Genetic diversity of on-farm selected olive trees in Moroccan traditional olive orchards

Abstract

Selecting desired agronomic traits may lead to a loss of genetic diversity in crop species. A molecular investigation was conducted to determine how well a set of olive (Olea europaea L.) accessions sampled in Moroccan traditional orchards represented the entire Moroccan olive diversity range. We therefore collected, in traditional agroecosystems from northern and central Morocco, a total of 88 olive trees chosen for their agronomic traits based on local farmers' knowledge. Using 12 SSR loci, 45 trees (51.1%) had a genotype identical to the 'Picholine Marocaine' variety, while the remaining samples were classified into 27 different SSR profiles. Two categories of genotypes were identified: (i) genotypes closely related to the 'Picholine Marocaine' variety and probably resulting from intensive vegetative propagation from a limited number of clones, and (ii) genotypes displaying a high number of dissimilar alleles which may have originated from selected spontaneous seedlings. A significant difference in allelic richness was revealed between the 28 on-farm selected genotypes and the overall olive diversity, represented by 57 local genotypes, indicating that the on-farm selected trees represented a subsample of Moroccan genetic diversity. This could be explained by the prevalence of 'Picholine Marocaine' in traditional orchards, while some original genotypes with favourable agronomic traits resulting from local farmers' selection were also identified. Applying an ethnobotany approach combined with criteria to fulfil farmers' household needs could be particularly relevant and better explain the obtained results.

Olive Tree (Olea europaea L.) Diversity in Traditional Small Farms of Ficalho, Portugal

“…So, it probably resulted from a clonal mutation, although without phenotypic expression. Clonal variation in traditional olive varieties has been referred to in other studies [38]. Small genetic differences, probably due to somatic point mutations, were also reported in ancient olive trees [39] regardless of whether the phenotype was expressed [12].…”

“…It is recognized nowadays that on farm conservation is an important strategy of crop genetic resource conservation [38,44]. All over the Mediterranean region, traditional agroecosystems are of great importance as incubators of crop diversity [32,45,46] and as ecological infrastructures in general, providing essential ecological services.…”

Study of the behavior of cultivars from a world collection of olive (Olea spp.) in Morocco

“…The result of clonal selection in INRA, two varieties have been registered in the official catalog (Haouzia and Menara) and are currently massively propagated within the program "Green Morocco" (Khadari et al, 2016). In a parallel to the dominance of the variety Picholine Moroccan, an important diversity of genotypes cultivated locally was potentially recoverable (Khadari et al, 2008; El Bakkali et al, 2013). Until now, the INRA Morocco has not a representative collection of the local genetic diversity of all the traditional agrosystems (Khadari et al, 2008).…”

“…Until now, the INRA Morocco has not a representative collection of the local genetic diversity of all the traditional agrosystems (Khadari et al, 2008). The only ones of olive trees stemming from prospecting in the regions of Marrakech, Meknes and Taounate are in collection in the INRA (centers of Marrakesh and Meknes) and represent only a part of the existing diversity (Khadari et al, 2008 ;El Bakkali, 2013). In the Word, in spite of high initial varietal diversity, a recent tendency towards the establishment of the modern orchards based on the majority of the productive cultivars leads to the high erosion of this genetic material.…”

“…In the Word, in spite of high initial varietal diversity, a recent tendency towards the establishment of the modern orchards based on the majority of the productive cultivars leads to the high erosion of this genetic material. Several collections of genetic material of olive-tree were create at the national and regional level to control the genetic resources of olivetree ex-situ; to required, preserve and use them in certain programs of improvement (El Bakkali et al, 2013;Bartolini, 2008). The first attempt to preserve and characterize the most important cultivars of all the olivegrowing countries led to the creation of the World Bank of germoplasm of olive-tree in Cordoue, Spain (OWGB Cordoba).…”