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

Micropropagated strawberry plants (Fragaria x ananssa L.) grown on 5 mu M a nd 15 mu M BA medium or cold-stored were grown in the field to examine morp hological variation. Except for plant height. morphological characteristics did not differ for field-grown plants micropropagated on 5 mu M and 15 mu M BA medium. Cold-stored plants were less vigorous, buth vegetatively and r eproductively, than BA-treated plants. Random amplified polymorphic DNA (RA PD) markers were used to determine if cold storage or supraoptirnal levels of N-6-benzyladenine (BA) in the culture metlinm caused genetic changes lea ding to somaclonal variation. No mutations were observed in 246 loci amplif ied by the 29 primers tested. Possible changes in methylation patterns of r ibosomal DNA genes of strawberries were also examined. Changes in methylati on 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 explant. The low le vels of RAPD variation and methylation observed, and the apparently epigene tic changes in morphological characteristics in plants used in this study, indicated that mutations had not occurred.