Molecular and genome size analyses of somaclonal variation in apple rootstocks Malling 7 and Malling 9

摘要

The cultivated apple (Malus domestica) is important fruit crops cultivated inworld. For production and breeding of high quality apple, inducing and enhancing new geneticdiversity and suitable traits are necessary. In Iran, different local and imported apple genotypesare cultivated and common apple root stocks (Malling 7) M7 and (Malling 9) M9 are mostly usedroot stocks in the country. Therefore, we studied genetic diversity of M7 an M9 tissue cultureregenerated plants produced by different treatments by using twenty ISSR markers. In total51 randomly selected plants were studied for the occurrence of somaclonal variation in applemother plants and tissue culture regenerated plants. Four different treatments were used fortissue culture. Genetic diversity parameters, genetic distance and polymorphism percentagewere studied in regenerated plants. Variations in loci frequency and combination were checkedby STRUCTURE and the presence of similar loci in the plants was studied by reticulation NJ tree.Genetic relationship versus distinctness was determined by principal coordinate analysis. Theresults showed the occurrence of genetic variation among mother plants and tissue culture regeneratedplants of each subculture due to somaclonal variation. Significant difference in thegenome size among some of the regenerated plants indicates that change in genetic structureof plants during tissue culture is also accompanied with quantitative change in DNA. However,degree of genetic variation differed among apple rootstocks and also among different treatmentsused.