Morphological and molecular analysis of genetic stability in micropropagated Fragaria x ananassa cv. pocahontas

Micropropagated strawberry plants (Fragaria x ananassa L.) grown on 5 μ M and$15 \mu M BA$medium or cold-stored were grown in the field to examine morphological variation. Except for plant height, morphological characteristics did not differ for field-grown plants micropropagated on 5 μ M and$15 \mu M BA$medium. Cold-stored plants were less vigorous, both vegetatively and reproductively, than BA-treated plants. Random amplified polymorphic DNA (RAPD) markers were used to determine if cold storage or supraoptimal levels of$N^6-benzyladenine$(B A) in the culture medium caused genetic changes leading to somaclonal variation. No mutations were observed in 246 loci amplified by the 29 primers tested. Possible changes in methylation patterns of ribosomal DNA genes of strawberries were also examined. Changes in methylation patterns were observed in only one DNA sample from plants grown on$15 \mu M BA$medium and in one of the cold-stored plants. Length polymorphism was observed in two samples from plantlets derived from one expiant. The low levels of RAPD variation and methylation observed, and the apparently epigenetic changes in morphological characteristics in plants used in this study, indicated that mutations had not occurred.