Genetic and epigenetic fidelity of garlic cryopreserved plant material compared to field collections

• Garlic accessions may show different degree of genetic diversity. • A genebank garlic accession is composed of different genotypes. • Epi-genetic data of ex situ conserved accessions and their origin is essential. Garlic ( Allium sativum L.) is an important bulb vegetable of culinary and medicinal use. It is propagated vegetatively, and its plant genetic resources must be, therefore, conserved either in field collections, under in vitro culture conditions, or cryopreserved. The different conservation methods have their advantages and disadvantages, but all of them must secure the genetic fidelity of the samples. Within the genetic stability concept, the epigenetic stability of stored germplasm is of increasing concern as epigenetic changes may affect gene expression resulting in phenotypical changes. In this study, we compare plant material from field collections and from in vitro plants recovered after cryopreservation of two garlic accessions using genetic and epigenetic markers. Markers used for the genetic stability analysis were: Random Amplified Polymorphic DNA (RAPD), an arbitrary molecular marker, and Simple Sequence Repeat (SSR), a specific marker. RAPD markers were obtained from 11 different primers, and the SSR markers from 10 microsatellite loci . For the epigenetic analysis, Methylation Sensitive Amplified Polymorphism (MSAP) markers were used. Although the initial genetic composition of both accessions was very different, they showed a substantial genetic stability. RAPD markers only detected differences in one sample from the field collection from one accession, while samples from the second one were monomorphic. However, SSR markers revealed differences between field and cryopreserved samples for both accessions. The MSAP analysis showed a higher DNA methylation level in the cryopreserved samples than those from the field collection. The implications for germplasm conservation are discussed.