Role of chromosome ends in meiotic stability, recombination and wheat evolution in the context of breeding

TL;DR

This study explores how telomeres and subtelomeres in wheat influence meiosis and evolution, revealing their role as dynamic genomic barcodes for chromosome pairing and genetic diversity.

Contribution

The study identifies subtelomeric regions as hotspots for instability and genetic improvement, revealing their role in meiotic pairing and wheat evolution.

Findings

Telomeric regions show significant variability and structural complexity, influenced by genetic background and chromosomal context.

Subtelomeres act as hotspots for instability and chromatin remodelling, with uneven distribution of G-quadruplex structures.

Subtelomeric regions are key for genetic improvement, containing rapidly evolving sequences and transposable elements affecting meiotic pairing.

Abstract

Wheat is one of the most important crops worldwide, and understanding its genome organisation is crucial for geneticists and breeders. In this study, we examined the dynamic roles of telomeric and subtelomeric regions in wheat, focusing on their influence on homologous chromosome pairing during meiosis, the process that produces gametes. We analysed various Triticum species and modern cultivars, uncovering a complex “barcode” at chromosome ends that rules homologous recognition. Phylogenetic analysis of the ZIP4-5B gene highlighted the evolutionary relationships among wheat species, emphasising the contribution of wild relatives to genetic diversity, especially in terminal chromosomal regions. Our findings suggest that telomeric regions, although traditionally seen as conserved, display significant variability and structural complexity influenced by genetic background and chromosomal context. We observed a strong link between telomere position and variant accumulation, with subtelomeric regions acting as hot spots for instability and chromatin remodelling. G-quadruplex (G4) structures were found to be distributed unevenly, with their density affected by telomere distance and genomic context. Subtelomeric regions were identified as key sites for genetic improvement, harbouring rapidly evolving sequences and transposable elements that may impact meiotic pairing accuracy. Our results indicate that telomeres and subtelomeres serve as dynamic genomic centres, encoding chromosomal identity and regulating homologous pairing through a balance of sequence diversity and structural motifs. This research enhances our understanding of wheat genome stability and provides insights for breeding strategies aimed at increasing genetic diversity.

The online version contains supplementary material available at 10.1186/s12870-025-08020-5.

Telomeric and subtelomeric regions in wheat play a dynamic and critical role in meiotic chromosome pairing by acting as genomic “barcodes” that guide homologous recognition. These regions, once considered stable, show high variability and structural complexity influenced by genetic and evolutionary factors, especially through contributions from wild wheat relatives. The findings highlight subtelomeres as hotspots for genetic improvement and genome evolution, offering valuable insights for enhancing wheat breeding and genetic diversity.

The online version contains supplementary material available at 10.1186/s12870-025-08020-5.

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