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<p>The unambiguous identification of individual chromosomes is fundamental to studying genome organisation and evolution. Sheepgrass (<i>Leymus chinensis</i> (Trin.) Tzvel), a perennial tetraploid grass closely related to wheat, is a valuable genetic resource for crop improvement. Here, we employed low-coverage sequencing and bioinformatics analysis to isolate and characterise a set of species-characteristic repetitive sequences in sheepgrass, including CL6, CL95, CL121, CL151, CL162, CL163, CL239, 5&#xa0;S ribosomal DNA (rDNA), and 26&#xa0;S rDNA. A multicolour fluorescence in situ hybridisation (FISH) assay using a probe cocktail targeting CL6, CL121, CL162, 5&#xa0;S rDNA, and 26&#xa0;S rDNA successfully distinguished all 28 sheepgrass chromosomes. On the basis of the close evolutionary relationship between wheat and sheepgrass, single-copy genes with known linkage map locations for wheat were applied to sheepgrass chromosomes as probes to identify homologous/homeologous chromosomes 1–7. We found that the distributions and abundances of repetitive sequences, as well as the length and arm ratio, varied among homologous/homeologous chromosomes, providing direct cytogenetic evidence for the allotetraploid nature of sheepgrass. FISH-based karyotyping of different geographical accessions revealed substantial intraspecific variations in the chromosomal locations of repetitive DNA. Moreover, single-copy gene amplification was detected in sheepgrass, and chromosomal translocations were detected among the accessions. This study advances our understanding of sheepgrass genome structure and evolution through the establishment of a chromosome identification system integrated with wheat genetic maps.</p>

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Unambiguous chromosome identification by multicolour fluorescence in situ hybridisation reveals the genome organisation and evolution of sheepgrass (Leymus chinensis)

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年3月24日

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  • Meiping Sun,
  • Sihan Hu,
  • Tongtong Li,
  • Na Lv,
  • Jun Han,
  • Yang Li,
  • Jiabao Lu,
  • Zitong Wang,
  • Tengxin He,
  • Mengyuan Sun,
  • Zhi Qi,
  • Zhiyong Xiong,
  • Lei Wu

摘要

The unambiguous identification of individual chromosomes is fundamental to studying genome organisation and evolution. Sheepgrass (Leymus chinensis (Trin.) Tzvel), a perennial tetraploid grass closely related to wheat, is a valuable genetic resource for crop improvement. Here, we employed low-coverage sequencing and bioinformatics analysis to isolate and characterise a set of species-characteristic repetitive sequences in sheepgrass, including CL6, CL95, CL121, CL151, CL162, CL163, CL239, 5 S ribosomal DNA (rDNA), and 26 S rDNA. A multicolour fluorescence in situ hybridisation (FISH) assay using a probe cocktail targeting CL6, CL121, CL162, 5 S rDNA, and 26 S rDNA successfully distinguished all 28 sheepgrass chromosomes. On the basis of the close evolutionary relationship between wheat and sheepgrass, single-copy genes with known linkage map locations for wheat were applied to sheepgrass chromosomes as probes to identify homologous/homeologous chromosomes 1–7. We found that the distributions and abundances of repetitive sequences, as well as the length and arm ratio, varied among homologous/homeologous chromosomes, providing direct cytogenetic evidence for the allotetraploid nature of sheepgrass. FISH-based karyotyping of different geographical accessions revealed substantial intraspecific variations in the chromosomal locations of repetitive DNA. Moreover, single-copy gene amplification was detected in sheepgrass, and chromosomal translocations were detected among the accessions. This study advances our understanding of sheepgrass genome structure and evolution through the establishment of a chromosome identification system integrated with wheat genetic maps.