Identification of candidate genes responsible for morphological and yield-related traits via genome-wide association analysis (GWAS) in oil palm (Elaeis oleifera x Elaeis guineensis)

Background The genus Elaeis has two species of economic importance for the oil palm agroindustry: Elaeis oleifera (O), native to the Americas, and Elaeis guineensis (G), native to Africa. The breeding program in Colombia relies on interspecific OxG crossing populations with tolerance to pests and diseases, high oil quality, and acceptable fruit bunch production. The identification of loci associated to morphological and yield-related traits and the dissection of their genetic architecture will provide essential insights for oil palm breeding strategies. Results The genotypes of 471 oil palms, including 62 E. oleifera (O), 31 E. guineensis (G) and 378 OxG samples were analyzed in this study. A total of 3,776 single nucleotide polymorphisms (SNP) were detected across the 16 oil palm chromosomes using the genotyping-by-sequencing (GBS) technique. The genetic variation and population structure analyses grouped the samples into two clades according to the parental relatedness. A genome wide association analysis (GWAS) was conducting using the OxG hybrid population, resulting in 12 SNPs significantly associated with ten different morphological and yield-related traits. Conclusions The work presented herein provides to our knowledge the first association mapping study in an interspecific OxG hybrid population of oil palm. We provide new insights on candidate genes involved in tissue development and plant architecture associated to traits such as: rachis length, trunk diameter, bunch number, and bunch weight. The genes identified in our analysis are putative candidates for future targeted functional analysis. They are valuable resources for the development of marker-assisted selection in oil palm breeding. Keywords: Association mapping, Elaeis guineensis, Elaeis oleifera, genotyping-by-sequencing, plant architecture, yield.