Is the aneuploid chromosome in an apomictic &lt;i&gt;Boechera holboellii&lt;/i&gt; a genuine B chromosome?

Sharbel, Timothy F.; Voigt, Marie-Luise; Mitchell-Olds, Thomas; Kantama, Laksana; Jong, J.H.S.G.M. de

doi:10.1159/000079284

Cited by 46 publications

(52 citation statements)

References 33 publications

(61 reference statements)

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“…com.). Aneuploidy was reported in the B. holboellii species complex (Bo¨cher 1951, Roy 1995, Sharbel and Mitchell-Olds 2001, and recent studies involving DNA sequences of microsatellites markers (Sharbel et al 2004) suggest that aneuploidy involves non-recombining B chromosomes that may also play a role in apomixis.…”

Section: Problematic Groupsmentioning

confidence: 99%

“…, 2004aDobesě t al. , 2004bKoch et al 2003c;Sharbel et al 2004) Windham et al (2004), the first serious problem in the study of Boechera is taxon identity, and erroneous determinations in the holdings of the major herbaria can be as high as 40%. Hybridization appears to have played a far more major role in the evolution of the genus than was suggested by Rollins (1983) and Mulligan (1996).…”

Section: Problematic Groupsmentioning

confidence: 99%

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Systematics and phylogeny of the Brassicaceae (Cruciferae): an overview

2006

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Abstract. A critical review of characters used in the systematics of the Brassicaceae is given, and aspects of the origin, classification, and generic delimitation of the family discussed. Molecular phylogenetic studies of the family were reviewed, and major clades identified. Based on molecular studies, especially from the ndhF chloroplast gene, and careful evaluation of morphology and generic circumscriptions, a new tribal alignment of the Brassicaceae is proposed. In all, 25 tribes are recognized, of which seven (Aethionemeae, Boechereae, Descurainieae, Eutremeae, Halimolobeae, Noccaeeae, and Smelowskieae) are described as new. For each tribe, the center(s) of distribution, morphology, and number of taxa are given. Of the 338 genera currently recognized in the Brassicaceae, about 260 genera (or about 77%) were either assigned or tentatively assigned to the 25 tribes. Some problems relating to various genera and tribes are discussed, and future research developments are briefly covered.

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Section: Problematic Groupsmentioning

confidence: 99%

Section: Problematic Groupsmentioning

confidence: 99%

Systematics and phylogeny of the Brassicaceae (Cruciferae): an overview

2006

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“…Heterochromatic chromosomes (Het) and supernumary heterochromatic-B chromosomes have been detected in asexually reproducing (apomictic) Boechera lines (Sharbel et al, 2004;Kantama, 2005;Sharbel et al, 2005). The Het chromosome is derived from B. stricta as based on hybridization of pericentromeric repeats (Kantama, 2005;Schranz et al, 2006a) and genetic analysis has demonstrated that the Het chromosome can be crossed into B. stricta without conferring a dominant apomictic phenotype (Schranz et al, 2006a).…”

Section: Recombination Suppression Of Bstlg1mentioning

confidence: 99%

“…Numerous studies have analyzed molecular and phenotypic diversity of Boechera species. This includes the molecular evolutionary analysis of gene families (Bishop et al, 2000;Schein et al, 2004;Benderoth et al, 2006), the phylogeography of haplotypes (Dobeš et al, 2004b;Song et al, 2006), the occurrence of supernumary B chromosomes (Böcher, 1951;Sharbel et al, 2004), variation in breeding systems and ploidy (Sharbel and MitchellOlds, 2001;Schranz et al, 2005;Schranz et al, 2006a), drought tolerance (Knight et al, 2006), morphological and taxonomical diversity (Rollins, 1993;Al-Shehbaz, 2003;Windham and Al-Shehbaz, 2006), and the evolved responses to pathogen or insect pests (Roy, 1993;Roy and Kirchner, 2000;Jones et al, 2006). The further elucidation of these and other patterns of variation would be greatly aided by the creation and analysis of segregating genetic stocks.…”

