A Root Tip Squash Technique for Soybean Chromosomes¹

Abstract

A procedure is described for consistently obtaining adequatenumbers of well‐spread metaphase cells from soybean [ Glycine max (L.) Merr.] root tips. The salient features are: (i) seeds germinated at alternating temperatures of 30 C for 18 hours and 22 C for 6 hours until roots are 7 to 10 cm long; ii) pretreatment of root tips in saturated paradichlorobenzene at 15 C for 1½ to 2 hours; and iii) fixation in 3:1 for 48 hours at 37 C before hydrolysis and staining in leuco‐basic fuchsin. Tips were incubated in pectinase for 1½ hours at 30 C, and the cells were flattened with a pellet press.