MOLECULAR-STABILITY OF THE RIBOSOMAL-RNA GENES IN SOLANUM-TUBEROSUM PLANTS RECOVERED FROM SLOW GROWTH AND CRYOPRESERVATION

Ribosomal gene (rDNA) probes have been used to assess genomic changes in plants of (1) S. tuberosum cv Desiree subjected to slow growth and (2) S. tuberosum cv Golden Wonder recovered from cryopreservation. Restriction fragment length polymorphisms (RFLPs) were detected in two out of 16 DNA samples extracted from plants derived from slow growth, control plants did not show RFLP differences. Plants recovered from cryopreserved shoot-tips of Golden Wonder were unchanged in their ribosomal gene RFLP profile compared to the untreated controls. The use of rDNA probes as tools to assess stability, and the possible detrimental effects of slow growth, somaclonal variation, cryoprotectants, and freezing injury are discussed.