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

• The genotype has a fundamental effect determining somaclonal variation in olive somatic plants.
• Prolonged culture proliferation time significantly increased the proportion of somaclonal variants.
• Chimerism was observed in olive plants regenerated via somatic embryogenesis.
• Variant plants displaying shortening of the juvenile period were obtained via somatic embryogenesis.

The objective of the present investigation was to evaluate the effect of the genotype and culture age on appearance of somaclonal variation in olive plants regenerated via somatic embryogenesis. For this purpose, plants were produced from 8 embryogenic lines maintained by repetitive subcultures in ECO medium for different time periods. Four and a half years after acclimatization, plants were phenotypically evaluated by morphological and biometric analysis of vegetative and reproductive characters and compared with control plants derived from seeds. The results obtained revealed the existence of somaclonal variation in olive plants regenerated via somatic embryogenesis. Fourteen variant phenotypes were identified affecting plant vegetative and reproductive development. Biometric analysis also showed the existence of intraclonal variation in quantitative traits related to plant architecture. The genotype was a fundamental factor in the appearance of somaclonal variation, with some lines especially susceptible to change. Higher variation was in general observed in plants derived from aged lines, although this effect was strongly influenced by the embryogenic line. Variants exhibiting shortening of the juvenile period obtained in the present investigation can constitute a very interesting material to be included in olive breeding programs nowadays in progress.

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