Genetic flow among olive populations within the Mediterranean basin

Abstract

BackgroundThe olive tree is a typical crop of the Mediterranean basin where it shows a wide diversity, accounting for more than 2,600 cultivars. The ability to discriminate olive cultivars and determine their genetic variability is pivotal for an optimal exploitation of olive genetic resources.MethodsWe investigated the genetic diversity within 128 olive accessions belonging to four countries in the Mediterranean Basin (Italy, Algeria, Syria, and Malta), with the purpose of better understanding the origin and spread of the olive genotypes across Mediterranean Basin countries. Eleven highly polymorphic simple sequence repeat (SSR) markers were used and proved to be very informative, producing a total of 179 alleles.ResultsCluster analysis distinguished three main groups according to their geographical origin, with the current sample of Maltese accessions included in the Italian group. Phylogenetic analysis further differentiated Italian and Maltese olive accessions, clarifying the intermediate position of Maltese accessions along the x/y-axes of principal coordinate analysis (PCoA). Model-based and neighbor clustering, PCoA, and migration analysis suggested the existence of two different gene pools (Algerian and Syrian) and that the genetic exchange occurred between the Syrian, Italian and Maltese populations.DiscussionThe close relationship between Syrian and Italian and Maltese olives was consistent with the historical domestication and migration of olive tree from the North Levant to eastern Mediterranean basin. This study lays the foundations for a better understanding of olive genetic diversity in the Mediterranean basin and represents a step toward an optimal conservation and exploitation of olive genetic resources.

The newly developed genomic-SSR markers uncover the genetic characteristics and relationships of olive accessions

“…Moreover, globalization has intensified the movement of olive cultivars between countries, thereby strengthening the gene flow (Trujillo et al, 2013). Several traditional olive cultivars such as ''Frantoio'', ''Pendoline'', ''Coratina'', ''Ottobratica'' and ''Ascolana Tenera'' clustered into a same subgroup, exhibiting a close genetic relationship consistent with previous studies (Biton et al, 2015;Mousavi et al, 2017;Di Rienzo et al, 2018;Cultrera et al, 2019). Additionally, the genetic relationship of 11 accessions was previously reported based on the published SSRs, including ''Frantoio '', ''Coratina'', ''Leccino'', ''Pendoline'', ''Ascolana Tenera'', ''Koroneiki'', ''Kalamon'', ''Grossanne'', ''EzhiNo.8'', ''Chenggu32'', and ''Chenggu53'' (Qin et al, 2016).…”

Assessment of Genetic Diversity of the “Acquaviva Red Onion” (Allium cepa L.) Apulian Landrace

“…The overall F is value calculated in onion populations considered in this study (0.054) was lower than that the one previously reported by [45] (0.22) and almost identical to the one found by [31] (0.08) and [48] (0.00) who assessed genetic diversity in onion landraces from northwest Spain and Niger, respectively. Noteworthy levels of heterozygosity in ARO populations reinforce the notion that Apulia represents a diversity center for many horticultural species [32,42,[49][50][51].…”

Recovery, Assessment, and Molecular Characterization of Minor Olive Genotypes in Tunisia

“…A set of 12 microsatellite markers, previously proven to be highly performant for genetic olive characterization, were used (Table S7) [54][55][56]. PCR reactions were conducted in a final volume of 12.5 µL, according to di Rienzo et al [6]. In brief, 1.25 µL of 10X Dream Taq Buffer, 0.6 µL of 2M dNTP, 1.25 µL of a mix of primers (2.5 µM), 0.2 µL of Dream Taq, and 7.7 µL H 2 O were added in each well containing 50 ng of DNA.…”

“…It is considered a symbol of the Mediterranean cultural heritage, an emblem of longevity and unity since the time of Roman domination, when it constituted a political and religious myth [3]. In Tunisia, its history dates back to the Phoenicians and Romans, whose commercial exchanges contributed to developing the gene fluxes and promoted the introgression of alleles from oleaster and other O. europaea subspecies, allowing the olive germplasm to be continuously diversified [4][5][6].…”

“…The aim of the project was to efficiently recover new germplasm in the territory, and to genetically characterize it. Simple sequence repeat (SSR) markers were chosen, as they are still considered highly reliable in the identification of varieties of different crops [19][20][21][22], including olive [23][24][25][26], population genetics [4][5][6], and product traceability [27][28][29][30].…”