Use of ISSR markers for assessing genetic diversity of apple ( Malus x domestica ) cultivars growing in Morocco

Genetic diversity of 29 apple ( Malus domestica ) cultivars collected from different regions in Morocco was investigated using inter-simple sequence repeat (ISSR) markers. 15 ISSR primers generated 177 bands of which 156 are polymorphic (86.50%). The mean value of PIC, Rp, I and H were 0.46, 4.58, 0.43 and 0.28, respectively, implying important genetic variability between the studied apple cultivars. Furthermore, the coefficient of genetic differentiation among all groups was 0.27, indicating that 27% of total genetic variability was between groups and 73% was within groups. Bayesian analysis grouped the studied cultivars into three major clusters that are not in agreement, in major part, with their geographic origin and did not show any difference between local and introduced cultivars. Also the problem of synonyms, homonyms, and/or labeling errors appears in the studied cultivars. These results showed that the ISSR markers can be a useful tool for detecting the genetic diversity in this fruit crop.