Determination of Genetic Diversity of Walnut (Juglans regia L.) Genotypes Grown in Khorasan Province Using RAPD, ISSR and SSR Markers

Walnut (Juglans regia L.) is an important nut and timber tree species belonging to the family Juglandaceae. Iran ranks among the leading walnut-producing countries in the world, after the United States and China. Persian walnut is widely cultivated for its high-quality nuts and valuable wood. Due to its predominant seed propagation and outcrossing nature, walnut exhibits considerable genetic diversity, which can be exploited in breeding programs for crop improvement. In the present study, genetic variability, and relationships among ۱۳ promising walnut genotypes were evaluated at the Khorasan Razavi Agricultural and Natural Resources Research Center using three molecular marker systems: RAPD, ISSR, and SSR. Among the ۱۵ RAPD, ۱۰ ISSR, and ۱۵ SSR primers tested, ۸ RAPD, ۳ ISSR, and ۶ SSR primers produced clear, reproducible, and scorable bands with a high level of polymorphism. RAPD, ISSR, and SSR primers generated a total of ۹۳ amplification products, of which ۷۶ were polymorphic. Genetic similarity based on RAPD, ISSR, and SSR markers ranged from ۰.۴۳۱ to ۰.۷۵۴, with a mean value of ۰.۵۹۲. A relatively moderate to high level of genetic diversity was observed between the Z۳۰ and Ronde De Montignac genotypes. SSR analysis revealed ۵ to ۷ alleles per locus, all of which were polymorphic, while genetic similarity values ranged from ۰.۱۲۳ to ۰.۵۷۱ with an average of ۰.۳۴۷. Cluster analysis grouped all accessions into two major clusters with several subclusters, indicating considerable genetic variation among the studied genotypes. These findings provide useful information for walnut germplasm characterization, conservation, and future breeding programs.

کلیدواژه ها:

Genetic diversity ، Juglans regia ، Molecular markers ، polymorphism ، Walnut