Comparative Studies of Leaf Tissue 4

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Abstract
Commercially available cell wall-degrading enzymes frequently used for protoplast isolation inhibited CO2 fixation and photosynthetic O2 evolution, and stimulated dark respiration by leaf tissue and isolated mesophyll protoplasts of Nicotiana tabacum L. and Antirrhinum majus L. They also depolarized the membrane potential of cells of leaf tissue, inhibited uptake of 86Rb by tobacco leaf tissue and isolated mesophyll protoplasts, and stimulated 36CI uptake by tobacco leaf tissue. Where studied, these effects were found to be reversible. The depolarization effect on Antirrhinum leaf cells occurred even when the enzyme preparations had been denatured, dialysed, or desalted, and the effect was greatest in those fractions of the enzyme preparation which showed the highest cellulase activity. Plasmolysis of tobacco leaf tissue inhibited photosynthetic O2 evolution, CO2 fixation, and 86Rb uptake to levels below those exhibited by isolated protoplasts in media of the same composition and osmolarity. The implications of these results for work with leaf tissue and isolated protoplasts are discussed.