Occurrence of 2n gametes in the F1 hybrids of Oriental x Asiatic lilies (Lilium):: Relevance to intergenomic recombination and backcrossing
Occurrence of 2n gametes in the F1 hybrids of Oriental x Asiatic lilies (Lilium):: Relevance to intergenomic recombination and backcrossing
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DOI：
10.1007/s10681-005-2657-1
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发表时间：
2005-01-01
期刊：
影响因子：
1.9
通讯作者：
Van Tuyl, JM
中科院分区：
文献类型：
--
作者：
Barba-Gonzalez, R;Lim, KB;Van Tuyl, JM
对6个不同基因型的东方百合与亚洲百合（Lilium，2n = 2x = 24）杂种F-1的2n配子起源的细胞学模式进行了研究。亲本染色体组间的配对频率很低，平均为0.3 ~ 1.2个二价体/细胞。在某些情况下，在一个基因型内，二价体的频率从0到6不等。正常发生的单倍体花粉粒是完全不育的。与此相反，在不同的基因型，变量的2n花粉的百分比被发现，并显示为可育的估计从花粉萌发。使用基因组原位杂交（GISH）对中期I和减数分裂的后续阶段进行细胞学分析，发现外源基因组之间存在基因组间重组。在中期I阶段之后，三种不同类型的异常细胞学事件导致2n花粉的形成：（i）中期I后分裂（PMI），（ii）中期II后分裂（PMII）和（iii）花粉母细胞的不对称胞质分裂，随后是染色体分裂。所有三个细胞学事件导致第一次分裂恢复（FDR）配子。花粉离体萌发试验证明，两个基因型的2n花粉仅在开花第一天才有活力。利用2n花粉进行回交是可能的。2n花粉在BC 1后代基因组间重组的影响进行了讨论。
Cytological modes of the origin of 2n gametes were investigated in six different genotypes of F-1 hybrids between Oriental and Asiatic (OA) lilies (Lilium, 2n = 2x = 24). Chromosome pairing between the parental genomes was very low, the average frequency range from 0.3 to 1.2 bivalents per cell among the genotypes. Within a genotype the frequency of bivalents varied from 0 to 6 in some cases. The normally occurring haploid pollen grains were totally sterile. In contrast, in different genotypes, variable percentages of 2n pollen were found and shown to be fertile as estimated from pollen germination. A cytological analysis of Metaphase I and subsequent stages of meiosis using genomic in situ hybridization (GISH) revealed that there was intergenomic recombination between the alien genomes. Following Metaphase I stage, three different types of abnormal cytological events led to the formation of 2n pollen: (i) Post-Metaphase I division (PMI), (ii) Post-Metaphase II division (PMII) and (iii) Asymmetric Cytokinesis of the pollen mother cell followed by chromosome division. All three cytological events led to first division restitution (FDR) gametes. Based on in vitro pollen germination it was proved for two genotypes that 2n pollen was viable only during the first day of anthesis. It was possible to use 2n pollen successfully for backcrossing. Implications of 2n pollen for intergenomic recombination in BC1 progenies are discussed.