Homoeologous Chromosomes From Two Hordeum Species Can Recognize and Associate During Meiosis in Wheat in the Presence of the Ph1 Locus

Bread wheat is an allohexaploid that behaves as a diploid during meiosis, the cell division process to produce the gametes occurring in organisms with sexual reproduction. Knowledge of the mechanisms implicated in meiosis can contribute to facilitating the transfer of desirable traits from related species into a crop like wheat in the framework of breeding. It is particularly interesting to shed light on the mechanisms controlling correct pairing between homologous (equivalent) chromosomes and recombination, even more in polyploid species. The Ph1 (Pairing homoeologous 1) locus is implicated in recombination. In this work, we aimed to study whether homoeologous (equivalent chromosomes from different genomes) Hordeum chilense (wild barley) and H. vulgare (cultivated barley) chromosomes can associate and recombine during meiosis in the wheat background in the absence of the Ph1 locus. For this, we have developed H. chilense and H. vulgare double monosomic addition lines for the same and for different homoeology group in wheat in the ph1b mutant background. Using genomic in situ hybridization, we visualized the two (wild and cultivated) barley chromosomes during meiosis and we studied the processes of recognition, association, and recombination between homoeologous chromosomes in the absence of the Ph1 locus. Our results showed that the Ph1 locus does not prevent homoeologous chromosome pairing but it can regulate recombination.

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Centromere association is an unlikely mechanism by which the wheat Ph1 locus regulates metaphase I chromosome pairing between homoeologous chromosomes

Chromosoma ◽

10.1007/s004120000093 ◽

2000 ◽

Vol 109 (6) ◽

pp. 410-414 ◽

Cited By ~ 16

Author(s):

Jan Dvorak ◽

Adam J. Lukaszewski

Keyword(s):

Chromosome Pairing ◽

Ph1 Locus ◽

Homoeologous Chromosomes ◽

Metaphase I

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Genetic control of meiotic chromosome pairing in polyploids in the genus Hordeum

Canadian Journal of Genetics and Cytology ◽

10.1139/g85-077 ◽

1985 ◽

Vol 27 (5) ◽

pp. 515-530 ◽

Cited By ~ 40

Author(s):

P. K. Gupta ◽

George Fedak

Keyword(s):

Chromosome Pairing ◽

Interspecific Hybrids ◽

Meiotic Chromosome ◽

Intergeneric Hybrid ◽

Meiotic Pairing ◽

Major Locus ◽

In The Wild ◽

Hordeum Species ◽

Homoeologous Chromosomes ◽

Existing Data

Existing data on meiosis in hexaploid and tetraploid species of Hordeum, their respective polyhaploids, and intergeneric – interspecific hybrids indicate that a meiotic pairing control system exists in this genus. The system is probably polygenic and it is therefore unlikely that a major locus such as Ph in Triticum controls chromosome pairing. It is more efficient in the tetraploids than hexaploids, permitting some intergenomic pairing in the latter. In the polyhaploids the pairing control is somewhat hemizygous ineffective. The pairing of homoeologous chromosomes in the wild polyploid Hordeum species is generally inhibited by H. vulgare and variably enhanced by genomes of Secale species.Key words: Hordeum, synapsis regulation, intergeneric hybrid, polyhaploids, hemizygous.

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Allelism for Awn Length, lk2, in Barley ( Hordeum species) 1

Crop Science ◽

10.2135/cropsci1967.0011183x000700030030x ◽

1967 ◽

Vol 7 (3) ◽

pp. 266-267 ◽

Cited By ~ 2

Author(s):

R. F. Eslick ◽

E. A. Hockett

Keyword(s):

Hordeum Species

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PrBn, a Major Gene Controlling Homeologous Pairing in Oilseed Rape (Brassica napus) Haploids

Genetics ◽

10.1093/genetics/164.2.645 ◽

2003 ◽

Vol 164 (2) ◽

pp. 645-653 ◽

Cited By ~ 4

Author(s):

Eric Jenczewski ◽

Frédérique Eber ◽

Agnès Grimaud ◽

Sylvie Huet ◽

Marie Odile Lucas ◽

...

