Genetic diversity and linkage disequilibrium studies on a 3.1-Mb genomic region of chromosome 3B in European and Asian bread wheat (Triticum aestivum L.) populations |
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Authors: | C Y Hao M R Perretant F Choulet L F Wang E Paux P Sourdille X Y Zhang C Feuillet Francois Balfourier |
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Institution: | (1) INRA UMR 1095, Genetics Diversity and Ecophysiology of Cereals, 234 Avenue du Brezet, 63100 Clermont-Ferrand, France;(2) Key Laboratory of Crop Germplasm Resources and Utilization, Ministry of Agriculture, CAAS, Beijing, 100081, China;(3) The National Key Facility for Crop Gene Resources and Genetic Improvement, CAAS, Beijing, 100081, China;(4) Institute of Crop Science, CAAS, Beijing, 100081, China; |
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Abstract: | Genetic diversity and linkage disequilibrium (LD) were investigated in 376 Asian and European accessions of bread wheat (Triticum aestivum L.). After a first and rapid screening about diversity and genetic structure at the whole genome scale using 70 simple sequence
repeats (SSRs), we focused on a sequenced contig (ctg954) of 3.1 Mb located on the short arm of chromosome 3B of cv. Chinese Spring, using 32 SSRs and 10 single nucleotide polymorphisms.
This contig is part of a multiple fungal resistance region. Mean polymorphism information content value on the 32 SSRs was
slightly higher in the Asian genepool (0.396) than that for the European (0.329) pool. Compared with results at the whole
genome scale, data from this 3.1-Mb region indicated similar trends in genetic diversity indices between both genepools. Population
structure and molecular variance analyses demonstrated significant genetic differentiation and geographical subdivision in
both groups of accessions. Concerning LD at the contig level, the European population had a significantly higher mean r
2 value (0.23) than the Asian population (0.18), indicating a stronger LD in the European material. With a mean of 1 marker
every 74 kb, the resolution reached here allowed to perform a detailed comparative analysis of the LD and genetic diversity
along the complete 3.1-Mb region in both genepools. A sliding-window approach revealed some interesting regions of the contig
where LD is increasing when genetic diversity is decreasing. This study provides an in-depth understanding of molecular population
genetics in European and Asian wheat gene pools, and prospects for association mapping of important sources of fungal disease
resistance. |
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