TAILIEUCHUNG - Báo cáo sinh học: " Dynamics of long-term genomic selection"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học quốc tế đề tài: Dynamics of long-term genomic selection | Jannink Genetics Selection Evolution 2010 42 35 http content 42 1 35 RESEARCH GSE Ge n et i cs Selection Evolution Open Access Dynamics of long-term genomic selection Jean-Luc Jannink1 2 Abstract Background Simulation and empirical studies of genomic selection GS show accuracies sufficient to generate rapid gains in early selection cycles. Beyond those cycles allele frequency changes recombination and inbreeding make analytical prediction of gain impossible. The impacts of GS on long-term gain should be studied prior to its implementation. Methods A simulation case-study of this issue was done for barley an inbred crop. On the basis of marker data on 192 breeding lines from an elite six-row spring barley program stochastic simulation was used to explore the effects of large or small initial training populations with heritabilities of or applying GS before or after phenotyping and applying additional weight on low-frequency favorable marker alleles. Genomic predictions were from ridge regression or a Bayesian analysis. Results Assuming that applying GS prior to phenotyping shortened breeding cycle time by 50 this practice strongly increased early selection gains but also caused the loss of many favorable QTL alleles leading to loss of genetic variance loss of GS accuracy and a low selection plateau. Placing additional weight on low-frequency favorable marker alleles however allowed GS to increase their frequency earlier on causing an initial increase in genetic variance. This dynamic led to higher long-term gain while mitigating losses in short-term gain. Weighted GS also increased the maintenance of marker polymorphism ensuring that QTL-marker linkage disequilibrium was higher than in unweighted GS. Conclusions Losing favorable alleles that are in weak linkage disequilibrium with markers is perhaps inevitable when using GS. Placing additional weight on low-frequency favorable alleles however may reduce the rate of loss of such alleles to

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