Li Xiang, Meng Dexuan, Chen Shaojiang, Luo Haishan, Zhang Qinghua, Jin Weiwei, Yan Jianbing
National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, China.
National Maize Improvement Center of China, Beijing Key Laboratory of Crop Genetic Improvement, Key Laboratory of Crop Heterosis and Utilization, Ministry of Education (MOE), China Agricultural University, Beijing, 100193, China.
Nat Commun. 2017 Oct 23;8(1):991. doi: 10.1038/s41467-017-00969-8.
Production of maternal haploids using a conspecific haploid inducer is routine and highly efficient in maize. However, the underlying mechanism of haploid induction (HI) is unclear. We develop a method to isolate three nuclei from a pollen grain and four microspores from a tetrad for whole-genome sequencing. A high rate of aneuploidy is observed at the three-nucleus stage (6/22 pollens) rather than at the tetrad stage (1/72 microspores) in one HI line CAU5. Frequent aneuploidy is also observed in another two inducer lines, but not in two regular lines, which implies that HI may be associated with pollen aneuploidy. We further sequence the individual embryos and endosperms of 88 maize kernels crossing between regular and inducer lines. Genome-wide elimination of the CAU5-derived chromosome is identified in eight of 81 embryos. Together, these results suggest that continuous chromosome fragmentation occurring post meiosis in the gametophyte may cause haploidy of the embryo.
利用同种单倍体诱导系产生母本单倍体在玉米中是常规且高效的。然而，单倍体诱导（HI）的潜在机制尚不清楚。我们开发了一种方法，从花粉粒中分离出三个细胞核，从四分体中分离出四个小孢子用于全基因组测序。在一个HI系CAU5中，在三核期（6/22花粉）观察到较高的非整倍体率，而在四分体期（1/72小孢子）未观察到。在另外两个诱导系中也观察到频繁的非整倍体现象，但在两个常规系中未观察到，这表明HI可能与花粉非整倍体有关。我们进一步对88个常规系与诱导系杂交的玉米籽粒的单个胚和胚乳进行测序。在81个胚中的8个中鉴定出全基因组范围内CAU5来源染色体的消除。总之，这些结果表明，配子体减数分裂后发生的连续染色体片段化可能导致胚的单倍体化。
