Genetic Diversity, Oil Content and Fatty Acid Composition of Vernonia [Vernonia Galamensis (Cass.) Less] Germplasm In Ethiopia
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Date
2020-07-07
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Addis Ababa University
Abstract
Vernonia (Vernonia galamensis) is a potential novel industrial crop due to high sources of natural epoxidized oil, which can be used for the manufacturing of polyvinyl chloride, petrochemicals, cosmetic and pharmaceutical products. In spite of its high potential as an industrial plant, however, the plant is underutilized. No much attention has been given to research and conservation of this plant. The species is also under the threat of continued genetic erosion. This study was therefore initiated to assess the genetic diversity of V. galamensis accessions through morphological characterization and SSR molecular markers. In addition, oil content and fatty acid composition of the plant were investigated.
For agro-morphological trait study, 80 accessions of V. galamensis were grown in alpha-lattice design with two replications at Melka Werer and Wondo Genet Agricultural Research Centers. Data on a total of 13 quantitative traits were collected and analyzed using graph pad prism V-7, SAS V 9.0 and MINITAB V17.1 software. For molecular analysis, 20 SSR markers were used to analyses genetic diversity of a total of 10 populations using GenAlex software. Seed oil content was determined using Soxhlet method, and fatty acid composition was using Gas Chromatography Mass Spectroscopy. Data analysis for seed oil content and fatty acid composition were conducted using SAS V 9.0 and Minitab V17.1 software (Minitab, 2013).
Agro-morphological quantitative characters have highly significant variation (p <0.05) for most of the quantitative traits among accessions except for days to emergence. The mean performance of seed yield per hectare ranged from 348.9 to 573.7 Kg ha-1.The highest genotypic coefficient of variation (GCV) was observed for seed weight per plot (95.44), while the highest phenotypic coefficient of variation (PCV) was observed for branch length xv
(99.48). Seed yield per hectare showed significant and positive correlations with days to 50% heading (r = 0.50). High heritability coupled with high genetic advance as percentage of the mean was recorded for number of heads per plant and seed weight per plot. Number of heads per plant showed the highest positive direct effect (0.72) and genotypic correlation (r= 0.86) with seed yield per hectare. The result of principal component analysis indicated that those exhibited more than one eigenvalue were about 71.0% of variability.
The marker detected a total of 79 alleles/bands. The observed heterozygosity (Ho) values were quite low which ranged between 0.05 and 0.36, whereas the expected heterozygosity (He) ranged from 0.23 to 0.64. Two allelic patterns, East Showa and East Hararghe populations had the highest expected heterozygosity. The markers also showed the highest polymorphic information content that ranged between 0.50 (Vg-005) and 0.96 (Vg-002) with an average of 0.76. Molecular analysis of variance (AMOVA) showed 11% of variation among populations and 67% of the variation within populations. Dendrogram clusters, principal coordinate and population structure analyses showed that accessions collected from the same region of origin did not often grouped entirely together within a given major groups, suggesting that strong gene flow between populations.
The seed oil content and fatty acids composition analysis revealed significant variations, and the seed oil content ranged from 31.18% to 36.67% with an average of 33.24%. The fatty acids composition profiles also showed vernolic acid is the predominant fatty acid that ranged from 71.45% to 78.43% with an average of 73.72%.
Overall, the plant showed high genetic, phenotypic, and oil content variations, and will be used as the potential accessions (as potential parent sources) in V. galamensis improvement and genetic conservation endeavor in Ethiopia.
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Keywords
Vernonia, Epoxy Oil, Vernolic Acid, Dendrogram, Heritability, Heterozygosity, Principal Component