Surface charge density estimation of vigna mungo protoplasts using a fluorescent dye, 9-aminoacridine

We showed that the surface charge density of protoplasts can be estimated by the 9-aminoacridine method. The estimated surface charge density of the protoplasts isolated from elongating regions of Vigna mungo root was - 39 ± 8 mC/m². The negative surface charge density increased when protoplasts were treated with glutaraldehyde or when EDTA was added to the protoplast suspension medium. These results support the validity of our estimation of the surface charge density of protoplasts by the 9-aminoacridine method. The concentration of amino groups at the surface of the protoplasts was estimated to be 34 mC/m².