Key Laboratory of Crop Gene Resources and Germplasm Enhancement, MOA, the National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, CAAS, Beijing, 100081, China.
Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100101, China.
Sci Rep. 2017 Mar 22;7:44530. doi: 10.1038/srep44530.
Selection is one of the most important forces in crop evolution. Common wheat is a major world food crop and a typical allopolyploid with a huge and complex genome. We applied four approaches to detect loci selected in wheat during domestication and improvement. A total of 7,984 candidate loci were detected, accounting for 23.3% of all 34,317 SNPs analysed, a much higher proportion than estimated in previous reports. We constructed a first generation wheat selection map which revealed the following new insights on genome-wide selection: (1) diversifying selection acted by increasing, decreasing or not affecting gene frequencies; (2) the number of loci under selection during domestication was much higher than that during improvement; (3) the contribution to wheat improvement by the D sub-genome was relatively small due to the bottleneck of hexaploidisation and diversity can be expanded by using synthetic wheat and introgression lines; and (4) clustered selection regions occur throughout the wheat genome, including the centromere regions. This study will not only help future wheat breeding and evolutionary studies, but will also accelerate study of other crops, especially polyploids.
选择是作物进化过程中最重要的力量之一。普通小麦是世界主要的粮食作物，也是一种典型的异源多倍体，具有庞大而复杂的基因组。我们应用了四种方法来检测小麦在驯化和改良过程中选择的基因座。共检测到 7984 个候选基因座，占分析的 34317 个 SNP 的 23.3%，这一比例远高于之前的估计。我们构建了第一代小麦选择图谱，揭示了基因组范围内选择的以下新见解：（1）通过增加、减少或不影响基因频率的多样化选择；（2）驯化过程中选择的基因座数量远高于改良过程中的数量；（3）由于六倍体化的瓶颈，D 亚基因组对小麦改良的贡献相对较小，并且可以通过使用合成小麦和导入系来扩大多样性；（4）选择区域在整个小麦基因组中聚集，包括着丝粒区域。这项研究不仅将有助于未来的小麦育种和进化研究，也将加速其他作物，特别是多倍体作物的研究。
