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利用基因编辑技术固定水稻杂种优势性状


利用杂种优势可以增加作物产量及综合农艺性状,然而后代性状的分离会使得优势表型丢失,因此杂交制种成为杂交品种应用的必需过程。通过无性繁殖可以将F1代的杂种优势进行固定。最近,中国水稻所王克剑团队利用CRISPR-Cas9基因编辑技术同时将水稻中的4个减数分裂和单倍体诱导相关基因进行突变,从而得到了可以无性繁殖的水稻植株,杂种优势性状得到固定并稳定遗传。


减数分裂是生物细胞中染色体数目减半的分裂方式。生殖细胞分裂时,染色体只复制一次,细胞连续分裂两次。PAIR1REC8 OSD1 三个基因是调控水稻减数分裂过程的重要基因,研究人员首先利用CRISPR-Cas9基因编辑技术将这3个基因同时突变,从而将植株的减数分裂过程转换成有丝分裂过程,因此植株配子基因型为二倍体,自交后代基因型为四倍体。


MTL基因是控制染色体加倍的磷脂酶基因,突变后水稻可以产生单倍体。因此,同时突变PAIR1REC8OSD1MTL四个基因后,水稻F1自交后代就成为与亲本基因型一致的二倍体植株。


研究人员在籼粳杂交稻品种春优84中进行了测试,结果表明,同时敲除四个基因后,F2植株表型性状与F1代植株十分相似,杂种优势性状得到固定并能够稳定遗传。

 

Nature Biotechnology, 04 January 2019

Clonal seeds from hybrid rice by simultaneous genome engineering of meiosis and fertilization genes


Author

Chun Wang, Qing Liu, Yi Shen, Yufeng Hua, Junjie Wang, Jianrong Lin, Mingguo Wu, Tingting Sun, Zhukuan Cheng, Raphael Mercier & Kejian Wang*

*: State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, China


Abstract

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 REC8PAIR1 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 (REC8PAIR1OSD1 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.

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