回交育种中供体基因组成分的分布及其应用(英文)

Distribution of Donor Genome Composition and Its Application in Marker Aided Backcrossing

推导了回交群体中供体基因组成分的条件概率分布，并用平均数预测各个体的供体染色体片段的大小。预测的精确度则用有关方差的公式，以供体的实际片断大小（ｙ）与根据标记基因型预测的供体片断大小（ｙｐ）的相关表示，并表达为标记密度的函数。结果表明：虽然在标记密度中等（例如 ４０ＣＭ／标记）时即能获得ｙ和ｙｐ的高度相关，但对一个大群体，仍必须通过高密度的标记图（例如 １０— ２０ｃＭ／标记）才可能鉴别出其中的最佳个体。因此，为了在标记辅助回交育种中充分利用标记信息，应当分步骤鉴定标记基因型和选择个体。这就是：先根据少数标记对所有个体作初步选择，再根据较多标记对少数个体作精细选择。这样，在基因渐渗实验中，就可以既提高对大群体的选择强度又只要鉴定有限数目的标记基因型。这是一种非常有效的方法。

Conditional distribution was derived for the genome composition given the marker genotype of individuals from a backcross population. Genome size from donor was predicted by the mean. The precision of the prediction, indicated by the correlation with the unknown actual genome size from donor, was formulated by the variance and expressed as a function of the marker density. Results indicated that although high correlation can be obtained with a moderate marker density, say 40 cM per marker, the best individual in a large population has to be identified through a map of high density, say 10 to 20 cM per marker. For the best use of marker information in a marker aided backcrossing program for gene introgression, a stepwise marker genotyping and individual selection were suggested. That is, a preliminary selection can be made among all individuals but only on a few markers for each individual, and a fine selection would then be made among a few individuals but on more markers for each individual. This would be a very efficient method to increase the selection intensity in a large population but with a manageable number of marker genotyping for a gene introgression experiment.