Disease resistance. Leaf rust
Lr47
Background information
The leaf rust resistance gene Lr47 confers resistance to a wide spectrum of leaf rust strains. This gene was transferred from chromosome 7S of Triticum speltoides to chromosome 7A of Triticum aestivum. Initially, the RFLP locus Xabc465 was used to follow the transfer of the segment containing Lr47 (1), but later, this marker was converted into a dominant PCR marker. To detect the allele present in 7A, a cleavege amplified polymorphic sequence (CAPS) marker was developed. Using both markers, homozygous and heterozygous individuals for Lr47 can be discriminated.
Methods
Since the T. speltoides segment containing Lr47 generally will not recombine in the presence
of a wild-type Ph1, only one marker is needed to
determine the presence of the whole segment. The primers specific for T. speltoides are
PS10R and PS10L, which produce a band of 282 bp (see protocol).
To differentiate homozygous from heterozygous Lr47 plants
a CAPS marker was developed that is specific for the 7A allele of the
Xabc465 locus. This marker is detected using primers PS10R and PS10L2 and then digesting with
Sac I (see protocol).
The experimental procedures are described in detail in Ref.2.
Available germplasm
A wheat germplasm with intersticial translocations from chromosome 7S of T. speltoides was developed to transfer the Lr47 gene into wheat. The translocated segment is 20 to 30 cM long and is located on chromosome 7A, 2 to 10 cM from the centromere.
The original germplasm for hard white spring was obtained in Pavon after three backcrosses following homoeologous recombination. The identification of this line is PI 603918. For more information see Ref. 3. Seed samples of this translocation line have been deposited in the USDA-ARS National Small Grain Collection P.O. Box307, Aberdeen, ID 83210. Small quantities can be obtained for research and breeding purposes from the curator of the National Small Grain Collection. Transfer of Lr47 from Pavon+Lr47 into HRS Yecora Rojo has been completed after six backcrosses, seeds of this line for crosses can be obtained from Jorge Dubcovsky (ask for UC996610010, Yecora Rojo/Pavon Lr47).
Current backcrossing programs for Lr47 within the project
| Donor | Recurrent Parent | Laboratory code | Market class |
|---|---|---|---|
| HRS Yecora Rojo - Lr47 | MN97695 | MN | HRS |
| HRS Yecora Rojo - Lr47 | MN95002 | MN | HRS |
| HRS Yecora Rojo - Lr47 | MN97803 | MN | HRS |
| PI603918 | Hank | MT | HRS |
| PI603918 | MT9874 | MT | HRS |
| PI603918 | MT9929 | MT | HRS |
| PI603918 | Scholar | MT | HRS |
| PI603918 | McNeal | MT | HRS |
| PI603918 | MTHW9710 | MT | HWS |
| HRS Yecora Rojo - Lr47 | 97395 | IN | SRW |
| HRS Yecora Rojo - Lr47 | 961341 | IN | SRW |
| HRS Yecora Rojo - Lr47 | Goldfield | IN | SRW |
| HRS Yecora Rojo - Lr47 | 9346 | IN | SRW |
| HRS Yecora Rojo - Lr47 | 92201 | IN | SRW |
| PI603918 | 981477 | IN | SWW |
Laboratory codes: MN, University of Minnesota; MT, Montana State University; IN, Purdue University.
Known problems
None reported to date.
References
1.Molecular characterization of two Triticum speltoides interstitial translocations carrying leaf rust and greenbug resistance genes. Dubcovsky, J.; Lukaszewski, A. J.; Echaide, M.; Antonelli, E. F.; Porter, D. R. In: Crop Science Nov.-Dec., 1998. 38 (6): 1655-1660.[abstract]
2.Development of PCR markers for wheat leaf rust resistance gene Lr47. Helguera, M.; Khan, I. A.; Dubcovsky, J. In: Theoretical and Applied Genetics September, 2000. 101 (4): 625-631. [abstract]
3.Registration of two germplasms of common wheat with interstitial translocations of Triticum speltoides carrying leaf rust and greenbug resistance genes. Lukaszewski, A. J.; Porter, D.R.; Antonelli, E. F.; Dubcovsky, J.In: Crop Science Mar.-Apr., 2000. 40:590.