The Use of Enzymes in the Preparation of Root-Tip Smears

A simple root-tip smear method for the study of somatic chromosomes of Allium is described, in which an aqueous solution of colchicine and Pectinol, (an enzyme preparation) is used. The root tips are placed in a 0.2% aqueous colchicine solution for 30 minutes, fixed in propionic-alcohol solution, run through a graded series of alcohols, washed thoroughly, treated with a 1% aqueous solution of Pectinol for 1 to 1 ½ hours, and allowed to stand in water 3 to S days to soften. A thin transverse section through the meristematic portion of the root tip is then smeared on a slide in a drop of propiono-carmine stain in the usual way and sealed.