Genetic diversity of dacryodes edulis provenances from cameroon used in controlled breeding trials
Otieno, Gordon Felix O.
MetadataShow full item record
Dacryodes edulis (G.Don) HJ.Lam, otherwise called African plum, belongs to the Burseraceae, a tropical tree family. The edible and nutritious fruit is the economic part that gives the tree its true economic value and hence explains why it is both domesticated and cultivated in commercial orchards. Three D. edulis provenances are currently being used in controlled breeding trials at World Agro forestry Centre- Cameroon. However, limited knowledge of the genetic diversity of these provenances has been a drawback to the breeding program. Therefore, this study assessed the genetic diversity of the three D. edulis provenances based on Simple Sequence Repeats (SSRs) marker technique with an aim of providing crucial background information on genetic diversity for the efficient management and utilization of the collections in the breeding programme. Genomic DNA isolated from individual D. edulis samples were primed with six SSR primers (CB09, LD06, CGll, LB12 CE09 and CC01), amplified through PCR and the amplification products resolved using the ABI 3730 DNA analyzer. Alleles were called using the Gene Mapper software (version 3.7). The polymorphism information content (PlC), gene diversity and heterozygosity estimates were computed using PowerMarker software Version 3.25. GenAIEx software version 6.5 was employed to estimate gene flow levels, reveal partitioning of variation across the populations and display the genetic relationships among the populations. DARwin software Version 5.0 was used to construct a dendogram that also displayed the genetic relationships among the populations. All the six primer pairs used in this study were polymorphic. Gene diversity values calculated for all analyzed loci ranged from 0.2763 to 0.8846 for the loci CG 11 and CE09, respectively, with a mean of 0.5851. Heterozygosity values ranged from 0.0220 and 0.5385 for the loci CG 11and LD06, respectively, with an average of 0.3132. A significant low level of genetic differentiation (F ST = 0.018, p=O.O10) was detected among the populations. AMOV A analysis indicated that only 2% of genetic variation existed among populations. The neighbor joining tree and PCoA analysis could not reveal a clear separation between populations. Consequently, this study established there is a high common level of gene flow that helps in maintaining low genetic' differentiation and close genetic relationships among the populations studied. Thus, introgression of new alleles may be required to broaden the genetic base of the D. edulis provenances. This study also highlights the need of isolation and characterization of more DNA markers in D. edulis and their uses in advanced studies such as gene discovery, trait linked marker assisted selection and gene mapping.