Plant & Animal Genomes XIII Conference

January 15-19, 2005
Town & Country Convention Center
San Diego, CA

Towards Isolation Of Boron Tolerance Genes In Wheat And Barley

Thorsten Schnurbusch¹ , Tim Sutton¹ , Jeff Paull² , Sansanee Jamjod² , Anthony Rathjen² , Peter Langridge¹ , Nick Collins¹

¹  Australian Centre for Plant Functional Genomics (ACPFG), The University of Adelaide, Waite Campus, PMB1, Glen Osmond, SA 5064, Australia

²  The University of Adelaide, Waite Campus, Department of Plant & Pest Science, School of Agriculture & Wine, PMB1, Glen Osmond, SA 5064, Australia

Toxic levels of subsoil boron (B) impose severe limitations to cereal production in Australia. Breeding and research programs at the University of Adelaide, Waite Campus, had identified a major B tolerance locus distally on the long arm of chromosome 7B, in both bread wheat (Euphytica, Paull et al. (1991) 55:217-228; Theor Appl Genet, Jefferies et al. (2000) 101:767-777) and durum wheat (S. Jamjod, PhD thesis). Alignment of the genetic maps using common RFLP markers revealed a close similarity in the positions of B tolerance loci in the two species, suggesting that the genes are ortholgous. Doubled-haploid populations characterized for B tolerance will be used to obtain moderate mapping resolution in bread wheat, and larger F2 and F3 populations are being developed for high-resolution mapping. QTL analysis in barley revealed a major toxicity tolerance locus on the long arm of chromosome 4H and a moderate tolerance locus on chromosome 6H (Theor Appl Genet, Jefferies et al. (1999) 98:1293-1303). In order to achieve targeted PCR-marker generation in all species for fine-mapping, we are exploiting the barley and wheat EST sequence database and genes identified within the rice (Oryza sativa L.) genomic sequence from the co-linear region (rice chromosome 2, 3 and 6). Together with the construction of an in-house BAC (Bacterial Artificial Chromosome) library of B tolerant lines, this will enable map-based isolation of these genes in barley as well as wheat and subsequent determination of the molecular mechanisms underlying B tolerance in cereals.