Studying of chloroplast diversity in some apple genotypes from North-West of Iran in comparison of some Alborz genotypes, commercial cultivars and rootstocks

  Apple is one of the most important fruit products in temperate regions. The cultivation of this product has been done during a very long time in Iran and even according to some resources; Iran has been called as one of the hometowns of this plant. The most basic step in breeding programs for fruit trees is collecting and evaluating internal and external germplasm resources. Nowadays considering the importance of healthy eating and sustainable production of apple with higher quality, modifying apple trees, is essentially based on “resistance genes”. Given that most apple varieties are being propagated asexually, low genetic diversity is expected. But among genotypes that are the result of the upgrade, expected diversity increases because these genotypes are mostly seed progenies. In this study we have tried to evaluate the genetic diversity of organelles of some local genotypes of apple cultivated on the main cultivation areas in North West of Iran and Central Alborz and compare them with two commercial cultivars (Red Delicious and Fuji) and also M4 and M9. For this investigation, young, fully developed leaves were sampled, their DNA genomes were extracted. In order to evaluate organelles diversity, 30 apples, four pairs of specific primers for the chloroplast genome (K1K2, CS, HK and TF) and two restriction enzymes (EcoRI and MseI) in Cleaved Amplified Polymorphic Sequences (CAPS) method were used. NTSYS and POPGENE were used for data analysis. Among these four markers, three markers have the ability to amplify appropriately, in which 4.13% of apple chloroplast genomes were amplified. By haplotype examination of samples, a total of eight haplotypes were identified which among them, H4 was the largest group with 26.66 percent of the total samples. All this groupings have been created due to the occurrence of mutations and/or deletions. Mean of genetic variation within (HS), Total (HT) and degree of genetic differentiations (GST) were 0.4451, 0.467 and 0.0481, respectively. The results showed that there is no systematic genetic structure between samples of studied regions. These results also confirmed the possibility of applying Cleaved Amplified Polymorphic Sequences (CAPS) method to identify genotypes and varieties of apples. Using these markers, genetic diversity in organelle DNA was observed amongst apple genotypes, however, this variation was not able to separate the genotypes in different regions.
It seems perhaps by increasing the number of primers and restriction enzymes, this distinction can be achieved. The results of this study showed that native apple genotypes in Iran, posses high genetic diversity due to sexual reproduction in the past