Cryopreservation and Genetic Stability of Shoot Cultures in Vegetatively Propagated Species: Mint and Chrysanthemum

Cryopreservation allows long-term conservation, and the genetic stability of the preserved material is one of its most important features compared to other conservation techniques. However, this stability has been questioned and in some cases genetic instability after cryopreservation has been detected. Cryopreservation processes involve exposure to extreme physiological conditions, not only low temperature, but also osmotic and dehydration stresses, together with the use of substances potentially toxic and/or mutagenic, such as DMSO. In this work, we compare the results obtained in the analysis of the genetic stability of two vegetatively propagated crops after cryopreservation: mint (Mentha xpiperita) and chrysanthemum (Chrysanthemum xmorifolium). Genetic stability analyses were conducted with DNA molecular markers (RAPD and AFLP). Two cryopreservation techniques were compared for both species: encapsulation-dehydration and vitrification for chrysanthemum; and encapsulation-dehydration and droplet-vitrification for mint. In both cases, more instability was observed after the first protocol. In a study performed after each step of the encapsulation-dehydration protocol with chrysanthemum, such instability occurred after treatments where osmotic stress was imposed. In mint, the instability observed after cryopreservation by encapsulation-dehydration was influenced by the genotype but not by the recovery medium used. The results showed the importance of testing genetic stability of the recovered material and the implications of adopting one technique in comparison to others.