Combination of morphological and molecular markers for the characterization of ancient native olive accessions in Central-Eastern Tunisia

Abstract

Increasing olive germplasm erosion in the coastline of Tunisia has required an imperious conservation of the traditional genotypes before an ultimate disappearance. This region has been relatively neglected in the literature sources of olive identification. In this context, a prospection effort and a preliminary selection of olive accessions belonging to Central-Eastern Tunisia was carried out. Twenty-seven ancient olive accessions were studied by combining molecular and morphological data in order to fingerprint them, and to evaluate their relationships with classical cultivars. Compared to known classic Tunisian olive cultivars, the new prospected olive accessions were well distinguished, presenting a potential use as promising genotypes. The morphological and molecular data showed a high diversity between genotypes. 92 and 63 polymorphic bands were scored using 10 RAPD and 9 SSR markers, respectively. Significant correlation coefficients were obtained among fruit and stone sizes (r=0.90) and among their shapes (r=0.73). The genetic distances obtained with the two DNA marker systems were significantly correlated (r=0.45) according to Mantel's test. No significant correlation was observed between distances based on molecular and morphological markers. UPGMA analysis based on molecular data showed no clear clustering trends according to morphological traits or fruit use. Despite the high genetic variation among accessions in each prospected area, geographical origin seemed to have significant impact on the observed variability. The relationship between morphological and molecular data has confirmed that each marker expressed different aspects of variability. Integration between all markers will be useful for distinguishing new accessions and genotyping local varieties.

Chemical Characterization of Oleaster, Olea europaea var. sylvestris (Mill.) Lehr., Oils from Different Locations of Northeast Portugal

“…For the remaining parameters (presence of nipple, number of lenticules, colour when the fruit reaches the definitive colour when mature) similar ranges were found among the three studied populations (Table 1). Concerning the morphological parameters of the endocarp, the stone weight significantly varied from 0.32 g (Alijó location) to 0.20 g (VNFC location) (p-value < 0.0001), similar to the lower results reported by [27] for ancient native olive accessions in Central-Eastern Tunisia populations (i.e., 0.15-1.23 g, for endocarps) and 3.5-6.0 times lower than the weights usually reported for the endocarps of cultivated olive cultivars of the same Portuguese region [26]. Among the three populations, the lowest values for endocarp length, width and shape were obtained in the VNFC population, being consistently and significantly higher in the Alijó population (p-value < 0.0001).…”

“…The tocopherol profile was similarly to that of olive oil, with α-tocopherol representing more than 90% of the total tocopherol content [33]. The amounts quantified in the present work were much higher than those observed for oleaster oil from Algeria, which varied from 87 to 182 mg/kg of oil [7] and Turkey, with values lower than 40 mg/kg of oil [34] but were of the same order of magnitude of those reported by Baccouri [27], for seven populations from Tunisia (309.5-781.8 mg/kg of oil); and by Dabbou [12] that analysed two Tunisian samples and reported α-tocopherol contents of 313-390 mg/kg of oil.…”

Varietal identification in olive tree (Olea europaea L.) by morphological and biometric characterization of fruits and stones of Algerian cultivars

“…In this study, the MCA analysis showed that the shape of the fruit, weight and shape of the stone in addition to the position of its maximal transversal diameter as well as its -cation. Similarly, our results of PCA also corroborate those of Laaribi et al (2017) and Dridi et al (2018), showing that the weight of the olive and the stone are positively correlated and were the most discriminating quantitative characteristics compared to the other biometric parameters of these parts while the number of grooves remains the least discriminating. Moreover, several studies demonstrated the superiority of the discriminative power of the characteristics of the endocarp (Barranco, 1994).…”

“…Moreover, several studies demonstrated the superiority of the discriminative power of the characteristics of the endocarp (Barranco, 1994). In our case, the contribution of the characters of the fruit and the stone were very close with a slight superiority for those of the fruit with 50.8 and by Cantini et al (1999) and Laaribi et al (2017), emphasizing the importance of fruit traits for the recognition of olive cultivars. However, the use of pomological characters alone may lead to incomplete differentiation results (Hannachi et al, 2008).…”

Genetic Resources of Olea europaea L. in the Garda Trentino Olive Groves Revealed by Ancient Trees Genotyping and Parentage Analysis of Drupe Embryos

“…DNA genotyping by microsatellite markers or simple sequence repeats (SSRs) is the most suitable method for olive genetic variability studies [ 18 , 26 , 27 , 28 ]. A different set of markers, tested in true-to-type reference material, have been proposed as standard lists to be used for olive cultivar identification [ 29 , 30 , 31 , 32 ], being those within the consensus list of 11 loci proposed by Baldoni et al [ 30 ] for olive genotyping the most used [ 6 , 7 , 8 , 13 , 21 , 28 , 33 , 34 ]. Moreover, the molecular and morphological characterization of the two Worldwide Olive Germplasm Banks (WOGB) of Córdoba [ 31 ] and Morocco [ 32 , 33 ] provided an important tool for scientists, nurseries and breeders.…”