Genome sequencing of the high oil crop sesame provides insight into oil biosynthesis

Abstract

BackgroundSesame, Sesamum indicum L., is considered the queen of oilseeds for its high oil content and quality, and is grown widely in tropical and subtropical areas as an important source of oil and protein. However, the molecular biology of sesame is largely unexplored.ResultsHere, we report a high-quality genome sequence of sesame assembled de novo with a contig N50 of 52.2 kb and a scaffold N50 of 2.1 Mb, containing an estimated 27,148 genes. The results reveal novel, independent whole genome duplication and the absence of the Toll/interleukin-1 receptor domain in resistance genes. Candidate genes and oil biosynthetic pathways contributing to high oil content were discovered by comparative genomic and transcriptomic analyses. These revealed the expansion of type 1 lipid transfer genes by tandem duplication, the contraction of lipid degradation genes, and the differential expression of essential genes in the triacylglycerol biosynthesis pathway, particularly in the early stage of seed development. Resequencing data in 29 sesame accessions from 12 countries suggested that the high genetic diversity of lipid-related genes might be associated with the wide variation in oil content. Additionally, the results shed light on the pivotal stage of seed development, oil accumulation and potential key genes for sesamin production, an important pharmacological constituent of sesame.ConclusionsAs an important species from the order Lamiales and a high oil crop, the sesame genome will facilitate future research on the evolution of eudicots, as well as the study of lipid biosynthesis and potential genetic improvement of sesame.

Large-Scale Analyses of Angiosperm Nucleotide-Binding Site-Leucine-Rich Repeat Genes Reveal Three Anciently Diverged Classes with Distinct Evolutionary Patterns

“…This finding indicates that CNL genes adopted a gradual expansion strategy in the early stage of angiosperm evolution (from ;225 MYA as angiosperms diverged to around 100 MYA as asterids, rosids, and monocots diverged; Fig. 1; D 'Hont et al, 2012;Wang et al, 2014;Zeng et al, 2014). Intensive expansion of CNL genes seems to have occurred in the familial ancestors of Solanaceae and Poaceae, reaching hundreds of copies.…”

“…Because the divergence of these angiosperm families occurred in the Paleogene and the divergence of their higher level taxonomies all occurred in the Cretaceous ( Fig. 1; Lavin et al, 2005;Stefanovic et al, 2009;D'Hont et al, 2012;Zhang et al, 2012;Peng et al, 2013;Yang et al, 2013;Kim et al, 2014;Wang et al, 2014;Zeng et al, 2014), the observed intensive expansion of NBS genes in angiosperms more likely coincided with the CretaceousPaleogene (K-P) boundary (;66 MYA). This finding suggests that different lineages of angiosperms either underwent a process to reinforce resistance or experienced increased selective pressure from environmental pathogens during this period.…”

“…The Solanaceae nTNL genes formed 55 monophyletic lineages with nTNL genes from S. indicum (two RNL lineages The phylogenetic relationship was constructed according to the APG III system (Bremer et al, 2009). The divergence times at different nodes of angiosperms were combined from previous studies (Lavin et al, 2005;Stefanovic et al, 2009;D'Hont et al, 2012;Zhang et al, 2012;Peng et al, 2013;Yang et al, 2013;Kim et al, 2014;Wang et al, 2014;Zeng et al, 2014). The total number of NBS genes and their classification in each species are shown.…”

“…Files of Amborella trichopoda, Capsicum annuum, Sesamum indicum, Phyllostachys heterocycla, and Musa acuminata were downloaded from the Pepper Genome Database (http://peppersequence. genomics.cn/page/species/index.jsp; Qin et al, 2014), Sinbase (http://ocrigenomics.org/Sinbase/manual.htm; Wang et al, 2014), BambooGDB (http:// www.bamboogdb.org/page/download.jsp; Peng et al, 2013), Banana Genome Hub (http://banana-genome.cirad.fr; D 'Hont et al, 2012), and the Amborella genome database (http://www.amborella.org; Amborella-Genome-Project, 2013), respectively.…”

Genome of wild olive and the evolution of oil biosynthesis

“…Within the Lamiales, multiple WGD independent from the paleopolyploidy in the Solanales have been described: two or three in the lineage leading to U. gibba (one of which could be shared with M. guttatus) (18), and one in the lineage leading to S. indicum (estimated age similar to tomato) (19). This latter one and the oldest WGD in U. gibba could denote the same event, possibly even shared with the older WGD in the oleaster and ash lineage, or both could be independent ones, partly depending on their phylogenetic relationship (SI Appendix, section 3.2).…”