Dissertation
Identification of quantitative trait loci linked markers and characterization of positional candidate genes for beef marbling in Wagyu x Limousin F2 crosses
Washington State University
Doctor of Philosophy (PhD), Washington State University
05/2006
DOI:
https://doi.org/10.7273/000005630
Abstract
Selection for marbling has been recognized as an important objective for the production of high quality beef worldwide. The objective of this study is to identify genes or markers that are associated with beef marbling. In experiment 1, we presented a simplified approach for screening and mapping of QTL linked markers for beef marbling using a Wagyu x Limousin F2 reference population. This simplified approach involves integration of the amplified fragment length polymorphism (AFLP) with DNA pooling and selective genotyping and comparative bioinformatics tools. AFLP analysis yielded four AFLP markers. Sequencing and in silico characterization assigned two of these AFLP markers to bovine chromosomes 13 (BTA13) and 1 (BTA1), which are orthologous to human chromosomes HSA10p11.23 and HSA21q22.2 with both regions harboring QTL for obesity-related phenotypes. Both AFLP markers showed significantly large additive genetic effects on beef marbling score (BMS). Overall, this approach is less expensive and less time consuming than current QTL mapping approaches.; In particular, this approach is suitable for screening and mapping QTL linked markers when targeting one or a few complex traits. In experiment 2, we identified one candidate gene of poly (A) polymerase associated domain containing 1 (PAPD1) associated with beef marbling. This gene is in close proximity to the human gene KIAA1462 which is orthologous to the AFLP marker located on BTA13 revealed in experiment 1. PAPD1 gene is a newly identified mitochondrial gene that encodes polymerase required for the polyadenylation and stability of mammalian mitochondrial mRNAs. Ten genetic markers were detected in the promoter and exon 1 region of PAPD1 gene. Among seven markers assayed on 246 Wagyu x Limousin F2 animals, two single nucleotide polymorphisms (SNPs) in the promoter region were significantly associated with BMS. However, there was a significant interaction between a third SNP, which causes amino acid changes derived from coding exon 1, and each of these two promoter SNPs on BMS. In particular, the differences between double heterozygous animals and other genotypes animals were from 0.67 to 2.3 standard deviations for the trait in both cases. Our study provides evidence for a new mechanism the compound heterosis involved in extreme obesity, which warrants further examination.
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Details
- Title
- Identification of quantitative trait loci linked markers and characterization of positional candidate genes for beef marbling in Wagyu x Limousin F2 crosses
- Creators
- Qianjun Xiao
- Contributors
- Zhihua Jiang (Chair)Jerry J Reeves (Committee Member)Gary H Thorgaard (Committee Member) - Washington State University, School of Biological SciencesJan Roger Busboom (Committee Member) - Washington State University, Department of Animal Sciences
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Animal Sciences
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 117
- Identifiers
- 99901054737701842
- Language
- English
- Resource Type
- Dissertation