Hua Yu-Wei, Liu Min, Li Zai-Yun
National Key Laboratory of Crop Genetic Improvement, National Center of Crop Molecular Breeding Technology, National Center of Oil Crop Improvement Wuhan, Huazhong Agricultural University, Wuhan 430070, China.
Ann Bot. 2006 Jun;97(6):993-8. doi: 10.1093/aob/mcl073. Epub 2006 Apr 19.
The phenomenon of parental genome separation during the mitotic divisions of hybrid cells was proposed to occur under genetic control in intergeneric hybrids between cultivated Brassica species and Orychophragmus violaceus (2n = 24). To elucidate further the cytological and molecular mechanisms behind parental genome separation, Brassica carinata (2n = 34) x O. violaceus hybrids were resynthesized and their chromosome/genomic complements analysed.
F(1) hybrids of the cross were obtained following embryo rescue, and were investigated for their cytological behaviour and subjected to genomic in situ hybridization (GISH) and amplified fragment length polymorphism (AFLP) to determine the contribution of parental genomes.
All the F(1) plants with high fertility closely resembled B. carinata in morphological attributes. These were mixoploids with 2n chromosome numbers ranging from 17 to 35; however, 34, the same number as in B. carinata, was the most frequent number of chromosomes in ovary and pollen mother cells (PMCs). GISH clearly identified 16 chromosomes of B. nigra in ovary cells and PMCs with 2n = 34 and 35. However, no O. violaceus chromosome was detected, indicating the presence of the intact B. carinata genome and elimination of the entire O. violaceus genome. However, some AFLP bands specific for O. violaceus and novel for the two parents were detected in the leaves. Cells with fewer than 34 chromosomes had lost some B. oleracea chromosomes. F(2) plants were predominantly like B. carinata, but some contained O. violaceus characters.
The cytological mechanism for the results involves complete and partial genome separation at mitosis in embryos of F(1) plants followed by chromosome doubling, elimination of cells with O. violaceus chromosomes and some introgression of O. violaceus genetic information.
有人提出，在栽培芸苔属物种与诸葛菜（2n = 24）的属间杂种的有丝分裂过程中，亲本基因组分离现象是在遗传控制下发生的。为了进一步阐明亲本基因组分离背后的细胞学和分子机制，重新合成了埃塞俄比亚芥（2n = 34）×诸葛菜杂种，并对其染色体/基因组组成进行了分析。
通过胚胎拯救获得了该杂交组合的F(1)杂种，研究了它们的细胞学行为，并进行了基因组原位杂交（GISH）和扩增片段长度多态性（AFLP）分析，以确定亲本基因组的贡献。
所有高育性的F(1)植株在形态特征上与埃塞俄比亚芥极为相似。这些植株为混倍体，2n染色体数在17至35之间；然而，34（与埃塞俄比亚芥的染色体数相同）是子房和花粉母细胞（PMC）中最常见的染色体数。GISH清楚地在2n = 34和35的子房细胞和PMC中鉴定出16条黑芥染色体。然而，未检测到诸葛菜染色体，这表明存在完整的埃塞俄比亚芥基因组，且整个诸葛菜基因组已被消除。然而，在叶片中检测到了一些诸葛菜特有的、双亲均没有的AFLP条带。染色体数少于34条的细胞丢失了一些甘蓝染色体。F(2)植株主要与埃塞俄比亚芥相似，但有些具有诸葛菜的特征。
该结果的细胞学机制涉及F(1)植株胚胎有丝分裂时的全基因组和部分基因组分离，随后染色体加倍，消除含有诸葛菜染色体的细胞，以及诸葛菜遗传信息的一些渗入。
