BackgroundThe commercial oil palm (Elaeis guineensis Jacq.) produces a mesocarp oil (commonly called ‘palm oil’) with approximately equal proportions of saturated and unsaturated fatty acids (FAs). An increase in unsaturated FAs content or iodine value (IV) as a measure of the degree of unsaturation would help to open up new markets for the oil. One way to manipulate the fatty acid composition (FAC) in palm oil is through introgression of favourable alleles from the American oil palm, E. oleifera, which has a more unsaturated oil.ResultsIn this study, a segregating E. oleifera x E. guineensis (OxG) hybrid population for FAC is used to identify quantitative trait loci (QTLs) linked to IV and various FAs. QTL analysis revealed 10 major and two putative QTLs for IV and six FAs, C14:0, C16:0, C16:1, C18:0, C18:1 and C18:2 distributed across six linkage groups (LGs), OT1, T2, T3, OT4, OT6 and T9. The major QTLs for IV and C16:0 on LGOT1 explained 60.0 – 69.0 % of the phenotypic trait variation and were validated in two independent BC2 populations. The genomic interval contains several key structural genes in the FA and oil biosynthesis pathways such as PATE/FATB, HIBCH, BASS2, LACS4 and DGAT1 and also a relevant transcription factor (TF), WRI1. The literature suggests that some of these genes can exhibit pleiotropic effects in the regulatory networks of these traits. Using the whole genome sequence data, markers tightly linked to the candidate genes were also developed. Clustering trait values according to the allelic forms of these candidate markers revealed significant differences in the IV and FAs of the palms in the mapping and validation crosses.ConclusionsThe candidate gene approach described and exploited here is useful to identify the potential causal genes linked to FAC and can be adopted for marker-assisted selection (MAS) in oil palm.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2607-4) contains supplementary material, which is available to authorized users.

The extent of genetic diversity among 494 oil palms from 49 populations (representing ten African countries, three breeding materials, and one semi-wild material) were assessed using 16 SSR markers. The genetic diversity was high with a total of 209 alleles detected accounting for an average of 13.

The allelic diversity within oil palm populations (45 native ones from 10 African countries, three breeding populations and one collection of semi-wild material) was determined using 16 microsatellite markers. A total of 209 alleles were detected, with a mean number of 13.1 alleles per locus. The mean effective number of alleles per locus (A e ) was 3.3^1.3. Although the Duncan's multiple range test only separated the group of populations from Madagascar from the rest on the basis of A e , the presence of unique and rare alleles and high values of A e suggest that 23 of the African populations should be conserved to secure allelic diversity. ExperimentalFrom a sample of 494 oil palms, derived from 45 native African populations (Fig. 1), two Deli and one La Mé (Côte d'Ivoire) breeding populations, and one semiwild population Bahia (Brazil), 16 microsatellite markers (Billotte et al., 2005) were used to derive genotypic descriptions. DNA was extracted from leaf material using a CTAB procedure (Doyle and Doyle, 1990). PCR amplifications were performed according to Billotte et al. (2001), and the amplicons were separated on 7% denaturing polyacrylamide gels. Profiles were visualized by silver staining. POPGENE version 1.32 software (Yeh and Boyle, 1999) was used to estimate allele frequencies and the effective number (A e ) of alleles per locus. The generalized linear model procedure in SAS software was used to perform one-way ANOVA for A e and also the Duncan's multiple range test of comparison of all the populations based on their mean values of A e . DiscussionA combination of rapid population growth, urbanization and the development of agriculture is predicted to

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The performance of 11 oil palm AVROS (Algemene Vereniging van Rubberplanters ter Oostkust van Sumatra) pisiferas was evaluated based on their 40 dura x pisifera (DxP) progenies tested on inland soils, predominantly of Serdang Series. Fresh fruit bunch (FFB) yield of each pisiferas ranged from 121.93 to 143.9 kg palm−1 yr−1 with trial mean of 131.62 kg palm−1 yr−1. Analysis of variance (ANOVA) showed low genetic variability among pisifera parents for most of the characters indicating uniformity of the pisifera population. This was anticipated as the AVROS pisiferas were derived from small population and were inbred materials. However, some of the pisiferas have shown good general combining ability (GCA) for certain important economic traits. Three pisiferas (P1 (0.174/247), P3 (0.174/498), P11 (0.182/308)) were identified of having good GCA for FFB yield while pisiferas P1 (0.174/247), P10 (0.182/348), and P11 (0.182/308) were good combiners for oil-to-bunch ratio (O/B). The narrow genetic base of these materials was the main obstacle in breeding and population improvement. However, efforts have been made to introgress this material with the vast oil palm germplasm collections of MPOB for rectifying the problem.