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

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.

Chromosomal assignment and deletion mapping of barley EST markers

“…* * * * * * * * * k03353 i-f * * * * * * * * * * * * * * k00901 f-p * * * * * * * * * * * * * * * k00471 f-p * * * * * * * * * * * * * * * k02344 f-p * * * * * * * * * * * * * * * k02414 f-p * * * * * * * * * * * * * * * k00896 p-c * * * * * * * * * * * * * * * * * k04944 p-c * * * * * * * * * * * * * * * * k02558 p-c * * * * * * * * * * * * * * * * * k03148 c-* * * * * * * * * * * * * * * * * * k02620 c-* * * * * -* * * * * * * * * * * * k01578 c-* * * * * * * * * --* * * * * * * genetic stocks for arranging barley EST markers along the chromosomes. The EST markers assigned to subarm regions would be useful for comparing physical and genetic maps of barley chromosomes (Künzel et al 2000), and also for detecting the barley chromosome segments introduced into wheat (Taketa et al 2005). …”

Dissection of barley chromosome 3H in common wheat and a comparison of 3H physical and genetic maps

“…Attempting to transfer genes from barley to wheat, some researchers applied homoeologous pairing to induce wheat-barley recombinant chromosomes (Islam and Shepherd, 1992;Sherman et al, 2001;Murai et al, 1997;Taketa et al, 2005). Thus, barley has been a model plant of chromosome engineering in cereals.…”

Dissection of barley chromosome 5H in common wheat

“…Attempting to transfer genes from barley to wheat, some researchers isolated wheat-barley recombinant chromosomes that were induced by homeologous pairing (Islam and Shepherd 1992;Sherman et al 2001;Murai et al 1997;Taketa et al 2005).…”