Zeng Yibing, Wang Mingyu, Gent Jonathan I, Dawe R Kelly
Department of Genetics, University of Georgia, Athens, GA 30602, USA.
Institute of Bioinformatics, University of Georgia, Athens, GA 30602 USA.
Sci Adv. 2025 May 23;11(21):eadw3433. doi: 10.1126/sciadv.adw3433. Epub 2025 May 21.
Activation of synthetic centromeres on chromosome 4 in maize leads to its breakage and formation of trisomic fragments called neochromosomes. A limitation of neochromosomes is their low and unpredictable transmission rates due to trisomy. Here, we report that selecting for dicentric recombinants through male crosses uncovers stabilized chromosome 4 fission events, which split it into 4a-4b complementary chromosome pairs, where 4a carries a native centromere and 4b carries a synthetic one. The cells rapidly stabilized chromosome ends by de novo telomere formation, and the new centromeres spread among genes without altering their expression. When both 4a and 4b chromosomes were made homozygous, they segregated through meiosis indistinguishably from wild type and gave rise to healthy plants with normal seed set, indicating that the synthetic centromere was fully functional. This work leverages synthetic centromeres to engineer chromosome fission, raising the diploid chromosome number of maize from 20 to 22.
玉米4号染色体上合成着丝粒的激活导致其断裂并形成称为新染色体的三体片段。新染色体的一个局限性是由于三体性导致其传递率低且不可预测。在这里，我们报告通过雄性杂交选择双着丝粒重组体揭示了稳定的4号染色体裂变事件，该事件将其分裂为4a - 4b互补染色体对，其中4a携带一个天然着丝粒，4b携带一个合成着丝粒。细胞通过从头形成端粒迅速稳定染色体末端，新着丝粒在基因间扩散而不改变它们的表达。当4a和4b染色体都纯合时，它们在减数分裂中的分离与野生型无明显差异，并产生具有正常结实率的健康植株，表明合成着丝粒功能完全正常。这项工作利用合成着丝粒来设计染色体裂变，将玉米的二倍体染色体数从20增加到22。