Keyword(s):

Brassica Napus ◽

Oilseed Rape ◽

Chromosome Pairing ◽

Major Gene ◽

Major Effect ◽

F1 Hybrids ◽

Precise Control ◽

Ph1 Locus ◽

Likelihood Approach ◽

Likelihood Ratio Statistics

Abstract Precise control of chromosome pairing is vital for conferring meiotic, and hence reproductive, stability in sexually reproducing polyploids. Apart from the Ph1 locus of wheat that suppresses homeologous pairing, little is known about the activity of genes that contribute to the cytological diploidization of allopolyploids. In oilseed rape (Brassica napus) haploids, the amount of chromosome pairing at metaphase I (MI) of meiosis varies depending on the varieties the haploids originate from. In this study, we combined a segregation analysis with a maximum-likelihood approach to demonstrate that this variation is genetically based and controlled mainly by a gene with a major effect. A total of 244 haploids were produced from F1 hybrids between a high- and a low-pairing variety (at the haploid stage) and their meiotic behavior at MI was characterized. Likelihood-ratio statistics were used to demonstrate that the distribution of the number of univalents among these haploids was consistent with the segregation of a diallelic major gene, presumably in a background of polygenic variation. Our observations suggest that this gene, named PrBn, is different from Ph1 and could thus provide complementary information on the meiotic stabilization of chromosome pairing in allopolyploid species.

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Reaction of Hordeum species to the smut fungi Ustilago nuda and U. tritici

Canadian Journal of Botany ◽

10.1139/b87-276 ◽

1987 ◽

Vol 65 (10) ◽

pp. 2024-2027 ◽

Cited By ~ 4

Author(s):

J. Nielsen

Keyword(s):

Hordeum Chilense ◽

Smut Fungi ◽

New Hosts ◽

Cultivated Barley ◽

Ustilago Nuda ◽

Hordeum Species ◽

Eleven Species

Eleven species of Hordeum were tested for their reaction to Ustilago nuda (Jens.) Rostr. and U. tritici (Pers.) Rostr., the causes of the embryo-infecting loose smuts of cultivated barley and wheat, respectively. The species Hordeum chilense and H. depressum were resistant, while H. euclaston, H. halophilum, H. procerum, H. pusillum, and H. stenostachys were susceptible to both fungi. Hordeum muticum was susceptible only to U. nuda, while H. arizonicum, H. lechleri, and H. roshevitzii were susceptible only to U. tritici. The susceptible species are new hosts for these pathogens. It is proposed that these results, together with those of an earlier study, indicate that U. nuda evolved from U. tritici.

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Characterization of Each St and Y Genome Chromosome of Roegneria grandis Based on Newly Developed FISH Markers

Cytogenetic and Genome Research ◽

10.1159/000515623 ◽

2021 ◽

pp. 213-222

Author(s):

Dandan Wu ◽

Xiaoxia Zhu ◽

Lu Tan ◽

Haiqin Zhang ◽

Lina Sha ◽

...

Keyword(s):

Structural Changes ◽

Distribution Patterns ◽

Proximal Region ◽

Genome Chromosome ◽

High Affinity ◽

Complete Set ◽

Genome Analyses ◽

First Time ◽

Homoeologous Chromosomes

The genera of the tribe Triticeae (family Poaceae), constituting many economically important plants with abundant genetic resources, carry genomes such as St, H, P, and Y. The genome symbol of Roegneria C. Koch (Triticeae) is StY. The St and Y genomes are crucial in Triticeae, and tetraploid StY species participate extensively in polyploid speciation. Characterization of St and Y nonhomologous chromosomes in StY-genome species could help understand variation in the chromosome structure and differentiation of StY-containing species. However, the high genetic affinity between St and Y genome and the deficiency of a complete set of StY nonhomologous probes limit the identification of St and Y genomes and variation of chromosome structures among Roegneria species. We aimed to identify St- and Y-enhanced repeat clusters and to study whether homoeologous chromosomes between St and Y genomes could be accurately identified due to high affinity. We employed comparative genome analyses to identify St- and Y-enhanced repeat clusters and generated a FISH-based karyotype of R. grandis (Keng), one of the taxonomically controversial StY species, for the first time. We explored 4 novel repeat clusters (StY_34, StY_107, StY_90, and StY_93), which could specifically identify individual St and Y nonhomologous chromosomes. The clusters StY_107 and StY_90 could identify St and Y addition/substitution chromosomes against common wheat genetic backgrounds. The chromosomes V_St, VII_St, I_Y, V_Y, and VII_Y displayed similar probe distribution patterns in the proximal region, indicating that the high affinity between St and Y genome might result from chromosome rearrangements or transposable element insertion among V_St/Y, VII_St/Y, and I_Y chromosomes during allopolyploidization. Our results can be used to employ FISH further to uncover the precise karyotype based on colinearity of Triticeae species by using the wheat karyotype as reference, to analyze diverse populations of the same species to understand the intraspecific structural changes, and to generate the karyotype of different StY-containing species to understand the interspecific chromosome variation.

