The continuous culture of excised potato roots

Summary The establishment of potato root cultures from 1 mm root tips was achieved on a modified White§ medium containing tuber extract, casein hydrolysate and 2,4‐dichlorophenoxyacetic acid. This medium has allowed the continuous culture of roots for at least 10 successive passages over a period of about 10 months. Roots grown on an agar‐solidified medIUm were thick and clothed with root hairs, although they elongated more slowly than those grown in a liquid medium. The latter were thm and delicate. In Murashige and Skoog§ medium, supplemented with kinetin (0.2 p.p.m.) + dichlorophenoxyacetic acid (0.2 p.p.m.) or Naphthalaneacetic acid (0.2 p.p.m.) + Yeast extract (1000 p.p.m.), nodule‐like structures developed on the roots. If maintained under high light intensities, the roots and nodules had a tendency to turn green but the formation of laterals was inhibited.