著絲粒是確保細(xì)胞分裂時(shí)染色體能夠被精準(zhǔn)、均等地分配到子細(xì)胞中的核心結(jié)構(gòu)。盡管其功能在所有真核生物中高度保守，著絲粒DNA序列卻是基因組中進(jìn)化最迅速的部分之一，這一現(xiàn)象被稱為“著絲粒悖論”。在多倍體植物中，這一悖論顯得尤為復(fù)雜。多倍體植物的細(xì)胞核內(nèi)，匯集了來自不同祖先物種的染色體組，它們的著絲粒被迫在同一個(gè)細(xì)胞核環(huán)境中共同工作和演化。這些來自不同“家鄉(xiāng)”的著絲粒是如何在多倍化這一劇烈的基因組事件后相互適應(yīng)、協(xié)同進(jìn)化的？它們的演化遵循著怎樣的規(guī)律？這些問題一直是基因組進(jìn)化生物學(xué)領(lǐng)域的謎團(tuán)。

　　

　　普通小麥擁有清晰的、階梯式的多倍化歷史，是研究這一科學(xué)問題的絕佳模型。本研究通過整合多物種、多倍性水平的基因組和表觀基因組數(shù)據(jù)，系統(tǒng)揭示了異源多倍體小麥中不同亞基因組著絲粒的演化“命運(yùn)”大相徑庭（如圖）。研究發(fā)現(xiàn)，小麥著絲粒的演化主要由著絲粒特異性逆轉(zhuǎn)錄轉(zhuǎn)座子（CRWs）驅(qū)動(dòng)，但不同亞基因組采取了不同的演化策略：AA亞基因組通過新CRW家族的不斷“入侵”和對(duì)舊序列的“替換”來進(jìn)行動(dòng)態(tài)重塑；而DD亞基因組則通過向側(cè)翼區(qū)域的“擴(kuò)張”來適應(yīng)新的核環(huán)境，且這一過程是漸進(jìn)的。這項(xiàng)工作不僅為理解復(fù)雜基因組中著絲粒的演化和維持機(jī)制提供了見解，也展現(xiàn)了多倍化后基因組內(nèi)部不同組分如何通過差異化的路徑實(shí)現(xiàn)協(xié)同演化。這些發(fā)現(xiàn)為利用遠(yuǎn)緣雜交進(jìn)行小麥遺傳改良提供了理論基礎(chǔ)，有助于更好地理解和預(yù)測雜交后代基因組的穩(wěn)定性和演化動(dòng)態(tài)。

　　

　　華中農(nóng)業(yè)大學(xué)作物遺傳改良全國重點(diǎn)實(shí)驗(yàn)室博士后黃宇虹、中國科學(xué)院遺傳發(fā)育所劉陽副研究員與劉暢博士為論文共同第一作者，華中農(nóng)業(yè)大學(xué)作物遺傳改良全國重點(diǎn)實(shí)驗(yàn)室、湖北洪山實(shí)驗(yàn)室蘇漢東教授與中國科學(xué)院遺傳發(fā)育所韓方普研究員為論文共同通訊作者。該研究得到國家重點(diǎn)研發(fā)計(jì)劃和國家自然科學(xué)基金等項(xiàng)目資助。

　　

　　論文鏈接：https://genomebiology.biomedcentral.com/articles/10.1186/s13059-025-03759-4

　　

　　英文摘要：

　　

　　Background：Centromeres are crucial for precise chromosome segregation and maintaining genome stability during cell division. However, their evolutionary dynamics, particularly in polyploid organisms with complex genomic architectures, remain largely enigmatic. Allopolyploid wheat, with its well-defined hierarchical ploidy series and recent polyploidization history, serves as an excellent model to explore centromere evolution.

　　

　　Results：In this study, we perform a systematic comparative analysis of centromeres in common wheat and its corresponding ancestral species, utilizing the latest comprehensive reference genome assembly available. Our findings reveal that wheat centromeres predominantly consist of five types of centromeric-specific retrotransposon elements (CRWs), with CRW1 and CRW2 being the most prevalent. We identify distinct evolutionary trajectories in the functional centromeres of each subgenome, characterized by variations in copy number, insertion age, and CRW composition. By utilizing CENH3-ChIP data across various ploidy levels, we uncover a series of CRW invasion events that have shaped the evolution of AA subgenome centromeres. Conversely, the evolutionary process of the DD subgenome centromeres involves their expansion from diploid to hexaploid wheat, facilitating adaptation to a larger genomic context. Integration of complete einkorn centromere assemblies and Aegilops tauschii pan-genomes further revealed subgenome-specific centromere evolutionary trajectories. By inclusion of synthetic hexaploid from S2-S3 generations, alongside 2x/6 × natural accessions, we demonstrate that DD subgenome centromere expansion represents a gradual evolutionary process rather than an immediate response to polyploidization.

　　

　　Conclusions：Our study provides a comprehensive landscape of centromere adaptation, evolution, and maturation, along with insights into how retrotransposon invasions drive centromere evolution in polyploid wheat.