CHANGES IN ENZYMES AND PROTEINS IN SALT-SHOCKED VS. GRADIENT INCREASES IN NACL IN `POINSETT' CUCUMBER ROOTS
Cucumis sativus, L., `Poinsett' seedlings were grown under artificial light in 40% modified Hoagland's solution until an average plant plastochron index of 4.73 was reached. Plants were then placed in solutions of (1) 0 mM NaCl, (2) 80 mM NaCl (salt-shock), or (3) placed in a dropwise gradient solution of NaCl and Hoagland's until the final concentration of 80 mM NaCl was reached at 41 hours. Leaves of the 80 mM shock treatment wilted immediately, but recovered turgor within 6 hours. Leaves of 80 mM gradient did not wilt at anytime. The control and gradient treatments had relative growth rates which were similar to each other, but RGR decreased in the shock treatment. Invertase activity was measured in the roots at 24, 41, and 48 hours after initial treatment. Invertase activity of shock treatment increased significantly over the controls at 24 hours. The 80mM gradient was not significantly different than either treatment. Four isozymes of α– galactosidase were detected. The relative intensities of the bands varied with time and treatment. One invertase band was resolved in roots on 8% native acrylamide gels. SDS gels indicated increases in proteins in the gradient treatment compared to the control and the 80 mM shock treatment.