Cytological Analyses in Melandrium album: Genome Size, C.hromosome Size and Fluorescence in situ Hybridization.

Matsunaga, Sachihiro; Hizume, Masahiro; Kawano, Shigeyuki; Kuroiwa, Tsuneyoshi

doi:10.1508/cytologia.59.135

Cited by 38 publications

(29 citation statements)

References 33 publications

(19 reference statements)

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“…To estimate the physical size (in megabases) of a centimorgan in S. latifolia, we used the estimated genome size of 2879 Mb (Vagera et al 1994) and assumed that 14% of the female genome is represented by the X chromosome of 350 Mb and that 86% is autosomal, representing 2076 Mb (Matsunaga et al 1994).…”

Section: Linkage Analysismentioning

confidence: 99%

Expansion of the Pseudo-autosomal Region and Ongoing Recombination Suppression in the Silene latifolia Sex Chromosomes

Bergero

Qiu

Forrest³

et al. 2013

Genetics

122

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There are two very interesting aspects to the evolution of sex chromosomes: what happens after recombination between these chromosome pairs stops and why suppressed recombination evolves. The former question has been intensively studied in a diversity of organisms, but the latter has been studied largely theoretically. To obtain empirical data, we used codominant genic markers in genetic mapping of the dioecious plant Silene latifolia, together with comparative mapping of S. latifolia sex-linked genes in S. vulgaris (a related hermaphrodite species without sex chromosomes). We mapped 29 S. latifolia fully sex-linked genes (including 21 newly discovered from transcriptome sequencing), plus 6 genes in a recombining pseudo-autosomal region (PAR) whose genetic map length is 25 cM in both male and female meiosis, suggesting that the PAR may contain many genes. Our comparative mapping shows that most fully sex-linked genes in S. latifolia are located on a single S. vulgaris linkage group and were probably inherited from a single autosome of an ancestor. However, unexpectedly, our maps suggest that the S. latifolia PAR region expanded through translocation events. Some genes in these regions still recombine in S. latifolia, but some genes from both addition events are now fully sex-linked. Recombination suppression is therefore still ongoing in S. latifolia, and multiple recombination suppression events have occurred in a timescale of few million years, much shorter than the timescale of formation of the most recent evolutionary strata of mammal and bird sex chromosomes. It is now understood that the large nonrecombining regions of sex chromosomes in mammals have expanded over evolutionary time, forming "evolutionary strata" with differing levels of sequence divergence between X-and Y-gene pairs, from ancient highly diverged regions, to regions in which the genes started diverging much more recently, which are located closest to the pseudo-autosomal region (PAR) on the X chromosome genetic and physical maps (Lahn and Page 1999;Skaletsky et al. 2003;Marais et al. 2008). The more recent evolutionary strata were formed by recombination suppression in regions formed by an addition of autosomal genetic material to the sex chromosomes (Waters et al. 2001), demonstrating that suppressed recombination spread from the ancestral sex chromosomal region into initially recombining regions. The PAR is shared across Eutherian mammals (despite differences in its boundary and the recent addition of a second PAR, PAR2, in humans), which is a physically small remnant of the added region, which is still autosomal in marsupials (Waters et al. 2001).The major current explanation for the evolution of expanded nonrecombining regions of sex chromosomes is

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Section: Linkage Analysismentioning

confidence: 99%

Expansion of the Pseudo-autosomal Region and Ongoing Recombination Suppression in the Silene latifolia Sex Chromosomes

Bergero

Qiu

Forrest³

et al. 2013

Genetics

122

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“…Sequence comparison of X and Y BACs in the MSY region has shown that the papaya MSY has been expanded by the accumulation of repetitive DNA . Moreover, most of the plant Ys, including those of S. latifolia (Matsunaga et al, 1994), R. acetosa (Parker, 1990) and Cannabis sativa (Sakamoto et al, 1998) are the largest in the male genome. The Y 1 and Y 2 chromosomes of R. acetosa account for about 26% of the male genome (Wilby and Parker, 1987), while those of S. latifolia represent around 9% (Matsunaga et al, 1994).…”

