Screening of oil palm natural populations using RAPD and RFLP molecular markers

The extent of genetic variability between and within the Elaeis guineensis Jacq. natural populations was estimated using RAPD and RFLP molecular markers. Oil palm germplasm materials collected from Nigeria, Cameroon, Zaire, Tanzania, Madagascar, Angola, Senegal, Sierra Leone, Gambia, Guinea and Ghana were screened. An advanced breeding population, Deli dura was included as a standard.A total of 176 Elaeis guineensis, 47 E.oleifera and one Deli dura population were screened using RAPD markers. Twenty random 10-mer oligonucleotide primers of arbitmy sequence were used for the study. The RAPD bands were scored (1) for the presence or (0) for the absence ofa band. A total of2285 DNA fragments were scored. The 20 primers yielded 11.4% monomorphic and 88.6% polymorphic bands. Zaire, Nigeria, Ghana and Cameroon had>90% polymorphic bands and the control Deli dura population had only 75% polymorphic bands. The Gambia collection had the lowest % of polymorphic bands because of their small restricted population. The average level of genetic diversity within populations (Hpop) was 53% and between populations was 47%. Cluster analysis showed that the collections from Nigeria, Angola, Cameroon, Tanzania and Madagascar were grouped together. The rest of the collections were grouped into asecond cluster. The Deli dura was closely linked to the Nigerian germplasm.The E.oleifera populations had more monomorphic RAPD bands compared to the E.guineensis populations, implying a greater uniformity of the E. oleifera populations. Cluster analysis show that Colombia, Costa Rica and Panama populations were distinctly different from other E.oleifera populations. E. guineensis populations andE. oleifera populations clustered into two distinct groups.For RFLP, oil palm genomic DNA was digested with five restriction enzymes and hybridized with four oil palm eDNA probes. Among the collections, Nigerian populations exhibited the highest value for all genetic variability parameters (the mean number of alleles per locus, A = 1.8; the percentage of polymorphic loci, P=63.8% and the mean expected heterozygosity, He=0.227) with the greatest number of rare alleles suggesting that Nigeria may be the likely center of diversity for oil palm. Compared to the natural populations, Deli dura has retained a substantial amount of polymorphism (P=51.7%),. The dendrogram constructed based on the genetic distance between the collections revealed two clusters whereas three countries showed single region clusters.