QTL精细定位影响因素的数学模型.doc

QTL精细定位的数学模型 李梦，林飞，章元明 （南京农业大学作物遗传与种质创新国家重点实验室国家大豆改良中心，南京210095） athematical Model in Fine Mapping of Quantitative Trait Locus LI Meng, LIN Fei, HUANG Ju, ZHANG Yuan-ming (State Key Laboratory of Crop Genetics and Germplasm Enhancement and National Center for Soybean Improvement, Nanjing Agricultural University, Nanjing 210095) Abstract: 【Objective】A segregating population derived from the cross between two isogenic lines of a targeted quantitative trait locus (QTL) may be used to fine map QTL. The inheritance analysis methods for qualitative traits are available if the QTL effect is large, and if this is not the case, those for quantitative traits should be adopted. For the latter, there are some impact factors, i.e., sample size, marker density and QTL heritability. Therefore, it is necessary to study their effects on fine mapping of QTL. 【Method】Backcross, recombinant inbred line and double haploid populations derived from the cross between two isogenic lines of a targeted QTL under various sample sizes, marker densities and QTL heritabilities were simulated and used to detect QTL. One-LOD (logarithm of odds) interval length for QTL position is used to indicate the precision of QTL mapping. Nonlinear regression of the length on the three factors mentioned above is fitted. 【Result】 Results show that the sample size, marker density and QTL heritability affect the precision of QTL mapping, and the new model in this paper, including marker density variable, is better than Darvasi and Soller model that does not consider marker density variable.【Conclusion】This model could provide more theoretical guide for fine mapping of QTL. Key words: Quantitative trait locus; Fine mapping; Monte Carlo simulation; Nonlinear regression 0 引言 Sax的种皮色与种子大小连锁分析定位数量性状基因[1]，分子标记连锁图的出现[2]和区间作图法[3]的提出。但是，10～30 cM初定位精度降低了标记辅助选择的功效，也不能实施QTL克隆。精细定位QTL。目前，QTL精细定位的途径有：发展新的统计分析方法[5~7]、增加重组机会[8~10]和利用次级分离群体[11]。利用单QTL近等基因系构建分离群体以精细定位QTL是常用的方法[11~14]。当QTL效应较大时，目标数量性状可被当作质