Heterosis, or hybrid vigor, is exploited by breeders to produce elite high-yielding crop lines, but beneficial phenotypes are lost in subsequent generations owing to genetic segregation. Clonal propagation through seeds would enable self-propagation of F₁ hybrids. Here we report a strategy to enable clonal reproduction of F₁ rice hybrids through seeds. We fixed the heterozygosity of F₁ hybrid rice by multiplex CRISPR-Cas9 genome editing of the REC8, PAIR1 and OSD1 meiotic genes to produce clonal diploid gametes and tetraploid seeds. Next, we demonstrated that editing the MATRILINEAL (MTL) gene (involved in fertilization) could induce formation of haploid seeds in hybrid rice. Finally, we combined fixation of heterozygosity and haploid induction by simultaneous editing of all four genes (REC8, PAIR1, OSD1 and MTL) in hybrid rice and obtained plants that could propagate clonally through seeds. Application of our method may enable self-propagation of a broad range of elite F₁ hybrid crops.

中文翻译：

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通过减数分裂和受精基因同步基因组工程从杂交水稻获得克隆种子。

育种者利用杂种优势或杂种优势来产生优良的高产农作物，但由于遗传分离，有益的表型在后代中消失了。通过种子的克隆繁殖将使F ₁杂种能够自我繁殖。在这里，我们报告了一种通过种子实现F ₁水稻杂交种无性繁殖的策略。我们固定了F ₁的杂合性通过对REC8，PAIR1和OSD1减数分裂基因进行多重CRISPR-Cas9基因组编辑来产生杂交水稻，以产生克隆二倍体配子和四倍体种子。接下来，我们证明了编辑MATRILINEAL（MTL）基因（涉及施肥）可以诱导杂交水稻中单倍体种子的形成。最后，我们通过同时编辑杂交水稻中的所有四个基因（REC8，PAIR1，OSD1和MTL），将杂合性固定和单倍体诱导结合在一起，获得了可以通过种子克隆繁殖的植物。应用我们的方法可以使多种优良的F ₁杂种作物进行自我繁殖。