Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China.
State Key Laboratory of Tree Genetics and Breeding, Northeast Forestry University, Harbin 150040, China.
Int J Mol Sci. 2021 Oct 22;22(21):11424. doi: 10.3390/ijms222111424.
The molecular karyotype could represent the basic genetic make-up in a cell nucleus of an organism or species. A doubled haploid (DH) is a genotype formed from the chromosome doubling of haploid cells. In the present study, molecular karyotype analysis of the poplar hybrid () and the derived doubled haploids was carried out with labeled telomeres, rDNA, and two newly repetitive sequences as probes by fluorescence in situ hybridization (FISH). The tandem repeats, pPC349_XHY and pPD284_XHY, with high-sequence homology were used, and the results showed that they presented the colocalized distribution signal in chromosomes. For , pPD284_XHY produced hybridizations in chromosomes 1, 5, 8, and 9 in the hybrid. The combination of pPD284_XHY, 45S rDNA, and 5S rDNA distinctly distinguished six pairs of chromosomes, and the three pairs of chromosomes showed a significant difference in the hybridization between homologous chromosomes. The repeat probes used produced similar FISH hybridizations in the DH; nevertheless, pPD284_XHY generated an additional hybridization site in the telomere region of chromosome 14. Moreover, two pairs of chromosomes showed differential hybridization distributions between homologous chromosomes. Comparisons of the distinguished chromosomes between hybrid and DH poplar showed that three pairs of chromosomes in the DH presented hybridization patterns that varied from those of the hybrid. The No. 8 chromosome in DH and one of the homologous chromosomes in shared highly similar FISH patterns, which suggested the possibility of intact or mostly partial transfer of the chromosome between the hybrid and DH. Our study will contribute to understanding the genetic mechanism of chromosomal variation in and derived DH plants.
该分子核型可能代表生物体或物种细胞核的基本遗传构成。双单倍体（DH）是由单倍体细胞的染色体加倍形成的基因型。在本研究中，利用标记的端粒、rDNA 和两个新的重复序列作为探针，通过荧光原位杂交（FISH）对杨属杂种（）及其衍生的双单倍体进行了分子核型分析。串联重复序列 pPC349_XHY 和 pPD284_XHY 具有高度同源性，结果表明它们在染色体上呈现共定位分布信号。对于杂种，pPD284_XHY 在杂种的染色体 1、5、8 和 9 上产生杂交信号。pPD284_XHY 与 45S rDNA 和 5S rDNA 的组合明显区分了六对染色体，并且三对同源染色体在同源染色体之间的杂交中表现出明显差异。所用的重复探针在 DH 中产生了类似的 FISH 杂交；然而，pPD284_XHY 在染色体 14 的端粒区域产生了额外的杂交位点。此外，两对同源染色体之间的重复探针显示出不同的杂交分布。杂种和 DH 杨树区分的染色体比较表明，DH 中的三对染色体的杂交模式与杂种不同。DH 中的第 8 号染色体和杂种中的一条同源染色体表现出高度相似的 FISH 模式，这表明该染色体在杂种和 DH 之间可能存在完整或大部分部分转移的可能性。我们的研究将有助于理解和衍生的 DH 植物中染色体变异的遗传机制。
