Identification of genetic diversity among Juglans regia L. genotypes using molecular, morphological, and fatty acid data

In this study, 40 walnut (Juglans regia L.) samples including international cultivars, national cultivars and local genotypes were analyzed in terms of detailed morphological traits, molecular characteristics, and biochemical (fatty acids) features. The results showed high morphological diversity among the genotypes, and the kernel ratio was found to have major contribution for the principal component analysis (PCA). Molecular results showed that the 19 SRAP primer combinations produced, on average, 171 bands in the accessions examined, of which 156 (90.6%) were polymorphic and DICE's similarity coefficient ranged from 0.49 to 0.94 indicating high genetic diversity. The polymorphism ratio of 11 primers was 100% while the lowest polymorphism was 66.7%. There were no significant differences in terms of correlation coefficient between the similarity matrices of the morphological traits and SRAP (r = 0.03). The main fatty acids of walnut kernel oils were found to be linoleic acid (C-18:2) followed by oleic acid (C-18:1) and linolenic acid (C-18:3). The polyunsaturated fatty acids constitute the main group of fatty acids in walnut kernel oils, and these ratios varied between 85.99-92.19%. It has been determined that the morphological and biochemical data may be insufficient alone in identification of genetic diversity and relativeness in walnut because they should be supported by molecular data.

Automated summary

The study revealed high genetic diversity in walnuts, primarily driven by the kernel ratio. Molecular analysis showed a significant amount of polymorphism in the SRAP primer combinations, indicating high genetic diversity in walnuts. Additionally, walnut kernel oils consist mainly of linoleic acid, with polyunsaturated fatty acids being the predominant fatty acid group.