Somaclonal variation in olive (Olea europaea L.) plants regenerated via somatic embryogenesis: Influence of genotype and culture age on genetic stability

The objective of this work was to investigate the influence of the genotype and culture age on the genetic stability of olive (Olea europaea L.) plants regenerated by somatic embryogenesis. Plants derived from eight embryogenic lines maintained by repetitive subculture for two (T lines) and eight years (P lines) were analyzed using RAPD and SSR markers. In our work, RAPD markers resulted more informative than SSR markers, but both techniques were valuable for the identification of somaclonal variation in olive somatic embryogenesis-derived plants. Both molecular markers detected intraclonal variation in both age groups, showing a slightly higher variability in the older lines. Lines T2 and T4 resulted completely stable with RAPD and SSR, although one of the youngest lines (Ti) showed the lowest similarity coefficients also with the two types of markers. In conclusion, although variation was slightly higher in plants derived from lines maintained in vitro for a longer time, genetic instability seems to be mainly genotype dependent, thus confirming the results previously obtained by Bradai et al. (2016b) when assessing the same plants by phenotypic analysis.