Morphological and molecular characterization of Libyan olive, Olea europaea l., cultivars (42 local and 16 wild type) in comparison to 41 introduced (world) cultivars
Date
2014
Authors
Abdul Sadeg, Salem, author
Hughes, Harrison, advisor
Volk, Gayle, committee member
Brick, Mark, committee member
Holm, David, committee member
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Abstract
Olive (Olea europaea L.) consumption and production are important socially and economically in Libya. Olive cultivars that are adapted to local conditions produce olives that have high quality and quantities of oil. Many of the important olive cultivars grown in Libya were evaluated in this research. One goal of this project was to determine the plasticity of morphological traits of olive cultivars that have been grown at diverse locations within Libya. A second goal was to identify a set of traits that are independent of each other and show limited variation (stable traits) regardless of the environmental conditions. The stable traits were then used in subsequent analyses to correlate genetic and phenotypic characteristics of Libyan olives. Two different groups of olives were compared: the 45 landraces and the 45 cultivars of Olea europaea subsp europaea var. sativa. Morphological data were collected for a total of 39 morphological traits (22 quantitative and 17 qualitative), which were then combined and analyzed to determine phenotypic diversity among different locations. Differences in many of the morphological traits were observed across the cultivars. These sets of data were used to identify unique and desirable Libyan landraces morphologically. Stable phenotypic traits were used to discriminate between use of fruit (oil or dual-purpose) as well as cultivar origins (local or introduced). This research demonstrates that local Libyan cultivars (landraces) have unique characteristics that differentiate them from imported cultivars. Ten microsatellite markers were used to differentiate and evaluate the relationships among a total of 91 olive genotypes (39 landraces, 36 introduced cultivars and 16 wild types) collected in Libya. A total of 109 alleles were identified using 10 loci, with the number of alleles per locus ranging from 4 to 20. Three loci (UDO43, DCA16 and GAPU101) had the most alleles with 20, 18 and 16, respectively. The wild types and introduced cultivars had greater numbers of alleles than the local cultivars. Six cases of duplicated genotypes, two cases of synonymy, and thirteen homonyms that were genetically distinct were observed in the Libyan collection. UPGMA clustering classified the accessions into two main distinct groups. The first group consisted of landraces and the second group included introduced cultivars and wild type accessions. Admixture analysis also distinguished between landraces and wild genotypes. In general, molecular data enables one to separate the Libyan olive accessions based on their orgin but not on their fruit use.
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Subject
olive tree
morphological traits
SSR
microsatellite markers
molecular traits