The long-term conservation of potato genetic resources can effectively
be achieved by cryopreserving shoot-tips in liquid nitrogen. This in
vitro storage procedure is convenient for vegetatively propagated crop
s. it is important, in establishing these procedures, that the genetic
stability of the regenerating plants be identical to the initial star
ting material. Molecular studies have shown the main ribosomal RNA gen
e fragments to be reproducible hybridisation signals between individua
l plants, whereas other hybridisation signals derived from a 2.55kb DN
A fragment were notably variable. The significance of these results fo
r in vitro conservation is discussed.