Section: Repetitive Dna Contributes To Y Chromosome Extension and Degmentioning

confidence: 99%

Plant sex chromosomes: molecular structure and function

Jamilena

Mariotti

Manzano³

2008

Cytogenet Genome Res

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Recent molecular and genomic studies carried out in a number of model dioecious plant species, including Asparagus officinalis, Carica papaya, Silene latifolia, Rumex acetosa and Marchantia polymorpha, have shed light on the molecular structure of both homomorphic and heteromorphic sex chromosomes, and also on the gene functions they have maintained since their evolution from a pair of autosomes. The molecular structure of sex chromosomes in species from different plant families represents the evolutionary pathway followed by sex chromosomes during their evolution. The degree of Y chromosome degeneration that accompanies the suppression of recombination between the Xs and Ys differs among species. The primitive Ys of A. officinalis and C. papaya have only diverged from their homomorphic Xs in a short male-specific and non-recombining region (MSY), while the heteromorphic Ys of S. latifolia, R. acetosa and M. polymorpha have diverged from their respective Xs. As in the Y chromosomes of mammals and Drosophila, the accumulation of repetitive DNA, including both transposable elements and satellite DNA, has played an important role in the divergence and size enlargement of plant Ys, and consequently in reducing gene density. Nevertheless, the degeneration process in plants does not appear to have reached the Y-linked genes. Although a low gene density has been found in the sequenced Y chromosome of M. polymorpha, most of its genes are essential and are expressed in the vegetative and reproductive organs in both male and females. Similarly, most of the Y-linked genes that have been isolated and characterized up to now in S. latifolia are housekeeping genes that have X-linked homologues, and are therefore expressed in both males and females. Only one of them seems to be degenerate with respect to its homologous region in the X. Sequence analysis of larger regions in the homomorphic X and Y chromosomes of papaya and asparagus, and also in the heteromorphic sex chromosomes of S. latifolia and R. acetosa, will reveal the degenerative changes that the Y-linked gene functions have experienced during sex chromosome evolution.

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“…In contrast, almost all heteromorphic Y chromosomes in angiosperms are the largest chromosomes in the male genomes. For example, the Y and X chromosomes are the largest and second-largest chromosomes of male S. latifolia, with the Y chromosome containing approximately 9% of its total diploid genome (Matsunaga et al, 1994). The Y chromosomes of Cannabis sativa are also the largest in the male genome (Sakamoto et al, 1998), and although the R. acetosa Y chromosome is divided into Y 1 and Y 2 , the overall combined Y chromosome is the largest in the male genome (Shibata et al, 1999).…”

Section: A Mads Box Gene Linked To the Y Chromosomementioning

confidence: 99%

“…By studying mutants with various Y chromosome deletions, it was revealed that the Y chromosome of S. latifolia has at least three different loci that are involved in suppression of female development, and in initiation and completion of anther development Moore et al, 2003). The Y chromosome of S. latifolia is the largest chromosome in the male genome and is not heterochromatic in character, unlike the human Y chromosome (Matsunaga et al, 1994, 1999a. Although over 80 years have passed since the discovery of plant sex chromosomes in flowering plants, there are extremely limited reports of plant sex chromosome-linked genes.…”

Section: Introductionmentioning

confidence: 99%

Sex chromosome-linked genes in plants

Matsunaga

2006

Genes Genet. Syst.

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Recent studies of plant sex chromosome-linked genes have revealed many interesting characteristics, although there are limited reports about heteromorphic sex chromosomes in flowering plants. Sex chromosome-linked genes in angiosperms have been characterized mainly in the dioecious plant Silene latifolia . Although all such genes were isolated from transcripts of male flower buds of S. latifolia , most seem to be housekeeping genes except for the petal-and stamen-specific MADS box gene on the Y chromosome ( SlAP3Y ) and the male reproductive organspecific gene on the X chromosome ( MROS3X ). Recent evolutionary studies have revealed at least three evolutionary strata on the X chromosome that are related to stepwise loss of recombination between the sex chromosomes. Moreover, genetic maps showed conservation of gene organization on the X chromosome in the genus Silene and substantial pericentric inversion between the X and Y chromosomes of S. latifolia during evolution. A comparison between paralogs on the sex chromosomes revealed that introns of the Y-linked genes are longer than those of X-linked paralogs. Although analyses of sex chromosome-linked genes suggest that degeneration of the Y chromosome has occurred, the Y chromosome in flowering plants remains the largest in the male genome, unlike that of mammals. Accumulation of repetitive sequences and the entire chloroplast genome on the Y chromosome appear to have contributed to this large size. However, more detailed studies will be required to help explain the basis for the fact that heteromorphic sex chromosomes in angiosperms are large.

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Cytological Analyses in Melandrium album: Genome Size, C.hromosome Size and Fluorescence in situ Hybridization.

Cited by 38 publications

References 33 publications

Expansion of the Pseudo-autosomal Region and Ongoing Recombination Suppression in the Silene latifolia Sex Chromosomes

Expansion of the Pseudo-autosomal Region and Ongoing Recombination Suppression in the Silene latifolia Sex Chromosomes

Plant sex chromosomes: molecular structure and function

Sex chromosome-linked genes in plants

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