中国科学院植物研究所焦远年小组揭示小麦祖先基因组重建及染色体重排的演化。2025年1月1日，《遗传学报》在线发表了这项成果。

研究人员通过重建小麦（Triticeae）最近共同祖先（MRCA）和小麦谱系（小麦和山羊草属）最近共同祖先的高质量祖先基因组，深入探讨小麦属染色体重排的演化过程。小麦MRCA的原始基因（protogene）数为22894个，而小麦谱系MRCA的原始基因数为29060个，这些基因排列在它们的祖先顺序中。通过将现代小麦染色体划分为同源区块，并将每个同源区块与相应的原始染色体连接，研究人员重新审视了黑麦染色体的结构演化，并提出了不同的演化路径。

研究人员发现之前识别出的黑麦和乌拉尔图小麦（Triticum urartu）中的4L/5L互换易位事件是独立发生的，且不太可能是远缘杂交后染色体内因杂交引起的基因转移。研究人员还澄清了四倍体小麦中的4AL/7BS易位事件是双向而非单向的转位事件。

最后，研究人员在原始染色体中识别了多个断裂点，这些断裂点在小麦演化过程中独立出现，可能是潜在的染色体重排热点。该研究表明，这些重建的祖先基因组可以作为特殊的比较参考，有助于深入理解小麦染色体结构重排的演化机制。

研究人员表示，染色体重排常常导致表型变异。尽管在小麦中已识别出若干主要的染色体重排事件，但对这些重排的顺序、时间以及断裂点的全面研究尚未进行。

附：英文原文

Title: Ancestral genome reconstruction and the evolution of chromosomal rearrangements in Triticeae

Author: Yuannian Jiao a b c

Issue&Volume: 2025/01/01

Abstract: Chromosomal rearrangements (CRs) often cause phenotypic variations. Although several major rearrangements have been identified in Triticeae, a comprehensive study of the order, timing, and breakpoints of CRs has not been conducted. Here, we reconstruct high-quality ancestral genomes for the most recent common ancestor (MRCA) of the Triticeae, and the MRCA of the wheat lineage (Triticum and Aegilops). The protogenes of MRCA of the Triticeae and the wheat lineage are 22,894 and 29,060, respectively, which were arranged in their ancestral order. By partitioning modern Triticeae chromosomes into sets of syntenic regions and linking each to the corresponding protochromosomes, we revisit the rye chromosome structural evolution and propose alternative evolutionary routes. The previously identified 4L/5L reciprocal translocation in rye and Triticum urartu are found to have occurred independently and are unlikely the result of chromosomal introgression following distant hybridization. We also clarify that the 4AL/7BS translocation in tetraploid wheat was a bidirectional rather than unidirectional translocation event. Lastly, we identify several breakpoints in protochromosomes that independently reoccur following Triticeae evolution, representing potential CR hotspots. This study demonstrates that these reconstructed ancestral genomes can serve as special comparative references and facilitate a better understanding of the evolution of structural rearrangements in Triticeae.

DOI: 10.1016/j.jgg.2024.12.017

Source: https://www.sciencedirect.com/science/article/abs/pii/S1673852724003709