Isolation and Properties of Deoxyribonucleic Acid from Protoplasts of Cell Suspension Cultures of Ammi visnaga and Carrot (Daucus carota).

A procedure is described for the isolation of native DNA from protoplasts of ammi (Ammi visnaga) and carrot (Daucus carota) cells. Protoplasts were produced from 40 grams of fresh cells by enzyme hydrolysis and lysed with sodium dodecyl sulfate. The DNA was purified by treatment with pronase and ribonuclease. Final isolation was achieved by sucrose density gradient centrifugation.The melting temperature of ammi and carrot DNA in 0.15 m NaCl and 15 mm trisodium citrate buffer, pH 7.0, was 84.0 C and 84.5 C, respectively. The molecular weight for ammi DNA was 1.43 x 10(8), and for carrot DNA it was 1.56 x 10(8). Ammi DNA exhibited a single band at 1.690 grams per cubic centimeter in CsCl, whereas carrot DNA showed two bands, one at 1.693 grams per cubic centimeter and another at 1.706 grams per cubic centimeter. Ammi DNA consisted of a doublestranded form, since denaturation of the DNA caused a complete upward shift of 0.020 grams per cubic centimeter.