Epigenetic Basis of Somaclonal Variation

Epigenetic changes induced in in vitro culture affect gene expression in a more or less permanent way, and in some cases are transmitted to the progeny. These changes affect chromatin structure and include changes in DNA methylation, histone modifications and the expression of small RNAs involved in DNA methylation (RNA-directed DNA methylation; RdDM). DNA methylation is one of the best studied epigenetic marks in regenerated plants, and changes in the methylation pattern have been reported to be the cause of somaclonal variation in many species. This chapter reviews the epigenetic basis of somaclonal variation and the tools used to detect it.