International Database for Barley Genes and Barley Genetic Stocks

BGS 738, Required for resistance to Cochliobolus sativus 2, rcr2

BGN  45:250
Stock number: BGS 738
Locus name: Required for resistance to Cochliobolus sativus 2
Locus symbol: rcr2

Previous nomenclature and gene symbolization:

γ08-123; (R14-40) (2).


Monofactorial recessive (2, 3).
Location is unknown.


Plants with the rcr2.b mutant at the rcr2 locus exhibit a susceptible reaction following inoculation with Cochliobolus sativus (Ito & Kurib.) Drechs. ex Dastur [anamorph: Bipolaris sorokiniana (Sacc.) Shoem.] isolate ND85F. When rated following inoculation at the seedling stage, 10 individual plants of the rcr2.b mutant stock ranged from 3.5 to 4.5 with a mean 4.0 compared to rating of 3.5 to 4.5 with a mean of 3.7 for its moderately resistant parent Morex (2, 3). The six-rowed spring barley cultivar Morex has been reported to have the Rcs5.e (Reaction to Cochliobolus sativus 5) gene and at least two other QTL that in combination confer resistance to C. sativus (1, 4, 5).
No images

Origin of mutant:

A gamma-ray induced mutant in Morex (CIho 15773) (2).

Mutational events:

A gamma-ray induced mutant in Morex (CIho 15773) (2).

Mutant used for description and seed stocks:

rcr2.b (γ08-123; R14-40, GSHO 3703) in Morex.


1. Bilgic, H., B.J. Steffenson, and P.M. Hayes. 2005. Comprehensive genetic analyses reveal differential expression of spot blotch resistance in four populations of barley. Theor. Appl. Genet. 111:1238-1250.

2. Kleinhofs, A. (Unpublished).

3. Steffenson, B.J. (Unpublished).

4. Steffenson, B.J., P.M. Hayes, and A. Kleinhofs. 1996. Genetics of seedling and adult plant resistance to net blotch (Pyrenophora teres f. teres) and spot blotch (Cochliobolus sativus) in barley. Theor. Appl. Genet. 92:552-558.

5. Zhou, H., and B. Steffenson. 2013. Genome-wide association mapping reveals genetic architecture of durable spot blotch resistance in US barley breeding germplasm. Mol. Breeding 32:139-154.


A. Kleinhofs. 2015. Barley Genet. Newsl. 45:250.