Author
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Tamulonis, John |
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Cregan, Perry |
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Submitted to: BARC Poster Day
Publication Type: Abstract Only Publication Acceptance Date: 2/3/1997 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Wheat (Triticum aestivum L. em. Thell.) is the world's leading cereal grain and most important food crop. Wheat is hexaploid with 2n = 6x = 42 with three distinct genomes (A, B, and D). Wheat has a large genome comprised of 16 billion base pairs. With RFLP markers the level of intraspecific polymorphism in hexaploid wheat is low (3-9%). We are developing a PCR based, simple sequence repeat (SSR) marker system that will exploit the inherent variation in wheat. Genomic DNA of Catoctin' hexaploid wheat was digested with RsaI. Fragments in the 500-700 b.p. range were cloned into a plasmid vector that was used to transform E. coli. Colonies were stamped onto nitrocellulose membranes and were hybridized to 32P labeled oligonucleotide probes to identify clones containing (AG)n, (AC)n, and (ATT)n microsatellites. Eighty-nine clones were sequenced and microsatellites identified. About 95% of the clones sequenced contained SSRs. Of the primer pairs synthesized, 30% produced a single PCR product with the predicted molecular weight. The primers amplify single locus products that were genome specific. Based on preliminary data (eight SSR loci tested on seven genotypes), the number of alleles per locus was 3.5 with an average polymorphism information content (PIC) of 0.62. The average dinucleotide repeat number (AG/TC or AC/TG) at these eight loci was 13.4 and the predominant repeat motif was AG/TC. Because SSR markers are PCR-based they are amenable to automated detection systems, and have wide applicability in genetic mapping and marker-facilitated plant improvement. |
