A high-density transcript linkage map of barley derived from a single population.

Area of Science:

• Genomics
• Plant Science
• Molecular Biology

Background:

• Developing high-resolution genetic maps is crucial for understanding plant genomes and facilitating marker-assisted breeding.
• Existing genetic resources for barley (Hordeum vulgare) require expansion to support comprehensive genomic studies.
• Expressed Sequence Tags (ESTs) provide valuable gene-anchored markers for genetic mapping.

Purpose of the Study:

• To construct a high-resolution transcript linkage map of barley using a single doubled haploid (DH) population.
• To identify and map single nucleotide polymorphisms (SNPs), cleaved amplified polymorphic sequences (CAPS), and insertions/deletions (INDELs) derived from 3'-end ESTs.
• To compare mapped barley ESTs with other plant genomes, particularly wheat and rice, to identify conserved genomic regions.

Main Methods:

• Utilized a DH mapping population derived from a cross between barley cultivar 'Haruna Nijo' and wild-form accession 'H602'.
• Developed and screened 10,366 primer sets from 3' EST sequences for polymorphisms.
• Mapped polymorphic markers (SNPs, CAPS, INDELs) to construct the linkage map.

Main Results:

• Successfully mapped 2890 expressed sequence tags (ESTs), representing approximately 9% of barley genes.
• Identified 3975 polymorphic markers from 7700 useful amplicons, with 2890 mapped using SNPs, CAPS, and INDELs.
• Observed significant sequence similarity between mapped barley ESTs and wheat (93%) and rice (50%), indicating conserved synteny, especially between barley chromosome 3H and rice chromosome 1.

Conclusions:

• The developed high-resolution transcript linkage map provides a valuable genetic resource for barley gene cloning and trait analysis.
• The map facilitates the identification of genes controlling simple and complex traits, aiding in barley improvement.
• The findings contribute to the physical mapping framework for barley, essential for future genome sequencing initiatives.