Inhibition of Zeatin-Induced Growth of Cucumber Cotyledons by Sulfite Ions

摘要

The inhibitory effects of sulfite ions on zeatin-induced cell expansion in cotyledons excised from dark-grown seedlings of cucumber (Cucumis sativusL.) were examined. With 50μM zeatin the growth rate in white light was about twice that of the control. Addition of Na2SO3in the growth medium inhibited the zeatin-induced growth of cotyledons. Zeatin-treatment increased the osmotic potential in cell sap of cotyledons, while sulfite decreased it. These treatments had no significant effect on potassium concentration. Sulfite inhibited the zeatin-induced increase in contents of fructose and glucose, but did not affect sucrose content. The relative contents of non-cellulosic constituents of cell walls fell with the advance of culture. This decrease was repressed by sulfite, indicating that inhibition of expansion growth in cucumber cotyledons by sulfite ions was the result of alterations in the cell wall structure due to changes in the cell wall metabolism