Authors: Taketa Shin; Awayama Takaya; Ichii Masahiko; Sunakawa Makoto; Kawahara Tomoko; Murai Koji

Source: Genome, Volume 48, Number 1, February 2005 , pp. 115-124(10)

Publisher: NRC Research Press

Abstract:

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.

Le chromosome 5H de Hordeum vulgare 'New Golden' (NG) porte un ou des gènes qui accélèrent l'épiaison chez le blé. Afin d'introduire des gènes pour la précocité chez le blé, les auteurs ont tenté d'induire des échanges homéologues entre les chromosomes du blé et le chromosome 5H de NG en faisant appel à la nullisomie 5B. Une plante nullisomique 5B, trisomique 5A et monosomique 5H (2n = 42) a été produite à la suite de croisements systématiques entre lignées aneuploïdes pour des chromosomes 5 du blé. Au total, 656 plantes F₂ obtenues par autofécondation ont été criblées pour des recombinants au moyen d'un test PCR avec trois marqueurs spécifiques du chromosome 5H. Douze plantes (1,8 %) ont été identifiées comme étant potentiellement des recombinants blé–orge 5H. Cinq de celles-ci étaient non-viables ou stériles, alors que les sept autres étaient fertiles et leur descendance a été examinée. Des analyses cytologiques par hybridation in situ en fluorescence et coloration des bandes C ont révélé que six des sept lignées sont véritablement des recombinants homéologues entre les bras longs des chromosomes 5D et 5H, tandis que la dernière lignée n'était pas un recombinant, mais portait plutôt un télosome d'orge aberrant. Les six lignées recombinantes validées par examen cytologique ne comprenaient que deux types d'événements (trois lignées de chacun) et ceux-ci constituaient les produits réciproques issus d'échanges survenus dans le même intervalle distal délimité par deux marqueurs. Un type d'événement était caractérisé par la translocation d'un segment de 5HL sur l'extrémité de 5DL, tandis que l'autre type montrait un petit segment de 5DL au bout du chromosome 5HL. Dans ce dernier cas, la taille physique des segments chromosomiques d'orge échangés était légèrement différente d'une lignée à l'autre.

Document Type: Research article

Publication date: 2005-02-01

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• From its inception in 1957, this international cytogenetics journal has catered to the research areas of the members of the Genetics Society of Canada; traditionally, these have included agriculture, entomology, genetics/cytogenetics, and evolutionary mechanisms. The contents of the journal have evolved as contributors developed new technologies and interests. A 20-member Editorial Board is composed of scientists from around the world. Reviews and commentary from respected experts are often featured.
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