Revisiting tandem duplication in plant genomes: Technical challenges and pangenome solutions.
Lim SD, Cushman JC, Yim WC
Pangenomics
The genes that let your tomatoes, wheat, and potatoes fight off blights and rusts often come in stacked duplicate sets — and scientists have been miscounting them for years, which means crop breeders may have been working from a blurry map when selecting disease-resistant varieties.
Plants keep many of their most important genes — especially the ones that fight disease — in clusters of nearly identical copies sitting right next to each other. Standard DNA-reading technology has been smooshing these clusters into a single smeared entry, like photocopying a stack of papers into one illegible page. A newer approach using longer DNA reads rebuilds those stacks accurately, finally letting scientists count and study each copy individually.
Key Findings
Short-read sequencing routinely collapses multi-gene tandem arrays into a single consensus sequence, causing systematic undercounting of disease-resistance and specialized metabolism genes
Annotation pipelines compound sequencing errors by either fusing distinct array members into one oversized gene model or dropping array members entirely, even when the underlying assembly preserved them
Graph pangenomes built from long-read, haplotype-resolved assemblies restore individual array members with distinct coordinates, enabling accurate copy-number variant genotyping and per-gene expression analysis
chevron_right Technical Summary
Standard genome sequencing tools have been systematically misreading the gene-duplication clusters that give plants their disease resistance, collapsing multiple distinct genes into one blurry copy. New long-read pangenome technology can finally reconstruct these regions accurately, revealing hidden genetic variation that matters for crop breeding.
Abstract Preview
Tandem arrays, genomic loci comprising adjacent paralogs that share high sequence identity, concentrate in plant genome regions shaped by strong adaptive pressure, from nucleotide-binding leucine-r...
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