Protoplast regeneration from normal and bromodeoxyuridine-resistant sycamore callus

Abstract
Protoplasts have been prepared from normal and mutant lines of sycamore callus, maize root and tobacco leaf. Fusion was rare in sodium nitrate solutions. A mutant tissue culture was selected for by its resistance to 10 µg/ml bromodeoxyuridine. The mutant is sensitive to the Hypoxanthine-Aminopterin-Thymidine (HAT) selective medium but has normal thymidine transport and thymidine kinase activity.