|PEREDO, ELENA - UNIVERSIDAD DE OVIEDO
|ARROYO-GARCIA, ROSA - DEPARTAMENTO DE BIO.
|REVILLA, M. ANGELES - UNIVERSIDAD DE OVIEDO
Submitted to: Cryobiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/14/2008
Publication Date: 9/11/2008
Citation: Peredo, E.L., Arroyo-Garcia, R., Reed, B.M., Revilla, M. 2008. Genetic and Epigenetic Stability of Cryopreserved and Cold-Stored Hops. Cryobiology.57(2008)234-241.
Interpretive Summary: The genetic resources of hops are preserved as field plants and backed up for safety as tissue cultures in cold storage, or as cryopreserved shoot tips. This study was to determine genetic changes that might occur with these procedures. Three hops cultivars were analyzed for genetic change after tissue culture, cold (45 °F) storage, and cryopreservation in liquid nitrogen (-320 °F). Most of the variation noted could be related to the cold storage or cryopreservation protocols. Variations of 8 to 20% were noted for the hop cultivars. The pattern of change could be explained by temporary changes related to the cold acclimation step present in both treatments. Cold acclimation is a complex process, achieved by short day length and low temperatures, which results in the reprogramming of metabolism and gene expression. We can assume that those treatments had at least some effects on the genes. The amount of variation detected is similar for cold-stored (2.6 to 8.6%) or cryopreserved (2.6 to 9.8%) hops. Similar changes were reported in cryopreserved apple and strawberries and citrus callus under slow growth conditions. Cold acclimation was not used prior the storage protocols for any of these studies.
Technical Abstract: Standard cold storage and cryopreservation methods for hops (Humulus lupulus L.) are available but, to our knowledge, the genetic and epigenetic stability of the recovered plants were never tested. This study analyzed 51 accessions with two molecular techniques, Random Amplified DNA Polymorphism (RAPD) and Amplified Fragment Length Polymorphism (AFLP), and no genetic variation among control and treated plants was found. Epigenetic stability was evaluated using Methylation Sensitive Amplification Polymorphism (MSAP), and over 36% of polymorphic loci were detected in the accessions analysed. The major part of the changes were demethylation events and they were shared by the cryopreserved and cold stored plants indicating a possible effect of the cold acclimation process present in both protocols. The remainder of the polymorphisms were protocol specific.