Effect of antioxidants on the genetic stability of cryopreserved mint shoot tips by encapsulation-dehydration

The effect of antioxidants applied in one step of a cryopreservation protocol by encapsulation?dehydration on recovery and genetic stability of mint shoot tips has been studied. Glutathione (0.16 or 0.24 mM), ascorbic acid (0.28 or 0.43 mM) and ?-tocopherol (vitamin E) were added to the preculture medium (0.3 M sucrose). DNA was extracted from three different types of samples: leaves from shoots, callus at the base of shoots and callus. RAPD and AFLP markers were used to assess the genetic stability. The use of antioxidants did not improve recovery after cryopreservation. One of the genotypes, ?MEN 198?, showed higher percentage of stable samples than the other one, ?MEN 186? (56 vs. 37 %; considering all treatments and types of explant). The use of vitamin E improved the percentage of stable samples with respect to control treatment (no antioxidant) in ?MEN 186?. No differences in the percentages of stable samples were observed among cryopreserved and non-cryopreserved (treated similarly without immersion in liquid nitrogen) plant material. Recovered shoots of both genotypes showed higher stability (76?80 % stable samples) than callus samples (14?22 %).