Cryopreservation: an alternative for the long-term storage of old potato varieties

A simple freezing method has been developed for the cryopreservation of an in vitro collection of old potato varieties. More than 125 varieties or genotypes have been frozen and stored in liquid nitrogen. Most varieties have high survival rates, averaging 80%. Plant regeneration rates were lower and averaged 40%. Plants have been obtained from all varieties or genotypes frozen and the phenotypes of regrown plants matched very well those of the unfrozen stock plants. However, one plant was found which was probably polyploid and five plants had poor growth. In addition, the genetic stability of 161 regrown plants was checked by flow cytrometric measurements and DNA-fingerprinting. In the 161 tested samples neither polyploid plants nor unusual banding patterns were found.