Comparative transcriptome profiling and molecular marker development for oil palm fruit color

Oil palm harvesting is normally determined by fruit exocarp color. To detect expressed sequence tag (EST)-simple sequence repeat (SSR) markers in oil palm hybrid populations, de novo transcriptomic profiling of Nigeria black and Suratthani 1 (Deli × Calabar) plants was performed. More than 46 million high-quality clean reads with a mean length of 1117 bp were generated. Functional annotation and gene ontology (GO) enrichment analysis of differentially expressed genes (DEGs) revealed that the genes were involved in fruit color development and pigment synthesis. Comparison of immature/mature DEGs indicated that nigrescent fruit color was driven by the anthocyanin biosynthesis pathway (ABP); however, the carotenoid biosynthesis pathway (CBP) was involved in the color development of both fruit types. The transcripts of both unique and different genes involved in the ABP and CBP in higher plants were highlighted for further study, especially 3GT, downstream genes in the ABP, and DEARF27 in the CBP. Additionally, SSR primer motifs, namely, 9949, discovered from the DEGs upregulated in the virescent type that encode vacuolar iron transporter (VIT), could separate the nigrescence and virescence traits of Nigeria hybrids. This novel primer has potential to be used as a molecular for further selection in breeding programs especially involving the specific genetic backgrounds described in this study.