Low chromosome number angiosperms

Cremonini, R.

doi:10.1080/00087114.2005.10589480

Cited by 20 publications

(4 citation statements)

References 64 publications

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“…The number of COs during female meiosis is unknown, but this is almost certainly one of the species with the lowest genome-wide recombination level, especially given haplodiploidy and hence absence of recombination in males. A few animal and plant species are known to have just two pairs of chromosomes [55][56][57]. Very variable chromosome size may have similar effects, if a large majority of genes is found on just a single or a few chromosomes.…”

Section: Review: Low Levels Of Recombination In Sexual Speciesmentioning

confidence: 99%

Low recombination rates in sexual species and sex–asex transitions

Haag

Theodosiou

Zahab

et al. 2017

Phil. Trans. R. Soc. B

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In most sexual, diploid eukaryotes, at least one crossover occurs between each pair of homologous chromosomes during meiosis, presumably in order to ensure proper segregation. Well-known exceptions to this rule are species in which one sex does not recombine and specific chromosomes lacking crossover. We review other possible exceptions, including species with chromosome maps of less than 50 cM in one or both sexes. We discuss the idea that low recombination rates may favour sex-asex transitions, or, alternatively may be a consequence of it. We then show that a yet undescribed species of brine shrimp from Kazakhstan ( sp. Kazakhstan), the closest known relative of the asexual , has one of the shortest genetic linkage maps known. Based on a family of 42 individuals and 589 RAD markers, we find that many linkage groups are considerably shorter than 50 cM, suggesting either no obligate crossover or crossovers concentrated at terminal positions with little effect on recombination. We contrast these findings with the published map of the more distantly related sexual congener,, and conclude that the study of recombination in non-model systems is important to understand the evolutionary causes and consequences of recombination.This article is part of the themed issue 'Evolutionary causes and consequences of recombination rate variation in sexual organisms'.

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Section: Review: Low Levels Of Recombination In Sexual Speciesmentioning

confidence: 99%

Low recombination rates in sexual species and sex–asex transitions

Haag

Theodosiou

Zahab

et al. 2017

Phil. Trans. R. Soc. B

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“…One of the extraordinary aspects of plant genomes is how variable they are in terms of chromosome number. Haploid chromosome counts among angiosperms span more than two orders of magnitude, from a low of n = 2 in six different species spread among four angiosperm families (Vanzela et al, 1996; Roberto, 2005), to 320 in the genus Sedum (Crassulaceae) (Uhl, 1978). Driving this diversity are mechanisms that both expand and shrink chromosome numbers, either saltationally via polyploidy, or in a more stepwise fashion via ascending or descending dysploidy.…”

Section: Introductionmentioning

confidence: 99%

The Genome Sequence of Gossypioides kirkii Illustrates a Descending Dysploidy in Plants

et al. 2019

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One of the extraordinary aspects of plant genome evolution is variation in chromosome number, particularly that among closely related species. This is exemplified by the cotton genus (Gossypium) and its relatives, where most species and genera have a base chromosome number of 13. The two exceptions are sister genera that have n = 12 (the Hawaiian Kokia and the East African and Madagascan Gossypioides). We generated a high-quality genome sequence of Gossypioides kirkii (n = 12) using PacBio, Bionano, and Hi-C technologies, and compared this assembly to genome sequences of Kokia (n = 12) and Gossypium diploids (n = 13). Previous analysis demonstrated that the directionality of their reduced chromosome number was through large structural rearrangements. A series of structural rearrangements were identified comparing the de novo G. kirkii genome sequence to genome sequences of Gossypium, including chromosome fusions and inversions. Genome comparison between G. kirkii and Gossypium suggests that multiple steps are required to generate the extant structural differences.

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“…Plants show great diversity in chromosome number. In a well-documented work, lowest chromosome number has been reported as 2n = 4 in Haplopappus gracilis [7] and in several other species [8]. Highest chro-mosome count is known from a fern Ophioglossum reticulatum as n = 720 [9].…”

Section: Introductionmentioning

confidence: 97%