Fig. 1. Three alkaline agarose gels showing DNA of unirradiated pea seedling leaves resulting from different isolation procedures. A. Lanes 1 and 2, Trial Procedure I (phenol, NaClO₄); Lanes 3 and 4, Trial Procedure II (phenol; chloroform:isoamyl alcohol); Lanes 5 and 6, Trial Procedure III (potassium acetate); Lane 7, Trial Procedure IV (phenol:chloroform:isoamyl alcohol, isopropanol precipitation); Lane 8, Trial Procedure V (phenol:chloroform:isoamyl alcohol, ethanol precipitation). B. Lane 9, protoplast production. C. Lane 10, agarose plug preparation. Panels A, B, and C are independent gels; the panels are aligned at the positions of the (48.5 kb) and T7 (39.9 kb) markers. In panel A, Lanes 3 and 4, as well as 7, 8, and M are longer (photographic) exposures of the same gel, since DNA in these lanes was very faint. Marker (M) lanes in gels A and B contained (48.5 kb) and T7 (39.9 kb) DNAs, as well as a HindIII digest of (23.1, 9.4, 6.6, 4.4, 2.3, 2 and 0.56 kb); the marker lane on Gel C also contained T4 DNA (170 kb)