Meiotic homoeologous recombination-based mapping of wheat chromosome 2B and its homoeologues in Aegilops speltoides and Thinopyrum elongatum

Restriction fragment length polymorphism (RFLP) analysis and multicolor genomic in situ hybridization (GISH) are useful tools to precisely characterize genetic stocks derived from crosses of wheat (Triticum aestivum) with Thinopyrum intermedium and Thinopyrum elongatum. The wheat × Th. intermedium derived stocks designated Z1, Z2, Z3, Z4, Z5, and Z6 were initially screened by multicolor GISH using Aegilops speltoides genomic DNA for blocking and various combinations of genomic DNA from Th. intermedium, Triticum urartu, and Aegilops tauschii for probes. The probing (GISH) results indicated that lines Z1 and Z3 were alien disomic addition lines with chromosome numbers of 2n = 44. Z2 was a substitution line in which chromosome 2D was substituted by a pair of Th. intermedium chromosomes; this was confirmed by RFLP and muticolour GISH. Z4 (2n = 44) contained two pairs of wheat Th. intermedium translocated chromosomes; one pair involved A-genome chromosomes, the other involved D- and A-genome chromosomes. Z5 (2n = 44) contained one pair of wheat Th. intermedium translocated chromosomes involving the D- and A-genome chromosomes of wheat. Z6 (2n = 44) contained one pair of chromosomes derived from Th. intermedium plus another pair of translocated chromosomes involving B-genome chromosomes of wheat. Line Z2 was of special interest because it has some resistance to infection by Fusarium graminearum.Key words: wheat, Thinopyrum intermedium, addition, substitution, and translocation lines, GISH, multicolor GISH, RFLP.

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Genome-wide homology analysis reveals new insights into the origin of the wheat B genome

10.1101/197640 ◽

2017 ◽

Author(s):

Wei Zhang ◽

Mingyi Zhang ◽

Xianwen Zhu ◽

Yaping Cao ◽

Qing Sun ◽

...

Keyword(s):

Wheat Chromosome ◽

Genomic Region ◽

Aegilops Speltoides ◽

Origin And Evolution ◽

Homology Analysis ◽

B Genome ◽

Genome Wide ◽

Polyploid Genome ◽

Relationship Of ◽

The Relationship

AbstractWheat is a typical allopolyploid with three homoeologous subgenomes (A, B, and D). The ancestors of the subgenomes A and D had been identified, but not for the subgenome B. The goatgrass Aegilops speltoides (genome SS) has been controversially considered a candidate for the ancestor of the wheat B genome. However, the relationship of the Ae. speltoides S genome with the wheat B genome remains largely obscure, which has puzzled the wheat research community for nearly a century. In the present study, the genome-wide homology analysis identified perceptible homology between wheat chromosome 1B and Ae. speltoides chromosome 1S, but not between other chromosomes in the B and S genomes. An Ae. speltoides-originated segment spanning a genomic region of approximately 10.46 Mb was identified on the long arm of wheat chromosome 1B (1BL). The Ae. speltoides-originated segment on 1BL was found to co-evolve with the rest of the B genome in wheat species. Thereby, we conclude that Ae. speltoides had been involved in the origin of the wheat B genome, but should not be considered an exclusive ancestor of this genome. The wheat B genome might have a polyphyletic origin with multiple ancestors involved, including Ae. speltoides. These novel findings provide significant insights into the origin and evolution of the wheat B genome, and will facilitate polyploid genome studies in wheat and other plants as well.

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Genetic and physical mapping of homoeologous recombination points involving wheat chromosome 2B and rye chromosome 2R

Genome ◽

10.1139/g03-089 ◽

2004 ◽

Vol 47 (1) ◽

pp. 36-45 ◽

Cited By ~ 59

Author(s):

A J Lukaszewski ◽

K Rybka ◽

V Korzun ◽

S V Malyshev ◽

B Lapinski ◽

...

