Genome composition changes due to long term selection by soybean breeders

大豆品种的持续改进依赖于亲本之间足够的遗传变异，以产生一个个体群体，其中有足够的表型变异来改善感兴趣的性状。由于表型变异与遗传多样性呈正相关（Moose and Mumm 2008），因此对于大豆育种计划来说，保持足够的遗传多样性水平以持续获得特定性状的遗传增益是很重要的。此外，开发适合利基市场的大豆品种是加拿大大豆育种者的一个重要目标。这就要求种质资源不仅在产量等性状上具有遗传多样性，而且在食品级特性或营养化合物等增值性状上也具有遗传多样性。基因组技术的最新进展使研究一个物种的全基因组变化具有前所未有的能力。通过将这些技术应用于育种计划的系谱，可以研究由于长期育种者选择而导致的大豆基因组的具体变化。首先，通过对一个谱系的成员进行基因分型，遗传多样性在几代育种活动中的变化可以被表征。其次，染色体的传递可以被跟踪，等位基因组成的变化和选择周期可以被确定。

Continued improvement of soybean varieties relies on sufficient genetic variation between parents to produce a population of individuals in which there is enough phenotypic variation to improve traits of interest. As phenotypic variation is positively associated with genetic diversity (Moose and Mumm 2008) it is important for a soybean breeding program to maintain a sufficient level of genetic diversity for continued genetic gain of a particular trait. In addition, developing soybean varieties for niche markets is an important objective for Canadian soybean breeders. This requires germplasm sources to have genetic diversity not only for traits such as yield, but also value-added traits such as food grade properties or nutraceutical compounds. The recent advancements in genomic technologies allow for unprecedented capabilities when investigating whole-genome changes to a species. By applying these technologies to pedigrees of a breeding program, the specific changes in the soybean genome due to long-term breeder selection can be studied. First, by genotyping the members of a pedigree, the changes in genetic diversity over generations of breeding activity can be characterized. Secondly, the transmission of chromosomes can be tracked and changes in allelic composition over generations and selection cycles can be determined.