Tung Tree (Vernicia Fordii) Genome Provides A Resource for Understanding Genome Evolution and Improved Oil Production

Abstract

Tung tree (Vernicia fordii) is an economically important woody oil plant that produces tung oil rich in eleostearic acid. Here, we report a high-quality chromosome-scale genome sequence of tung tree. The genome sequence was assembled by combining Illumina short reads, Pacific Biosciences single-molecule real-time long reads, and Hi-C sequencing data. The size of tung tree genome is 1.12 Gb, with 28,422 predicted genes and over 73% repeat sequences. The V. fordii underwent an ancient genome triplication event shared by core eudicots but no further whole-genome duplication in the subsequent ca. 34.55 million years of evolutionary history of the tung tree lineage. Insertion time analysis revealed that repeat-driven genome expansion might have arisen as a result of long-standing long terminal repeat retrotransposon bursts and lack of efficient DNA deletion mechanisms. The genome harbors 88 resistance genes encoding nucleotide-binding sites; 17 of these genes may be involved in early-infection stage of Fusarium wilt resistance. Further, 651 oil-related genes were identified, 88 of which are predicted to be directly involved in tung oil biosynthesis. Relatively few phosphoenolpyruvate carboxykinase genes, and synergistic effects between transcription factors and oil biosynthesis-related genes might contribute to the high oil content of tung seed. The tung tree genome constitutes a valuable resource for understanding genome evolution, as well as for molecular breeding and genetic improvements for oil production.

Genomic insights into the origin, domestication and genetic basis of agronomic traits of castor bean

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Transcriptome analyses reveals the dynamic nature of oil accumulation during seed development of Plukenetia volubilis L.

“…For example, during the biosynthesis of tung oil in seeds of the tung tree (Venicia fordii), the contents of LA and ALA are higher in young seed and gradually decrease as seed matures. Correspondingly, DGAT2 and PDAT are highly expressed in the earlier stages of seed development in this latter species 45 . In this current study, the transcripts of DGAT1and PDAT1 (Unigene0020593 and Unigene0016056, respectively) were upregulated in mature seed (SI-5) (Fig.…”

The ancient wave of polyploidization events in flowering plants and their facilitated adaptation to environmental stress

“…The grape species (Vitis vinifera) only experienced this ancient whole-genome triplication event without any additional wholegenome duplications. The γ whole-genome triplication was later confirmed to have occurred in different species, such as papaya, coffee, cocoa, peach, tung tree and hardy rubber tree (Argout et al, 2011;Denoeud et al, 2014;International Peach Genome et al, 2013;Jaillon et al, 2007;Tang et al, 2008;Wuyun et al, 2018;Zhang, Liu, et al, 2019). A broader sampling and analyses using orthologs suggested that the whole-genome triplication occurred before the divergence of the rosids and asterids and after the separation of F I G U R E 1 Species richness and polyploidy events in the flowering plants.…”