Genomic and transcriptomic analyses provide insights into valuable fatty acid biosynthesis and environmental adaptation of yellowhorn

Abstract

Yellowhorn (Xanthoceras sorbifolium) is an oil-bearing tree species growing naturally in poor soil. The kernel of yellowhorn contains valuable fatty acids like nervonic acid. However, the genetic basis underlying the biosynthesis of valued fatty acids and adaptation to harsh environments is mainly unexplored in yellowhorn. Here, we presented a haplotype-resolved chromosome-scale genome assembly of yellowhorn with the size of 490.44 Mb containing scaffold N50 of 34.27 Mb. Comparative genomics, in combination with transcriptome profiling analyses, showed that expansion of gene families like long-chain acyl-CoA synthetase and ankyrins contribute to yellowhorn fatty acid biosynthesis and defense against abiotic stresses, respectively. By integrating genomic and transcriptomic data of yellowhorn, we found that the transcription of 3-ketoacyl-CoA synthase gene XS04G00959 was consistent with the accumulation of nervonic and erucic acid biosynthesis, suggesting its critical regulatory roles in their biosynthesis. Collectively, these results enhance our understanding of the genetic basis underlying the biosynthesis of valuable fatty acids and adaptation to harsh environments in yellowhorn and provide foundations for its genetic improvement.

Genome-wide association analysis identifies a candidate gene controlling seed size and yield in Xanthoceras sorbifolium Bunge

“…Four yellow horn reference genomes have been published: ZS4 [ 39 ], JGXP [ 40 ], WF18v1 [ 41 ], and WF18v2 [ 42 ]. Given the closer relationship between the sequenced samples and ZS4 yellow horn, we selected the ZS4 genome as our reference genome.…”

Agronomic, physiological and transcriptional characteristics provide insights into fatty acid biosynthesis in yellowhorn (Xanthoceras sorbifolium Bunge) during fruit ripening

“…After FFAs of different lengths are converted into acyl-CoA, they are transported to the cytoplasm and endoplasmic reticulum. Acyl CoA and 3-phosphatidylglycerol can then be converted into triacylglycerol (TAG) by enzymes including 3-ketoacylCoA synthase (KCS), 3-ketoacyl-CoA reductase (KCR), 3-hydroxacyl-CoA dehydratase (HCD), and trans-2,3-enoyl-CoA reductase (ECR), resulting in the production of the C18, C20, C22, and C24 fatty acid series ( Liang et al, 2022 ).…”

“…Subsequently, Liu et al (2021) assembled the Jinguanxiapei cultivar genome, which had a size of 470 Mb, and analyzed the transcriptomes from different tissues, identifying candidate genes involved in very-long-chain fatty acid biosynthesis and their expression profiles. Liang et al (2022) also upgraded the genome assembly for WF18, producing an updated version with a size of 490.44 Mb. These advancements lay a foundation for functional genomics research on X .…”

High-quality genome assembly and comparative genomic profiling of yellowhorn (Xanthoceras sorbifolia) revealed environmental adaptation footprints and seed oil contents variations

“…Furthermore, yellowhorn is easy to reproduce, sowing, root cutting, and grafting and is now considered a promising afforestation species for many arid areas. This oil-rich tree produces capsular fruits from hermaphrodites, with about 60% of its seed kernel containing edible seed oil for the human diet and around 4% nervonic acid essential for nerve and brain development with high medicinal and ornamental value ( Liang et al., 2019 ; Liang et al., 2022 ). However, yellowhorn also contains moderate erucic acid (about 9% of the total fatty acid) that can damage the heart at high doses ( Liu et al., 2021b ).…”

“…The rapid development of sequencing technologies has facilitated the development of yellowhorn genomes, with two good-quality yellowhorn genome assemblies being published recently ( Liang et al., 2019 ; Liang et al., 2022 ). These published yellowhorn genomes were sampled and collected from a valley terrain environment with mountains and rivers in Shandong Province.…”