GrainGenes

Coordinator’s report: Chromosome 5H (7)

George Fedak

Eastern Cereal and Oilseed Research Centre

Agriculture and Agri-Food Canada

Ottawa, Ontario K1A 0C6 Canada

Hard-copy edition pages 147 - 148.

Shaw and Gill, 2000 have developed a high density physical map of the middle region of the long arms of chromosome 5B of wheat and chromosome 7 (5H) of barley by comparative mapping. This zone contains the Ph1 locus of wheat and Mlj Lysl, Ale and numerous other genes of barley ie this is a gene-rich area of the genome. Thirteen markers were found to be common between the homologous regions of two maps and were found to be in the same order except for one marker. Recombination in the region was very high.

Barley RGA family homologues were isolated from barley using as a probe the pic 20 sequence from the maize Rpl-D gene (Rostoks et al., 2000). The probe cosegregated with the barley stem rust resistance gene Rpg1. A total of 9 pic 20 homologues were isolated from barley. One of them mapped to Bin 1 on chromosome 7 (5H) that is flanked by marker ABG704-ABG320.

Brueggeman et al., 2000 tried several different methods for generating RGAs from various sources of barley DNA: 1. hybridization of NBS-derived oligonucleotides to arrayed BAC and cDNA libraries, 2. PCR amplification of RGAs from BAC DNA pools and 3. PCR amplification from cDNA libraries. A total of 13 new RGAs were synthesized and 5 mapped to loci on chromosome 7 (5H).

The locus rpg4 conferring resistance to the QCC race of stem rust is located on chromosome 7 (5H). It has now been localized on two overlapping BAC clones that cover an estimated 300 kb region of the long arm of that chromosome (Druka et al., 2001).

Puroindoline genes pin A and pin B control endosperm hardness in wheat and barley. In wheat, the locus is present as a single copy and maps to the distal part of chromosome 5D only. In barley, pin. B is a multigene family located on chromosome 7 (5H) and has three distinct sequence types. It has been shown that the multiple copies are expressed (See et al., 2001) but thus far recombination has not been detected between them.

QTL for crossability of H. bulbosum with barley were mapped onto H. bulbosum chromosomes 2Hb, 3Hb, 6Hb and 7Hb. A novel QTL controlling subsequent hybrid embryo formation, which explains 40% of the variability was mapped onto chromosome 6Hb (Salvo-Gaindo et al., 2001).

Fermentality as a component of the process for whisky production is controlled by QTL, one of which is located on chromosome 7 (5H) (Swanston et al., 1999).

There are strong interactions between the hulless gene and coleoptile lengths. At least 3 QTL have been identified for coleoptile length. The one from the cross Galleon/Haruna Nijo is located on chromosome 5H (Box and Barr, 2000).

References

Box, A.J. and A.R. Barr. 2000. Identification of molecular markers associated with improved coleoptile length in hulless barley. In S. Logue (ed.) Barley Genetics VIII. Proc. Eighth Int. Barley Genetics Symp., Adelaide, South Australia 2000. Dept. Plant Science Waite Campus, Adelaide University, Glen Osmond, South Australia 5064. Volume III: 11-13.

Brueggeman, R., D. Kudrna, and A. Kleinhofs. 2000. Efficient cloning of resistant gene analyses from barley. BGN 31: 24.

Druka, A., Kudrna, N. Rostoks, B. Steffenson, and A. Kleinhofs. 2001. Progress in cloning barley rpg4 gene. Plant and Animal Genome IX: poster 108.

Rostoks, N., J.M. Zale, J. Soule, R. Brueggeman, A. Druka, D. Kudrna, and A. Kleinhofs.  2000. Barley gene family homologous to maize rust resistance gene Rpl-D. BGN 31: 21.

Salvo-Garrido, H., l. Fisk, D. Laurie, and J. Snape. 2001. QTL analysis in Hordeum bulbosum L. for interspecific crossability and hybrid formation in barley. Plant and Animal Genome IX poster no. 420.

See, D.R., V. Kanozin, B. Beecher, M. Giroux, and T. Blake. 2000. Puroindoline B, a multigene family in barley. Plant and Animal Genome IX: poster 413.

Shah, M.M. and K.S. Gill. 2000. High density mapping of a gene-rich region present on homoelogous group 5L of wheat and barley. BGN 31: 18.

Swanston, J.S., W.T.B. Thomas, W. Powell, G.R. Young, P.E. Laurence, L. Ramsay, and R. Waugh. 1999. Using molecular markers to determine barleys most suitable for malt whiskey distilling. Molecular Breeding 5: 103-109.