Keyword(s):

Homologous Recombination ◽

Genetic Map ◽

Physical Mapping ◽

Dna Sequences ◽

Wheat Chromosome ◽

Genetic Maps ◽

Homoeologous Recombination ◽

Chromosome Engineering ◽

Genetic And Physical Mapping ◽

Structural Differences

Wide hybrids have been used in generating genetic maps of many plant species. In this study, genetic and physical mapping was performed on ph1b-induced recombinants of rye chromosome 2R in wheat (Triticum aestivum L.). All recombinants were single breakpoint translocations. Recombination 2RS–2BS was absent from the terminal and the pericentric regions and was distributed randomly along an intercalary segment covering approximately 65% of the arm's length. Such a distribution probably resulted from structural differences at the telomeres of 2RS and wheat 2BS arm that disrupted telomeric initiation of pairing. Recombination 2RL–2BL was confined to the terminal 25% of the arm's length. A genetic map of homoeologous recombination 2R–2B was generated using relative recombination frequencies and aligned with maps of chromosomes 2B and 2R based on homologous recombination. The alignment of the short arms showed a shift of homoeologous recombination toward the centromere. On the long arms, the distribution of homoeologous recombination was the same as that of homologous recombination in the distal halves of the maps, but the absence of multiple crossovers in homoeologous recombination eliminated the proximal half of the map. The results confirm that homoeologous recombination in wheat is based on single exchanges per arm, indicate that the distribution of these single homoeologous exchanges is similar to the distribution of the first (distal) crossovers in homologues, and suggest that successive crossovers in an arm generate specific portions of genetic maps. A difference in the distribution of recombination between the short and long arms indicates that the distal crossover localization in wheat is not dictated by a restricted distribution of DNA sequences capable of recombination but by the pattern of pairing initiation, and that can be affected by structural differences. Restriction of homoeologous recombination to single crossovers in the distal part of the genetic map complicates chromosome engineering efforts targeting genes in the proximal map regions.Key words: homoeologous recombination, genetic mapping, RFLP, RAPD, wheat, rye.

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Molecular cytogenetic identification of nullisomy 5B induced homoeologous recombination between wheat chromosome 5D and barley chromosome 5H

Genome ◽

10.1139/g04-096 ◽

2005 ◽

Vol 48 (1) ◽

pp. 115-124 ◽

Cited By ~ 12

Author(s):

Shin Taketa ◽

Takaya Awayama ◽

Masahiko Ichii ◽

Makoto Sunakawa ◽

Tomoko Kawahara ◽

...

Keyword(s):

In Situ Hybridization ◽

Hordeum Vulgare ◽

Wheat Chromosome ◽

The Other ◽

Homoeologous Recombination ◽

Wheat Group ◽

Self Fertilization ◽

Homoeologous Relationships ◽

Group 5

Chromosome 5H of Hordeum vulgare 'New Golden' (NG) carries a gene(s) that accelerates heading in a wheat background. To introduce the early heading gene(s) of NG barley into the wheat genome, we attempted to induce homoeologous recombination between wheat and NG 5H chromosomes by 5B nullisomy. A nullisomic 5B, trisomic 5A, monosomic 5H plant (2n = 42) was produced from systematic crosses between aneuploid stocks of wheat group 5 chromosomes. A total of 656 F2 plants produced by self-fertilization were screened for recombinants by a PCR assay with 3 5H-specific amplicon markers. Twelve plants (1.8%) were selected as putative wheat–barley 5H recombinants. Five of them were inviable or sterile and the remaining 7 were fertile and subjected to the progeny test. Cytological analyses using fluorescence in situ hybridization and C-banding revealed that 6 of the 7 progeny lines are true homoeologous recombinants between the long arms of chromosomes 5D and 5H, but that the other one was not a recombinant having an aberrant barley telosome. The 6 cytologically confirmed recombinant lines included only 2 types (3 lines each), which were reciprocal products derived from exchanges at the same distal interval defined by two flanking markers. One type had a small 5HL segment translocated to the 5DL terminal, and the other type had a small terminal 5DL segment translocated to the 5HL terminal. In the latter type, the physical length of translocated barley segments slightly differed among lines. Homoeologous recombinants obtained in this study should be useful for further chromosome manipulation to introgress a small interstitial 5HL chromosome segment with the early heading gene(s) to wheat. Preferential occurrence of restricted types of recombinants is discussed in relation to homoeologous relationships between wheat and barley chromosomes.Key words: genomic in situ hybridization, homoeologous pairing, Hordeum vulgare, introgression, recombinant, Triticum aestivum.

