Somaclonal variation induced by adventitious shoot regeneration in pear and apple

Somaclonal variability was studied in regenerants of apple and of pear by RAPD analysis. Adventitious shoot regeneration was obtained using leaves or vegetative shoot apices as explants and satisfactory morphogenic response was obtained with both systems, but with the apex explants the regeneration percentages and also the number of shoots per explants were higher than with the leaves. Histological studies revealed that all the regenerated shoots from apices originated from callus, while in the leaf explants the first vegetative buds regenerated directly from leaf tissue, whereas buds that appeared later on regenerated from callus. Thirty regenerants of each species, obtained with the two regeneration inducing methods, were screened using twenty IO-mer primers. The analysis revealed some polymorphisms in regenerated clones obtained through the leaf regeneration method, while none was detected in regenerants obtained from vegetative shoot apices. The work shows the potential for using RAPD analysis to study somaclonal variability in pear and to confirm it in apple. It revealed genetic differences among regenerants obtained in these species through adventitious shoot regeneration from leaf explants.