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confidence: 99%

Comparative Genetic Mapping inBoechera stricta, a Close Relative of Arabidopsis

et al. 2007

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The angiosperm family Brassicaceae contains both the research model Arabidopsis (Arabidopsis thaliana) and the agricultural genus Brassica. Comparative genomics in the Brassicaceae has largely focused on direct comparisons between Arabidopsis and the species of interest. However, the reduced genome size and chromosome number (n 5 5) of Arabidopsis complicates comparisons. Arabidopsis shows extensive genome and chromosome reshuffling compared to its close relatives Arabidopsis lyrata and Capsella rubella, both with n 5 8. To facilitate comparative genomics across the Brassicaceae we recently outlined a system of 24 conserved chromosomal blocks based on their positions in an ancestral karyotype of n 5 8, rather than by their position in Arabidopsis. In this report we use this system as a tool to understand genome structure and evolution in Boechera stricta (n 5 7). B. stricta is a diploid, sexual, and highly self-fertilizing species occurring in mostly montane regions of western North America. We have created an F 2 genetic map of B. stricta based on 192 individuals scored at 196 microsatellite and candidate gene loci. Single-nucleotide polymorphism genotyping of 94 of the loci was done simultaneously using an Illumina bead array. The total map length is 725.8 cM, with an average marker spacing of 3.9 cM. There are no gaps greater than 19.3 cM. The chromosomal reduction from n 5 8 to n 5 7 and other genomic changes in B. stricta likely involved a pericentric inversion, a chromosomal fusion, and two reciprocal translocations that are easily visualized using the genomic blocks. Our genetic map will facilitate the analysis of ecologically relevant quantitative variation in Boechera.Comparative genetic mapping between related organisms within a phylogenetic framework is a powerful method for understanding genome evolution. Comparative mapping in the grass family (Poaceae) has been successful in detecting collinear genomic regions between a number of domesticated cereal and forage crops, leading to the formulation of the crop circle with rice (Oryza sativa) at the center (Moore et al., 1995;Devos, 2005). Rice was selected as the reference point because of its small genome and vast genomic resources, and not because it was phylogenetically well positioned to facilitate comparisons within the family. An analogous situation occurs in the dicot family Brassicaceae, which contains both the model species Arabidopsis (Arabidopsis thaliana) as well as the domesticated Brassica species. To date, most comparative genomics in the Brassicaceae has largely focused on direct comparisons between Arabidopsis and the species of interest. However, several of the factors that made Arabidopsis ideal for genome sequencing, particularly its reduced genome size and chromosome number (157 Mb, n 5 5; AGI, 2000;Johnston et al., 2005), complicate its use as a standard in comparative genomics. Recent phylogenetic results have demonstrated that genome and chromosome reduction in Arabidopsis are derived characteristics from its close relatives with...

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“…The extra chromosomes recorded in our study may be B chromosomes as they varied in number (0-1) between and within populations, which is a characteristic of this type of chromosome. B chromosomes are not essential for the organism, are often heterochromatic and rich in repetitive sequences (Sharbel et al 2004), features, however, which we have not yet established. In the numerous chromosome counts for V. officinalis aneuploidy is never mentioned (Titz 1964, 1969, Titz & Titz 1979, 1981, and one could suppose that the occurrence of aneuploidy is relatively rare.…”

Section: Frequencies Of Cytotypes Of Deviant Ploidy and Of Aneuploidsmentioning

confidence: 81%

Variation in genome size in the Valeriana officinalis complex resulting from multiple chromosomal evolutionary processes

Bressler¹,

Klatte-Asselmeyer²,

Fischer³

et al. 2017

Preslia

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Polyploidy, aneuploidy and change in DNA content of monoploid genomes or chromosomes are the principal causes of the variation in genome size. We studied these phenomena in central-European populations of the Valeriana officinalis complex in order to identify mechanisms or forces driving its evolution. The complex comprises di-, tetra-and octoploid morphologically defined so-called taxonomic "types". Within the study area there are also intermediate "transitional types" the existence of which hampers the application of traditional taxonomic concepts. We thus chose AFLP genotyping and admixture analyses to identify the genetic structuring of the material studied. Di-(2x), tetra-(4x) and octoploidy (8x) were confirmed as major ploidy levels. Major genetic clusters roughly corresponded to these ploidy levels (for K = 2: 2x-and 8x-clusters, for K = 4 with nearly identical probability: 2x-, 4x-, 8x-and unspecific clusters were identified), which further more significantly differed from each other in monoploid absolute genome size (mean 1Cx for 2x = 1.48 pg, 4x 1.29 pg, 8x 1.10 pg). Several individuals of all ploidy levels were admixed, particularly tetraploids. Relative genome size (the sample: standard DAPI fluorescence) was positively correlated with the proportion of the diploid genetic cluster shared by the tetraploids, indicating that hybridization caused the variation in genome size. This result is in accordance with the significant negative correlation of the genome size of tetraploids with their geographic distance to the diploids. However, remarkable intra-ploidy variation in relative genome size was recorded for all ploidy levels (1.14-fold in diploids, 1.28-fold in tetraploids, 1.19-fold in octoploids). We identified aneuploidy as an additional source of variation in genome size in the di-and tetraploids. The contribution of extra chromosomes to absolute genome size exceeded the observed variation within euploids in the diploids, whereas it was included in the regular variability in genome size recorded for the eutetraploids. Variation in monoploid genome size was recorded in polyploids but not in diploids, indicating that polyploids experienced higher dynamics in the evolution of their genomes. Finally, 38.0-63.2% of the total intra-ploidy variation in relative genome size occurred within populations. In conclusion, the Valeriana officinalis complex provides an example of variation in genome size due to four principal evolutionary forces: polyploidization, change in chromosome number and in DNA content of chromosomes and (secondarily) hybridization, but their relative importance differed among ploidy levels. Although the stability in the size of the monoploid genome in species is considered to be the standard case, we found great variability within populations suggesting that genome size is variable even within narrowly defined taxa.

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Is the aneuploid chromosome in an apomictic <i>Boechera holboellii</i> a genuine B chromosome?

Cited by 46 publications

References 33 publications

Systematics and phylogeny of the Brassicaceae (Cruciferae): an overview

Systematics and phylogeny of the Brassicaceae (Cruciferae): an overview

Comparative Genetic Mapping inBoechera stricta, a Close Relative of Arabidopsis

Variation in genome size in the Valeriana officinalis complex resulting from multiple chromosomal evolutionary processes

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