Jiantao Guan, Xiangsheng Li, H. Miao, Xuemei Yan, Xiaoping Liu, et al. (2026).
Pangenome-resolved structural variation drives adaptation and trait evolution in cucumber.
Nature Genetics. 10.1038/s41588-026-02682-z
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Pangenome-resolved structural variation in cucumber
Why this matters: A 125-accession chromosome-scale pangenome of cucumber reveals that structural variants — not just SNPs — are major drivers of local adaptation, disease resistance, and fruit-shape diversification, providing a direct toolkit for precision breeding.
Background
Cucumber (Cucumis sativus L.) is both a globally important vegetable and a model for sex determination, fruit development, and vascular biology. Single-reference genomes underrepresent the crop’s worldwide diversity and miss the structural variation (SV) that often underlies agronomic traits. The authors asked: how much of cucumber’s trait and adaptive diversity is encoded in SVs invisible to reference-based analyses?
Methods
- High-quality genome assemblies were generated for 125 cultivated and wild accessions spanning the crop’s global range.
- Syntenic gene family analysis was used to define orthologous groups and haplotype structure across accessions.
- SVs were catalogued pangenome-wide and their regulatory effects on gene expression quantified.
- SVs were then integrated into GWAS across 38 agronomic traits to map QTLs beyond what SNP-only analyses can detect.
Key findings
- 37,897 gene families were characterized, with haplotype diversity structured by geographic expansion.
- Copy-number variation is linked to local adaptation: a tandem duplication of CsFT promotes early flowering at higher latitudes.
- Reduced reference bias enabled annotation of resistance loci, including discovery of CsCcu, an NLR-type R gene conferring scab resistance.
- 135,597 SVs were catalogued; ~30% are associated with trait diversification among geographic groups.
- SV-inclusive GWAS identified 172 QTLs across 38 traits, including a rare LTR insertion regulating fruit length via CsSPL1.
Open questions
The abstract does not detail functional validation beyond the highlighted loci (CsFT, CsCcu, CsSPL1), leaving open how many of the 172 QTLs and ~30% trait-associated SVs are causal versus linked, and how transferable these variants are across breeding backgrounds.
Original abstract
Cucumber (Cucumis sativus L.) is a global vegetable crop and powerful model for sex determination, fruit development and vascular biology. We present high-quality genome assemblies for 125 cultivated and wild accessions, capturing worldwide genetic diversity. Syntenic gene family analysis characterized 37,897 gene families and revealed haplotype diversity shaped by geographic expansion. Comparative analyses uncovered copy-number variations linked to local adaptation, including a CsFT tandem duplication promoting early flowering at higher latitudes. This resource reduces reference bias, enabling the annotation of resistance loci and the discovery of CsCcu, a nucleotide-binding leucine-rich repeat-type R gene conferring scab resistance. We cataloged 135,597 structural variations and quantified their regulatory effects, with ~30% driving trait diversification among geographic groups. Integrating structural variations into genome-wide association studies identified 172 quantitative trait loci for 38 agronomic traits, including a rare long terminal repeat insertion regulating fruit length via CsSPL1. Our findings provide a genomic toolkit for cucumber evolution research and precision breeding. Pangenome analyses of chromosome-scale genome assemblies for 125 diverse cucumber accessions highlight structural variation shaped by selection for geographical adaptation, fruit-length diversification and disease resistance.
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