Genome-Wide Association Mapping of Oil Content and Seed Related Traits in Shea Tree (Vitellaria paradoxa subsp. nilotica) Population

Shea tree (Vitellaria paradoxa) is an important fruit tree crop because of its oil used for cooking and industrial manufacture of cosmetics. Despite its many benefits, quantitative trait loci linked to the economic traits have not yet been studied. In this study, we performed association mapping on a panel of 374 shea tree accessions using 7,530 single-nucleotide polymorphisms (SNPs) markers for oil yield and seed related traits. Twenty three markers that were significantly (–log10 (p) = 4.87) associated to kernel oil content, kernel length; width and weight were identified. The kernel dry matter oil content and kernel width had the most significant Marker Trait Association (MTA) on chromosomes 1 and 8 respectively. Sixteen candidate genes that condition early induction of flower buds and somatic embryos, seed growth and development, substrate binding, transport, lipid biosynthesis, metabolic processes during seed germination and disease resistance and abiotic stress adaptation were identified. The presence of these genes suggest their role in promoting shea bioactive functions that condition high oil synthesis. This study provides insights into the important marker-linked seed traits with genes controlling them, useful for molecular breeding for improving oil yield in the species.