Diversity Assessment of Algerian Wild and Cultivated Olives (Olea europeae L.) by Molecular, Morphological, and Chemical Traits

Abstract

Algeria has several genetic resources on olive trees, mainly made up of small indigenous cultivars, and a very important wild heritage. Twenty olive samples including eight cultivars and twelve wild trees from the province of Bejaia (Algeria) are characterized, by combining molecular data (13 SSRs), fruit and pit morphological traits, fatty acids composition, and phenolic compounds of the extra virgin olive oils (EVOOs). The genetic results based on PCoA, UPGMA, and AMOVA analyses demonstrate that olive cultivars and wild trees are mixed, suggesting kinship relationships between cultivated and wild olive trees and even cases of synonymy between some cultivars. PCA analysis on morphological traits shows a good separation of the two olive botanical varieties, the wild olive trees producing smaller fruits than those of the cultivated ones. Significant differences are also found in terms of fatty acids and phenol compounds composition of the EVOOs. Wild olive oils show the highest contents on phenolic compounds, mainly oleocanthal, as well as a considerable richness on oleic acid. The comparison of pairwise distances between olive trees obtained by genetic, morphological, fatty acids and phenolic compounds contents data using Mantel's test indicates a significant correlation among morphological characteristics, DNA polymorphism, and phenolic compounds. The results obtained in the present work contribute to reveal the diversity existing in the cultivated and wild olive trees of the region of Bejaia, shedding some light on the importance of Algerian olives germplasm.Practical Applications: Cultivated and wild olive diversity are assessed by genetic, morphological, fatty acids and phenolic composition. SSR marker analysis demonstrates the presence of a high genetic variation between the analyzed samples. A significant correlation of morphological characteristics with DNA polymorphism and phenolic compounds is found. A significant diversity in the wild and cultivated olive trees is observed.Kinship relationships between wild and cultivated Algerian olive trees are demonstrated using SSR markers, while the morphological parameters allow a good distinction between the two taxa. Significant differences are found for fatty acids and phenol compounds composition for the EVOOs; the wild olive oils present an interesting composition compared to the cultivated form.