C-banded karyotypes of twoSilenespecies with heteromorphic sex chromosomes

Abstract

Mitotic metaphase chromosomes of Silene latifolia (white campion) and Silene dioica (red campion) were studied and no substantial differences between the conventional karyotypes of these two species were detected. The classification of chromosomes into three distinct groups proposed for S. latifolia by Ciupercescu and colleagues was considered and discussed. Additionally, a new small satellite on the shorter arm of homobrachial chromosome 5 was found. Giemsa C-banded chromosomes of the two analysed species show many fixed and polymorphic heterochromatic bands, mainly distally and centromerically located. Our C-banding studies provided an opportunity to better characterize the sex chromosomes and some autosome types, and to detect differences between the two Silene karyotypes. It was shown that S. latifolia possesses a larger amount of polymorphic heterochromatin, especially of the centromeric type. The two Silene sex chromosomes are easily distinguishable not only by length or DNA amount differences but also by their Giemsa C-banding patterns. All Y chromosomes invariably show only one distally located band, and no other fixed or polymorphic bands on this chromosome were observed in either species. The X chromosomes possess two terminally located fixed bands, and some S. latifolia X chromosomes also have an extra-centric segment of variable length. The heterochromatin amount and distribution revealed by our Giemsa C-banding studies provide a clue to the problem of sex chromosome and karyotype evolution in these two closely related dioecious Silene species.

Recombination changes at the boundaries of fully and partially sex-linked regions between closely related Silene species pairs

“…We consider this less likely, as our analyses of subdivision between males and females suggests partial sex linkage in S. dioica, for at least some of the PAR boundary genes that we tested, implying addition before the split between the species. This is consistent with cytogenetic evidence that both the X and Y chromosomes are very similar in these species (Grabowska-Joachimiak and Joachimiak, 2002), and considerably larger than other chromosomes, unlike the situation in other Silene species (Siroky et al, 2001).…”

“…The S. dioica XY chromosomes are homologous with those of S. latifolia (Nicolas et al, 2005), and have indistinguishable morphology and arm ratios (Grabowska-Joachimiak and Joachimiak, 2002). The two species hybridize readily, producing fertile progeny, consistent with nonrearranged chromosomes, and there is evidence for ongoing gene flow (Muir et al, 2012;Hu and Filatov, 2015).…”

C-Banding/DAPI and in situ Hybridization Reflect Karyotype Structure and Sex Chromosome Differentiation in <i>Humulus japonicus </i>Siebold &#38; Zucc.

“…However, genetic degeneration of male sex chromosomes (i.e., dysfunctionalization or loss of Y-linked genes) remains a controversial topic. Currently there is little evidence for it in flowering plants [Grabowska-Joachimiak and Joachimiak, 2002;Armstrong and Filatov, 2008]. The accumulation of repetitive sequences on the plant Y chromosomes might affect only intergenic sequences and introns [Armstrong and Filatov, 2008;Charlesworth, 2008].…”

A cytogenetic view of sex chromosome evolution in plants

“…Production of mitotic figures has previously relied on germination of seeds and collection of growing root tips. Methods to accumulate metaphase cells have included placing the root tips in ice cold water (Grabowska-Joachimiak and Joachimiak, 2002) or synchronising the cells with aphidicolin and subsequent accumulation of metaphases with oryzalin (Lengerova et al, 2004). We have approached the requirement for large numbers of Silene mitotic metaphases based on the techniques we have developed for cytogenetic analysis of Brassica and Arabidopsis Fransz et al, 1998).…”