Visualization of chromosome condensation in plants with large chromosomes

Abstract

BackgroundMost data concerning chromosome organization have been acquired from studies of a small number of model organisms, the majority of which are mammals. In plants with large genomes, the chromosomes are significantly larger than the animal chromosomes that have been studied to date, and it is possible that chromosome condensation in such plants was modified during evolution. Here, we analyzed chromosome condensation and decondensation processes in order to find structural mechanisms that allowed for an increase in chromosome size.ResultsWe found that anaphase and telophase chromosomes of plants with large chromosomes (average 2C DNA content exceeded 0.8 pg per chromosome) contained chromatin-free cavities in their axial regions in contrast to well-characterized animal chromosomes, which have high chromatin density in the axial regions. Similar to animal chromosomes, two intermediates of chromatin folding were visible inside condensing (during prophase) and decondensing (during telophase) chromosomes of Nigella damascena: approximately 150 nm chromonemata and approximately 300 nm fibers. The spatial folding of the latter fibers occurs in a fundamentally different way than in animal chromosomes, which leads to the formation of chromosomes with axial chromatin-free cavities.ConclusionDifferent compaction topology, but not the number of compaction levels, allowed for the evolution of increased chromosome size in plants.Electronic supplementary materialThe online version of this article (10.1186/s12870-017-1102-7) contains supplementary material, which is available to authorized users.

Variation in the Number and Position of rDNA Loci Contributes to the Diversification and Speciation in Nigella (Ranunculaceae)

“…The diploid species, N. sativa, N. damascena, N. arvensis, N. hispanica and N. orientalis (2 n = 2 x = 12), have five metacentric and one telocentric chromosome pairs, but N. bucharica and N. integrifolia (2 n = 2 x = 14) have four metacentric, two submetacentric and one subtelocentric chromosome pairs ( Gilot-Delhalle et al, 1976 ). The 1C-values of N. sativa and N. damascena were determined to be 10.39 Gbp ( Bennett and Smith, 1976 ) and 10.29 Gbp ( Evans et al, 1972 ; Kuznetsova et al, 2017 ; Leitch et al, 2019 ), respectively. There is little information about the genome composition and cytogenetic characteristics of Nigella species although such information is important to understand the phylogenetic relationship in this genus.…”

Characterization of Lettuce Chromosomes Based on Condensation Patterns and Physical Mapping of 45S and 5S rDNAs Using Fluorescence <i>in situ</i> Hybridization

“…1, 3) and the longest chromosome length (Table 1) in comparison with the other three species. It is suggested that genome sizes of the plants are strongly correlated with chromosome length mainly due to the amount of repetitive DNA sequences in Lilium (Du et al 2017) and Nigella damascena (Kuznetsova et al 2017). Therefore, the present results suggest that the abundance of repetitive DNA in the genomes might have contributed to the genome sizes in Lactuca species, and it is reflected as the CPs of the chromosomes.…”

The Sister Chromatid Division of the Heteromorphic Sex Chromosomes in Silene Species and Their Transmissibility towards the Mitosis

“…This is because the limit of the cell dimension and spindle extension do not favour chromosomes with significantly different lengths, which in turn decreases evolutionary fitness [ 31 ]. Chromosomes of various lengths may also differ in chromosome condensation [ 32 , 33 ], affecting chromosome stiffness and sister chromatid division during mitosis [ 34 ]. The decrease in chromosome velocity (movement) was shown to be reduced by specific chromosome positioning so far in Melanoplus [ 35 ].…”