarum polycephalurn were used as probes to detect the transcriptional regulation of tubulin genes in the expanding cotyledons treated with 6-BA. The expression of mbulin genes has also Lcen analyzed at the translational level by Western blot and ELISA with antibody against tubulin purified from chicken brain. The results showed that genes encoding two subunits of tubulin in excised cucumber cotyledons were rapidly activated by cytokinin 6-BA at both transcriptional and translational levels. It implied that tubulin increasement was involvedin the cytokinin-induced expansion of excised cucumber cotyledons.

Key words: Cytokinin, Tubulin, Cucumber cotyledon, Gene expression