BGS 512, Reaction to Puccinia graminis 2 (wheat stem rust), Rpg2

Resistance to Puccinia graminis tritici = T2 (5).
Resistance to Puccinia graminis Pers. f sp tritici Eriks. & E Henn. = Rpg2b (4).

Monofactorial dominant (6. 9). incomplete dominant to race QCC (3).
Located in chromosome 2HL (1, 2); Rpg2.b is in a 2 cM region proximal from the Eam6 (Early maturity 6 or Praematurum-c) locus and is near the centromere (1, 2).

Moderate resistance to some races of Puccinia graminis f. sp. tritici is conferred by the Rpg2.b gene. Percent stem and leaf sheath infection and lesion size in adult plants are reduced compared with susceptible plants under field conditions (6, 9, 11). Patterson (6) used linkage data to demonstrate that the Rpg2 locus differs from the Rpg1 locus. Hietpas 5 exhibits a moderate-to-high level of adult plant resistance (APR) to races QCCJB and MCCFC and a mostly susceptible seedling phenotype (1). Seedling tests with wheat and rye stem rust isolates were ineffective in rapidly detecting resistance conferred by Hietpas 5 (12). Hietpas 5 had low adult plant reactions to African stem rust isolates TTKSK and PTKST (10).

A spontaneous mutant in Oderbrucker (CIho 4666) isolated in Wisconsin, USA by Mr Hietpas and named Hietpas 5 (CIho 7124, GSHO 1584) (6, 9).

Rpg2.b in Hietpas 5 (CIho 7124, GSHO 1584) (6). Rpg2.b is likely associated with the QTL Rpg-qtl-HH-Hie-2H.3 QTL, reported in wild barley by Sallam et al., (8) in chromosome 2H (2).

Rpg2.b in Hietpas 5 (CIho 7124, GSHO 1584).

1. Case, A., 2017. Genetics, sources, and mapping of stem rust resistance in barley. Ph.D. Dissertation, University of Minnesota, St. Paul, MN.
2. Case, A.J., S. Bhavani, G. Macharia, Z. Pretorius, V. Coetzee, F. Kloppers, P. Tyagi, G. Brown‑Guedira, and B.J. Steffenson. 2018. Mapping adult plant stem rust resistance in barley accessions Hietpas‑5 and GAW‑79. Theor. Appl. Genet. 131:2245-2266.
3. Fox, S.L., and D.E. Harder. 1995. Resistance to stem rust in barley and inheritance of resistance to race QCC. Can J. Plant Sci. 75:781-788.
4. Franckowiak, J.D. 1991. BGS 512, Resistance to Puccinia graminis Pers. f. sp. tritici Eriks. & E. Henn., Rpg2b. Barley Genet. Newsl. 20:116.
5. Miller, J.D., and J.W. Lambert. 1955. Variability and inheritance of reaction of barley to race 15B of stem rust. Agron. J. 47:373-377.
6. Patterson, F.L. 1951. Adult plant and seedling reactions of barley varieties and hybrids to 3 races of Puccinia graminis tritici. Ph.D. Thesis. Univ. of Wisconsin, Madison.
7. Patterson, F., R. Shands, and J. Dickson. 1957. Temperature and seasonal effects on seedling reactions of barley varieties to three races of Puccinia graminis f. sp. tritici. Phytopathology 47:395-402.
8. Sallam, A.H., P. Tyagi, G. Brown-Guedira, G.J. Muehlbauer, A. Hulse, and B.J. Steffenson. 2017. Genome-wide association mapping of stem rust resistance in Hordeum vulgare subsp. spontaneum. G3 Genes Genomes Genet. 10:3491-3507.
9. Shands, R.G. 1964. Inheritance and linkage to stem rust and loose smut resistance and starch type in barley. Phytopathology 54:308-316.
10. Steffenson, B.J., A.J. Case, Z.A. Pretorius, V. Coetzee, F.J. Kloppers, H. Zhou, Y. Chai, R. Wanyera, G. Macharia, S. Bhavani, and S. Grando. 2017. Vulnerability of barley to African pathotypes of Puccinia graminis f. sp. tritici and sources of resistance. Phytopathology 107:350-362.
11. Steffenson, B.J., R.D. Wilcoxson, and A.P. Roelfs. 1985. Resistance of barley to Puccinia graminis f. sp. tritici and Puccinia graminis f. sp. secalis. Phytopathology 75:1108-1111.
12. Sun, Y., and B.J. Steffenson. 2005. Reaction of barley seedlings with different stem rust resistance genes to Puccinia graminis f. sp. tritici and Puccinia graminis f. sp. secalis. Can. J. Plant Pathol. 27:80-89.

J.D. Franckowiak. 1991. Barley Genet. Newsl. 20:116.

J.D. Franckowiak and B.J. Steffenson. 1997. Barley Genet. Newsl. 26:439.
J.D. Franckowiak. 2018. Barley Genet. Newsl. 48:152-153.