Disease resistance. Leaf rust.

Lr21

Contributed by Allan Fritz

Background information

Aegilops tauschii, the D-genome progenitor of common wheat (Triticum aestivum), has been a rich source for resistance to Puccinia triticina. To date, six named genes have been described (reviewed in ref. 1, 2). One of the first genes transferred was Lr21 (3). This gene appears to be common in Ae. tauschii, as it has been transferred from several different accessions to T. aestivum (4). The data from Huang and Gill (4) indicate that Lr21 and Lr40 are allelic.

While this gene has been known for some time, it has not been widely used. According to the Cereal Disease Laboratory’s database, the only North American cultivar that carries Lr21 is AC Cora (see the Rust Resistance Genes in Wheat Lines and Cultivars Database). Lr21 provides resistance to the current spectrum of P. triticina races in the Southern Great Plains. There are no confirmed reports of virulence to Lr21. Recently, Huang and Gill (4) reported a PCR-based marker that co-segregates with all reported sources of Lr21.

Methods

Talbert et al. (5) developed a PCR method based on the sequence of RFLP clone KSUD14. You can find an alternative protocol for Lr21 using an STS marker on the electronic lab manual of the Wheat Genetics Resource Center at Kansas State University.

Available germplasm

KS94U215 is the donor used by the backcrossing programs within the IFAFS project. The line has not been formally released, but is available upon request. Requests can be addressed to Allan Fritz or to Gina Brown-Guedira.
There are other possible sources for transferring Lr21: KS86WGRC02 (HRW), KS89WGRC07 (HRW), KS92WGRC15 (HRW) and AC Cora (HRS).

References

1. Leaf rust-resistance genes Lr41, Lr42 and Lr43 transferred from Triticum tauschii to common wheat. Cox, T.S.; Raupp W.J.; Gill, B.S. In: Crop Science, 1994, 34(2):339-343. [abstract]

2. Chromosome location of leaf rust resistance gene Lr43 from Aegilops tauschii in common wheat. Hussien, T.; Bowden, R.L.; Gill, B.S.; Cox, T.S. In: Crop Science, 1997, 37(6):1764-1766.[abstract]

3. Inheritance in hexaploid wheat of leaf rust resistance and other characters derived from Aegilops squarrosa. Kerber, E.R.; Dyck, P.L. In: Canadian Journal of Genetics and Cytology, 1969, 11:639-647.

4. An RGA-like marker detects all known Lr21 leaf rust resistance gene family members in Aegilops tauschii and wheat. Huang, L; Gill, B.S. In: Theoretical and Applied Genetics, 2001, 103(6-7):1007-1013. [abstract]

5. Evaluation of "sequence-tagged-site" PCR products as molecular markers in wheat. Talbert, L.E.; Blake, N.K.; Chee, P.W.; Blake, T.K.; Magyar, G.M. In: Theoretical and Applied Genetics, 1994, 87(7):789-794. [abstract]