Genetic diversity of natural oil palm (Elaeis guineensis Jacq.) populations using microsatellite markers.
A total of 494 palms from 49 populations representing 10 African countries and few breeding materials were genotyped using 16 microsatellite loci representing the haploid genome of oil palm. The 16 microsatellite loci were polymorphic (0.99 criterion) across all populations with the exception of populations from Madagascar, where 14 of the 16 were invariant. A total of 209 alleles were detected across the 49 populations. The common allele was not always the same among populations of the same country. Rare alleles (p 0.05) were mostly found in populations from Senegal, Sierra Leone, Guinea and Nigeria and surprisingly in Deli MPOB (Malaysian Palm Oil Board) breeding material. Mean number of alleles per locus (A) ranged from 1.1 in populations from Madagascar to 6.7 in population 40 from Nigeria (mean 5.0 1.7). The effective number of alleles per locus (Ae) varied between 1.1 in populations from Madagascar and 4.7 in population 40 from Nigeria (mean 3.3 1.3). Mean expected heterozygosity (He) was high (0.644 0.163) ranging from 0.033 (population 3 from Madagascar) to 0.803 (population 40 from Nigeria). The presence of rare alleles and the high values of genetic diversity parameters in populations from Nigeria suggested this country to be the centre of diversity for oil palm. The Chi-square tests for deviation of genotypic frequencies showed that on average 46 percent of the loci deviated from the Hardy-Weinberg expectations. The fixation indices were positive ranging from 0.126 to 1 were detected in most populations indicating an excess of homozygotes. These results may most probably due to small population size. The overall degree of genetic differentiation among populations was high (FST0.253 and RST 0.282).Estimations of genetic differentiation between the five geographical zones showed that 75.0 percent (RST 0.250) of the variation observed lies within zones. The lowest RST value (on average 0.029) was between Central Africa (Cameroon, Zaire, Angola) and East Africa (Tanzania) zones. The total gene flow (Nm) across natural oil palm populations was low (Nm 0.739, F-statistics and Nm 0.638, R-statistics) indicating that low migration had taken place between populations in accordance with the high FST and RST between populations. Maximum gene flow (Nm 8.268) was found between Central Africa and East Africa geographical zones. The average genetic distance among oil palm populations was 0.684. Total divergence also existed between many populations from the Extreme West Africa (Senegal, Guinea, and SierraLeone) and populations from West, Central and East Africa. The UPGMA cluster analysis showed three main clusters. Populations from Madagascar formed one cluster meanwhile populations from Senegal, Guinea and Sierra Leone formed the second cluster. Populations from Ghana, Nigeria, Cameroon, Zaire, Angola, Tanzania and breeding materials formed the third cluster. Deli MPOB and Deli Dabou (sources of dura parents for two different breeding programmes) were grouped together confirming their common origin (Deli). Twenty three populations with relatively high effective number of alleles per locus (Ae 3.6) should be conserved, while twenty two showing high genetic diversity (He 0.700) can be selected for inclusion in the base populations for breeding programmes. The correlation coefficient between Ho and He and to altitude (r -0.18 and r -0.07, respectively) was not significant (p 0.05)
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| Format: | Texto biblioteca |
| Language: | ng |
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Bangi (Malaysia) : Universiti Kebangsaan Malaysia. Faculty of Science and Technology,
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| Subjects: | Palma africana, Evolución de las plantas, Anatomía vegetal, |
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