Molecular Karyotyping on Populus simonii × P. nigra and the Derived Doubled Haploid

Abstract

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 Populus simonii × P. nigra (P. xiaohei) 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 P. xiaohei, 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 P. xiaohei 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 P. xiaohei and derived DH plants.

Evaluation of the evolutionary process within Populus caspica species from Hyrcanian forests by karyotype analysis

“…By chromosome painting probes they demonstrated that no chromosomal rearrangements on any of the 19 chromosomes among some species of Populus including P. euphratica and P. deltoids have occurred. On the other hand, the potential for intact or largely partial chromosome transfer between poplar hybrids has been proposed by Liu et al (2021) using labeled telomeres, rDNA, and repetitive sequences as probes, that supports the findings in the present study.…”

“…Other karyological studies showed that in Populus genus, with a basic haploid chromosome number of 19, diploidy is predominant. Due to the small chromosomes, karyotype information has been reported for several Populus species (Islam-Faridi et al 2009;Liu et al 2021). Hence, in recent years fluorescence in situ hybridization (FISH) has been employed for identifying chromosomes in poplars to compare the karyotype and similarity of chromosome structure among different species (Xin et al 2020;Kim et al 2020).…”

Exceptionally high genetic variance of the doubled haploid (DH) population of poplar

“…Some DH21 plants survived for three years under field conditions (Fig. 3D), and this line was previously used in a molecular genetic study (Liu et al 2021). DH158 depicted ~ 100% survival after two years of cultivation and showed a high growth rate of 2 m in one year of culture (Fig.…”

Variations in Growth and Photosynthetic Traits of Polyploid Poplar Hybrids and Clones in Northeast China

“…The clones were ranked on the basis of growth traits, and the order was similar after being planted from two years to four years, which was distinguished from one-year-old seedlings. This might be determined by the slow seedling phenomenon of one-year-old plants [ 52 ]. The results suggested that there was a certain limitation in the field experiment using one-year-old seedlings as materials compared with seedlings over two years old.…”