Miscanthus × giganteus: Regeneration system with assessment of genetic and epigenetic stability in long-term in vitro culture

Species of Miscanthus Anderss., C4 perennial rhizomatous grasses with low input requirements, have become representative crops for lignocellulosic bioenergy and material resources in temperate climates. Most of the commercial cultivars appropriate for cropping within Europe and North America are based on Miscanthus × giganteus species. Because of their triploid hybrid nature, micropropagation of these species using in vitro cultures is a common method both of plant multiplication on a commercial scale and of long-term preservation of their valuable genotypes. The somaclonal variation that can occur during in vitro culture may be useful for strain improvement during plant breeding, but is undesirable for long-term genotype preservation; therefore, the genetic and epigenetic stability of regenerated plants needs to be assessed. The objectives of our study were (1) to develop an effective system for Miscanthus × giganteus plantlet production, starting from callus induction, and shoot and root regeneration, and ending with plant acclimatization; and (2) to evaluate any genetic and epigenetic instability induced by long periods of in vitro cultivation using ISSR, RAPD and MS-ISSR molecular markers on selected M. × giganteus clones. We present an efficient and stable method of M. × giganteus regeneration and preservation by long-term in vitro culture. Both morphological and molecular marker analyses revealed no major genetic or epigenetic changes among clonally propagated M. × giganteus that had been maintained by long-term shoot culture. However, when screening for genetic variation, particular attention should be paid to genomic regions associated with GACA, GATA, AG and CTC repeats.