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Methodology of gene transfer by homoeologous recombination into Triticum turgidum: transfer of K+/Na+ discrimination from Triticum aestivum

Genome ◽

10.1139/g92-096 ◽

1992 ◽

Vol 35 (4) ◽

pp. 639-646 ◽

Cited By ~ 45

Author(s):

J. Dvořák ◽

J. Gorham

Keyword(s):

Triticum Aestivum ◽

Salt Stress ◽

Triticum Turgidum ◽

Single Gene ◽

Large Population ◽

Wheat Chromosome ◽

Homoeologous Recombination ◽

Salt Stress Tolerance ◽

Recessive Mutant ◽

Or Genes

Triticum aestivum (2n = 6x = 42) differs from T. turgidum (2n = 4x = 28) by superior ability to exclude Na+ and accumulate K+ under salt stress. Chromosome 4D has a major affect on the enhancement of this trait in T. aestivum. To transfer this trait to T. turgidum, T. turgidum chromosome 4B was targeted for homoeologous recombination with chromosome 4D in the genetic background of T. turgidum, utilizing recessive mutant ph1c to enhance meiotic heterogenetic chromosome pairing. Since the basis of the genetic control of this trait by chromosome 4D was not known, a large population of random recombinant lines involving the alien chromosome and the wheat chromosome had to be produced. It was hypothesized that assaying lines in such a population for the trait would facilitate identification of those in which the gene or genes controlling the trait were incorporated into the T. turgidum chromosome. Forty lines with recombinant chromosomes were obtained. Thirty-nine recombination events involving chromosome 4D involved the targeted chromosome 4B. The ratio of K+/Na+ in leaves of plants grown under salt stress was determined for 27 lines. Nine lines showed enhanced K+/Na+ ratios. Evidence is presented that this trait is controlled by a single gene locus, designated here as Kna1. The locus is distal to the subterminal C-band in the long arm of chromosome 4D.Key words: wheat, linkage map distortion, salt stress tolerance.

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Homoeologous Recombination: A Novel and Efficient System for Broadening the Genetic Variability in Wheat

Agronomy ◽

10.3390/agronomy10081059 ◽

2020 ◽

Vol 10 (8) ◽

pp. 1059

Author(s):

Dal-Hoe Koo ◽

Bernd Friebe ◽

Bikram S. Gill

Keyword(s):

Recombination Frequency ◽

Crop Improvement ◽

Wheat Chromosome ◽

Wheat Crop ◽

Homoeologous Recombination ◽

Efficient System ◽

Wild Wheat ◽

Chromosome 5B ◽

Recombinant Frequency ◽

Ph1 Gene

Gene transfer from wild wheat relatives to bread wheat is restricted to homologous recombination. The presence of the Pairing homoeologous 1 (Ph1) gene in the long arm of wheat chromosome 5B allows only homologous chromosomes to pair and recombine, resulting in diploid inheritance of polyploid wheat. Previously, we identified a potent homoeologous pairing promotor gene(s) (Hpp-5Mg); its carrier chromosome 5Mg derived from Aegilops geniculata and its wheat homoeologous chromosome 5D freely recombined in the presence of the Ph1 gene. In this study, we investigated the effect of Hpp-5Mg on homoeologous recombination in the absence of Ph1. In Hpp-5Mg/ph1bph1b plants, we observed a vast genome-wide increase in homoeologous recombination and multiple crossovers (CO), including CO breakpoints in proximal regions of the chromosomes where recombination is known to be suppressed. We tested the efficacy of Hpp-5Mg/ph1bph1b-induced homoeologous recombination by producing new recombinants for the wheat streak mosaic virus resistance gene, Wsm3, present in the wheat-Thinopyrum intermedium Robertsonian translocation (RobT T7BS.7S#3L). A recombination frequency of 6.5% was detected by screening the progenies double monosomic for T7BS.7S#3L and 7B by genomic in situ hybridization. This recombination frequency was about 100-fold higher compared with the recombinant frequency of 0.06% observed by using ph1b-induced homoeologous recombination alone. Our results indicate that chromosome 5Mg promotes homoeologous recombination between wheat and wild wheat relative chromosomes, which helps in the generation of pre-breeding materials thereby accelerating wheat crop improvement.