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NONSTRUCTURAL CHROMOSOME DIFFERENTIATION AMONG WHEAT CULTIVARS, WITH SPECIAL REFERENCE TO DIFFERENTIATION OF CHROMOSOMES IN RELATED SPECIES

Genetics ◽

10.1093/genetics/97.2.391 ◽

1981 ◽

Vol 97 (2) ◽

pp. 391-414

Author(s):

Jan Dvořák ◽

Patrick E McGuire

Keyword(s):

Chinese Spring ◽

Structural Changes ◽

Wheat Cultivar ◽

Chromosome Complement ◽

Triticum Aestivum L ◽

Substitution Lines ◽

Structural Differentiation ◽

Chromosome Differentiation ◽

Mother Cells ◽

Homoeologous Chromosomes

ABSTRACT Wheat cultivar Chinese Spring (Triticum aestivum L. em. Thell.) was crossed with cultivars Hope, Cheyenne and Timstein. In all three hybrids, the frequencies of pollen mother cells (PMCs) with univalents at metaphase I (MI) were higher than those in the parental cultivars. No multivalents were observed in the hybrids, indicating that the cultivars do not differ by translocations. Thirty-one Chinese Spring telosomic lines were then crossed with substitution lines in which single chromosomes of the three cultivars were substituted for their Chinese Spring homologues. The telosomic lines were also crossed with Chinese Spring. Data were collected on the frequencies (% of PMCs) of pairing of the telesomes with their homologues at MI and the regularity of pairing of the remaining 20 pairs of Chinese Spring chromosomes in the monotelodisomics obtained from these crosses. The reduced MI pairing in the intercultivar hybrids was caused primarily by chromosome differentiation, rather than by specific genes. Because the differentiation involved a large part of the chromosome complement in each hybrid, it was concluded that it could not be caused by structural changes such as inversions or translocations. In each case, the differentiation appeared to be unevenly distributed among the three wheat genomes. It is proposed that the same kind of differentiation, although of greater magnitude, differentiates homoeologous chromosomes and is responsible, together with structural differentiation, for poor chromosome pairing in interspecific hybrids.

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Molecular phylogeny of diploid Hordeum species and incongruence between chloroplast and nuclear datasets

Genome ◽

10.1139/g11-063 ◽

2011 ◽

Vol 54 (12) ◽

pp. 986-992 ◽

Cited By ~ 7

Author(s):

Huan Wang ◽

Dongfa Sun ◽

Genlou Sun

Keyword(s):

Evolutionary History ◽

Nuclear Gene ◽

Intergenic Spacer ◽

Molecular Data ◽

Genome Species ◽

Different Types ◽

History Of ◽

Morphological And Molecular Data ◽

Hordeum Species ◽

Eurasian Species

The phylogeny of diploid Hordeum species has been studied using both chloroplast and nuclear gene sequences. However, the studies of different nuclear datasets of Hordeum species often arrived at similar conclusions, whereas the studies of different chloroplast DNA data generally resulted in inconsistent conclusions. Although the monophyly of the genus is well supported by both morphological and molecular data, the intrageneric phylogeny is still a matter of controversy. To better understand the evolutionary history of Hordeum species, two chloroplast gene loci (trnD-trnT intergenic spacer and rps16 gene) and one nuclear marker (thioreoxin-like gene (HTL)) were used to explore the phylogeny of Hordeum species. Two obviously different types of trnD-trnT sequences were observed, with an approximately 210 base pair difference between these two types: one for American species, another for Eurasian species. The trnD-trnT data generally separated the diploid Hordeum species into Eurasian and American clades, with the exception of Hordeum marinum subsp. gussoneanum. The rps16 data also grouped most American species together and suggested that Hordeum flexuosum has a different plastid type from the remaining American species. The nuclear gene HTL data clearly divided Hordeum species into two clades: the Xu + H genome clade and the Xa + I genome clade. Within clades, H genome species were well separated from the Xu species, and the I genome species were well separated from the Xa genome species. The incongruence between chloroplast and nuclear datasets was found and discussed.

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