School of Integrative Plant Science, Cornell University, Ithaca, NY 14853.
Proc Natl Acad Sci U S A. 2023 Apr 4;120(14):e2205785119. doi: 10.1073/pnas.2205785119. Epub 2023 Mar 27.
Plant breeding relies on crossing-over to create novel combinations of alleles needed to confer increased productivity and other desired traits in new varieties. However, crossover (CO) events are rare, as usually only one or two of them occur per chromosome in each generation. In addition, COs are not distributed evenly along chromosomes. In plants with large genomes, which includes most crops, COs are predominantly formed close to chromosome ends, and there are few COs in the large chromosome swaths around centromeres. This situation has created interest in engineering CO landscape to improve breeding efficiency. Methods have been developed to boost COs globally by altering expression of anti-recombination genes and increase CO rates in certain chromosome parts by changing DNA methylation patterns. In addition, progress is being made to devise methods to target COs to specific chromosome sites. We review these approaches and examine using simulations whether they indeed have the capacity to improve efficiency of breeding programs. We found that the current methods to alter CO landscape can produce enough benefits for breeding programs to be attractive. They can increase genetic gain in recurrent selection and significantly decrease linkage drag around donor loci in schemes to introgress a trait from unimproved germplasm to an elite line. Methods to target COs to specific genome sites were also found to provide advantage when introgressing a chromosome segment harboring a desirable quantitative trait loci. We recommend avenues for future research to facilitate implementation of these methods in breeding programs.
植物育种依赖于交叉来创造新的等位基因组合，以赋予新品种更高的生产力和其他所需的特性。然而，交叉（CO）事件很少见，因为通常在每一代的每条染色体上只发生一个或两个 CO。此外，CO 不是沿着染色体均匀分布的。在基因组较大的植物中，包括大多数作物，CO 主要形成在染色体末端附近，而在着丝粒周围的大染色体区域中 CO 很少。这种情况引起了人们对工程 CO 景观以提高育种效率的兴趣。已经开发了一些方法来通过改变抗重组基因的表达来提高 CO 的全局发生率，并通过改变 DNA 甲基化模式来增加某些染色体部分的 CO 率。此外，还在努力设计将 CO 靶向特定染色体位点的方法。我们回顾了这些方法，并通过模拟检查它们是否确实有能力提高育种计划的效率。我们发现，改变 CO 景观的当前方法可以为育种计划带来足够的好处，具有吸引力。它们可以增加轮回选择中的遗传增益，并显著减少供体基因座周围的连锁拖曳，以将一个性状从未改良的种质中引入到一个优良品系中。还发现，将 CO 靶向特定基因组位点的方法在引入含有理想数量性状位点的染色体片段时也具有优势。我们为未来的研究推荐了一些途径，以促进这些方法在育种计划中的实施。
