Establishment of 14 wheat lines carrying telosomes of barley chromosome 7H


Kazuhiko Sakai, Takashi R. Endo, and Shuhei Nasuda

Laboratory of Plant Genetics, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan

Corresponding author: Shuhei Nasuda


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The wheat (Triticum aestivum cv. Chinese Spring, 2n=6x=42, genome formula AABBDD)–barley (Hordeum vulgare cv. Betzes, 2n=2x=14, HH) addition lines (Islam et al. 1981) are useful to allocate genes and DNA markers to each barley chromosome. We have shown that the barley chromosomes added to wheat are susceptible to chromosome breakage genetically induced by gametocidal (Gc) chromosomes (Shi and Endo 1997, 1999, 2000; for review see Endo (2007)). To date, we have developed the barley chromosome dissection lines for chromosomes 3H (Sakai et al. submitted), 5H (Ashida et al. 2007), and 7H (Serizawa et al. 2001; Masoudi-Nejad et al. 2005; Nasuda et al. 2005b). These wheat lines carrying dissected barley chromosomes are powerful materials for the allocation of DNA markers to sub-arm regions of the individual barley chromosomes. For chromosome 7H, we have developed 19 stocks of Chinese Spring wheat carrying structurally modified 7H chromosomes (Nasuda et al. 2005b). The breakpoints of the modifications (deletions or translocations) are in various regions of chromosome 7H; eight each on the short and long arms, and three in the pericentromeric region. Two telosomes of the 7HS do not have centromeric repeats that are ubiquitous in the primary constrictions of all normal barley chromosomes (Nasuda et al. 2005a). PCR analysis of the EST markers in these lines allowed us to define seven and six bins on 7HS and 7HL, respectively.

Here, we report the establishment of additional 14 novel 7H-disecction lines that have breakpoints in the pericentromeric region. They were originally isolated from the 7H addition line of Chinese Spring carrying a Gc chromosome (2C) from Aegilops cylindrica (Shi and Endo 2000). In short, we made crosses between two disomic addition lines of common wheat carrying chromosome 7H (Islam et al. 1981) and a gametocidal (Gc) chromosome 2C from Aegilops cylindrica (2n=4x=28, DDCC) (Endo 1988), respectively. The F1 hybrids (21”+1’7H+1’2C ) were backcrossed to the 7H addition line to produce BC1 plants that were disomic for 7H and monosomic for 2C (2n=45, 21”+1”7H+1’2C). The BC1 plants were then self-pollinated or cross-pollinated with CS to generate structural changes involving the 7H chromosome. We selected plants with telocentric chromosomes of 7H from the progeny of BC1 by simultaneous genomic in situ hybridization (GISH) with barely genomic DNA probe and fluorescence in situ hybridization (FISH) with the subtelomeric repeat HvT01 (Belostotsky and Ananiev 1990). We identified the chromosome arm retained in the lines by C-banding. Wheat lines carrying telocentric chromosome were grown to maturity and crossed with normal Chinese Spring to isolate single modified chromosomes. So far, we obtained nine telosomes for the short arm of 7H (7H-5b, 7H-27, 7H-29St, 7H-37, 7H-80, 7H-82b, 7H-85St, 7H-105, and 7H-122) and five for the long arm (7H-6Lt, 7H-31Lt, 7H-61, 7H-83, and 7H-127). Most of the lines appear to be telocentric chromosomes in cytological analysis (Figure 1). The telosomes for the short arm had the centromeric C-band diagnostic to 7HS, while the 7HS** chromosome reported in Nasuda et al. (2005a) lacks it (Figure 1). The telosomes of the long arm also had the centromeric C-bands. Chromosome 7H-61 appeared to be acrocentric in cytological observation, which was confirmed by the presence of a DNA marker locating on the short arm (Sakai et al. unpublished). All the lines are either homozygous or hemizygous for the critical 7H telosomes, so that they can be readily used for molecular mapping. These lines will be deposited in the National BioResource Project-Wheat, Japan ( Together with the 7HS and 7HL telocentric lines developed by Islam et al. (1981) and by Nasuda et al. (2005b), there are now 19 wheat lines carrying barley 7H telosomes available. These lines will be very useful for analysis of genes and markers in the centromeric region of 7H, where genetic recombination is greatly suppressed (Kunzel et al. 2000).


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