EGRAM: The European comparative gramineae mapping programme

• Research unit: EU RFP
• Project number: 97.0208

Key words (English)

Wheat; leaf rust; resistance; fungal disease; LR1

Alternative project number (English)

EU project number: BIO4CT972220

Research programs (English)

EU-programme: 4. Frame Research Programme - 4.1 Biotechnology

Short description (English)

See abstract

Partners and International Organizations (English)

John Innes Centre, Norwich; Institut für Pflanzengenetik und Kulturpflanzenforschung, Gatersleben; Plant Breeding Institute, Cambridge; CIRAD/ORSTOM Montpellier; the Sainsbury Lab, Norwich; MPI für Züchtungsforschung, Kain; Agricultural University of Norway, Aas; DvP DJ Van Der Have BV (NL)

Abstract (English)

The goal of our project is to isolate the Lr1 leaf rust disease resistance gene by map-based cloning or by approaches based on homology with known resistance genes. In the third year of the EGRAM collaboration, we have continued to concentrate on the genetic high resolution mapping of the Lr1 locus of wheat with enlarged mapping populations and on physical mapping of the Lr1 gene using genomic BAC and YAC libraries of barley and Triticum tauschii (D genome).
For genetic fine mapping, 2826 F2 plants of the cross ThatcherLr1 x Thatcher and 832 F2 plants of the cross ThatcherLr1 x Frisal have been analysed with four RFLP markers PSR567, BCD1421, pTAG621, ABC718 and three microsatellite markers GWM269, GWM272 and GWM654. A high resolution map in the region of the Lr1 locus has been constructed. The Lr1 gene was mapped between the RFLP markers ABC718 and PSR567. The two markers are very tightly linked to the Lr1 gene and the genetic distance is 0.12 cM and 0.05 cM, respectively. The RFLP marker pTAG621 was located at about 0.53 cM from the resistance gene. The microsatellite markers GWM269 and GWM654 were mapped to one locus at about 6.1 cM and BCD1421 is at about 11.7 cM away from the Lr1 gene proximal to the centromere.
The RFLP marker ABC718 from barley is a single copy sequence in diploid barley and T. tauschii and is very tightly linked with the target gene in wheat. Chromosome walking to the Lr1 gene has been started from this marker using a genomic BAC library of T. tauschii and barley BAC and YAC libraries. Five BAC clones from the T. tauschii-genomic BAC library, six from a barley-genomic BAC library and one YAC clone from a YAC library of barley were isolated with ABC718. The five BAC clones isolated from T. tauschii-BAC library contain genomic inserts of about 85-100 kb and cover about 150 kb of the genome region around the ABC718 locus. BAC ends were isolated by plasmid rescue and analysed. Most of the BAC ends are repetitive sequences and could not be used for mapping. One BAC end B14RE is about 1.6 kb in length and a single copy in the wheat genome. Analysis of this BAC end in our mapping population showed that it cosegregated with the probe ABC718. A low copy fragment from the end region of the other side of this BAC clone has been isolated and it also cosegregated with ABC718. End probes isolated from BAC and YAC clones of genomic barley libraries represented repetitive sequences or were therefore not hybridized with genomic DNA of wheat. Thus, none could not be used for physical mapping. Physical walking to the Lr1 gene from the other side of the gene starting with the RFLP marker PSR567 is in progress and the cloning of the gene seems to be within reach.

References in databases (English)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 97.0208