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Gametocidal genes in wheat and its relatives. I. Genetic analyses in common wheat of a gametocidal gene derived from Aegilops speltoides

Canadian Journal of Genetics and Cytology ◽

10.1139/g84-013 ◽

1984 ◽

Vol 26 (1) ◽

pp. 78-84 ◽

Cited By ~ 24

Author(s):

H. Tsujimoto ◽

K. Tsunewaki

Keyword(s):

Common Wheat ◽

Chinese Spring ◽

Meiotic Chromosome ◽

Wheat Chromosome ◽

Female Fertility ◽

Aegilops Speltoides ◽

Alloplasmic Lines ◽

Male Gametes ◽

First Case ◽

Gametocidal Gene

Alloplasmic lines of 12 common wheats carrying G-type cytoplasm derived from an aucheri-type strain of Aegilops speltoides show about 50% reduction of female fertility compared with the alloplasmic lines of the same common wheats carrying G-type cytoplasms from other sources. This reduction of female fertility is caused by a gametocidal gene derived from Ae. speltoides. This gene has been preferentially transmitted through 16 successive backcrosses in which common wheat was the recurrent pollen parent, and has been present in the heterozygous state in every backcross generation. The karyotype and meiotic chromosome pairing of hybrid from reciprocal crosses between (Ae. speltoides) – cv. Chinese Spring and (Triticum aestivum) – cv. Chinese Spring are normal, indicating that the gametocidal gene derived from an Ae. speltoides chromosome subsequently was translocated to a wheat chromosome. This is the first case reported of the integration of a gametocidal gene into a wheat genome; the symbol given to it is Gcl. The F1 female and male gametes not carrying this gene abort and, consequently, all F2 progeny are homozygous for the gene and fully fertile. The origin and distribution of the Gcl gene and its potential use for hybrid wheat production have been discussed.

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Introgression of Thinopyrum elongatum DNA fragments carrying resistance to fusarium head blight into Triticum aestivum cultivar Chinese Spring is associated with alteration of gene expression.

Genome ◽

10.1139/gen-2020-0152 ◽

2021 ◽

Author(s):

Aparna Haldar ◽

Farideh Tekieh ◽

Margaret Balcerzak ◽

Danielle Wolfe ◽

DaEun Lim ◽

...

Keyword(s):

Gene Expression ◽

Fusarium Head Blight ◽

Wheat Chromosome ◽

Wheat Breeding ◽

Resistance Locus ◽

Head Blight ◽

Breeding Programs ◽

Expression Of Genes ◽

Fhb Resistance ◽

Thinopyrum Elongatum

The tall wheatgrass species Thinopyrum elongatum carries on the long arm of its chromosome 7E a locus contributing strongly to resistance to fusarium head blight (FHB), a devastating fungal disease affecting wheat crops in all temperate areas of the world. Introgression of Th. elongatum 7E chromatin into chromosome 7D of wheat was induced by the ph1b mutant of CS. Recombinants between chromosome 7E and wheat chromosome 7D, induced by the ph1b mutation, were monitored by a combination of molecular markers and phenotyping for FHB resistance. Progeny of up to five subsequent generations derived from two lineages, 64-8 and 32-5, were phenotyped for FHB symptoms and genotyped using published and novel 7D- and 7E-specific markers. Fragments from the distal end of 7EL, still carrying FHB resistance and estimated to be less than 114 and 66 Mbp, were identified as introgressed into wheat chromosome arm 7DL of progeny derived from 64-8 and 32-5, respectively. Gene expression analysis revealed variation in the level of expression of genes from the distal ends of 7EL and 7DL in the introgressed progeny. The 7EL introgressed material will facilitate use of the 7EL FHB resistance locus in wheat breeding programs.

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