Identifying Vitamin E Biosynthesis Genes in Elaeis guineensis by Genome-Wide Association Study

Elaeis guineensis is a tropical
oil crop and has the highest oil yield per unit area. Palm oil has
high palmitic acid content and is also rich in vitamins, including
vitamin E. We conducted genome-wide association studies in a diversity
panel of 161 E. guineensis accessions
to identify single-nucleotide polymorphisms (SNPs) linked with vitamin
E and validated candidate genes in these marker-associated intervals.
Based on the SNPs reported in our previous research, 47 SNP markers
were detected to be significantly associated with the variation of
tocopherol and tocotrienol content at a cutoff P value
of 6.3 × 10–7. A total of 656 candidate genes
in the flanking regions of the 47 SNPs were identified, followed by
pathway enrichment analysis. Of these candidate genes, EgHGGT (homogentisate geranylgeranyl transferase) involved in the biosynthesis
of tocotrienols had a higher expression level in the mesocarp compared
to other tissues. Expression of the EgHGGT gene was
positively correlated with the variation in α-tocotrienol content.
Induced overexpression of the gene in Arabidopsis caused a significant increase
in vitamin E content and production of α-tocotrienols compared
to wild Arabidopsis.