Disease resistance. Stripe rust.

Yr15

Background information

In 1970, Gerechter-Amitai and Stubbs (1) reported that accession G-25 of Triticum dicoccoides Korn was resistant to many races of Puccinia striiformis from different geographical origins. Later, it was shown that this stripe rust resistance was conferred by the dominant gene Yr15 (2,3). McIntosh and Silk showed that it is located on the short arm of chromosome 1B (4). Yr15 was introgressed into tetraploid and hexaploid wheats (2, 5). Xianming Chen informed that after several years of greenhouse and field testing, no virulent isolates on Yr15  have been detected (Xianming Chen, personal communication)

Methods

There are different molecular markers available for Yr15, mainly RFLPs and microsatellites. Different programs within the IFAFS project have found that some of the markers are not polymorphic for their populations. However, there are several markers close to Yr15 that can be tested. Peng et. al (6) published a high density map of the chromosome region where Yr15 is located. For a map and distances see fig. 2 of ref. 6. The table below shows some of the closer markers with the relatives distances to Yr15 and a link to Graingenes.:

The University of California program started the introgression of Yr15 with RFLP markers XTri and Xcdo1173 but is currently using flanking microsatellite loci Xbarc8 and Xgwm273.

Microsatellite loci Xbarc8 and Xgwm273. PCR products were separated on 6% polyacrylamide geles and stained with ethidium bromide. References: A, Avocet; Y, Avocet/Yr15; 1-5 F1 plants of a cross between Dirkwin and Avocet/Yr15; U, UC1419; 6-13: plants from a backcross between UC1419 and Avocet/Yr15. Plants 6, 7, 11 and 12 are homozygous for the UC1419 allele, plants 8 and 13 are heterozygous and plants 9 and 10 recombined between the flanking markers.

XTriplet (digested with Dra I)	Xcdo1173 (digested with EcoR V)

References

1. A valuable source of yellow rust resistance in Israeli population of wild emmer Triticum dicoccoides  Koern. Gerechter-Amitai ZK, Stubbs RW.  In: Euphytica, 1970, 19:12-21.

2. Inheritance of resistance to stripe rust (Puccinia striiformmis) in crosses between wild emmer (Triticum dicoccoides) and cultivated tetraploid and hexaploid  wheat. I. Triticum durum. Gerechter-Amitai ZK, Grama A.  In: Euphytica, 1974. 23:387-392.

3. Yr15: A new gene for resistance to Puccinia striiformis in Triticum dicoccoides sel. G-25. Gerechter-Amitai ZK, Van Silfhout CH, Grama A, Kleitman F. In:  Euphytica, 1989, 43(1-2):187-190. [abstract]

4. Cytogenetic studies in wheat XVII. Monosomic analysis and linkage relationships of gene Yr15 for resistance to stripe rust. McIntosh RA, Silk J, The TT. In: Euphytica, 1996, 89(3):395-399. [abstract]

5. Inheritance of resistance to stripe rust (Puccinia striiformmis) in crosses between wild emmer (Triticum dicoccoides) and cultivated tetraploid and hexaploid  wheat. I. Grama A, Gerechter-Amitai ZK.   In: Euphytica, 1974. 23:393-398.

6. High-density molecular map of chromosome region harboring stripe-rust resistance genes YrH52 and Yr15 derived from wild emmer wheat, Triticum dicoccoides.. Peng JH, Fahima T, Roeder MS, Huang QY. Dahan A, Li YC, Grama A, Nevo E. In: Genetica, 2000, 109(3): 199-210. [abstract]