International Database for Barley Genes and Barley Genetic Stocks

BGS 253, Uniculm 2, cul2

BGN  43:112
Stock number: BGS 253
Locus name: Uniculm 2
Locus symbol: cul2

Previous nomenclature and gene symbolization:

Uniculm 2 = uc2 (13).


Monofactorial recessive (13).
Located in chromosome 6HL (6, 8); about 1.3 cM distal from the gsh4 (glossy sheath 4) locus (4, 7); about 11.4 cM from the msg36 (male sterile genetic 36) locus (4, 7); about 2.2 cM proximal from the rob1 (orange lemma 1) locus (4, 6, 7); about 8.8 cM from RFLP markers cMWG679 and ABG458 and between rob1 and RFLP marker KFP128 (1); about 6.2 cM from AFLP marker E4343-10 in subgroup 54 of the Proctor/Nudinka map (12); cul2.l is located between SSR markers GBM1212 and Bmag 0613 (10); cul2.b is associated with SNP markers 2_0291 to 1_0469 (positions 81.35 to 119.40 cM) in 6H bins 06 to 08 of the Bowman backcross-derived line BW205 (3); cul2.b is associated with SNP markers 2_0675 to 1_1246 (positions 82,43 to 135.62 cM) in 6H bins 06 to 08 of the Bowman backcross-derived line BW206 (3); since BW205 and BW206 originated as the same mutant, the cul2 locus is likely located in 6H bin 06 because the same SNP markers are retained in both stocks, 2_1339 to 2_1310 (96.12 to 98.16 cM).


The cul2 plants have a single elongated culm (stem), the culm is usually straight and has a much greater diameter than normal, and plants are usually head earlier than normal (13). Kernels of the backcross-derived line for cul2.b, BW205, were longer and wider than Bowman kernels and weighed on average slightly more (5). The cul2.b plants initiate vegetative axillary meristems, but tillers fail to develop (1). Irregular placement of some spikelets and partial female sterility of lateral spikelets occur in the original stock (7) and in the Bowman backcross-derived line (1). Yield of uniculm plants is not restored when grown under high plant populations (2). Double mutant combinations with most other mutants that affect tiller number resulted in a uniculm vegetative phenotype (1). Stress response genes are up regulated in cul2.b mutants (11).

Origin of mutant:

A thermal neutron induced mutant in Kindred (CIho 6969) (13).

Mutational events:

cul2.b (GBC379, CIho 115530, GSHO 531) in Kindred (CIho 6969) (7), cul2.k (unck) in an unknown cultivar from the Max-Planck-Institut für Züchtungsforschung (12); cul2.l (FN237, GSHO 3648) in Steptoe (CIho 15229) (9).

Mutant used for description and seed stocks:

cul2.b (CIho 115530, GSHO 531) in Kindred; cul2.b in Bowman (PI 483237)*4 (GSHO 2074); cul2.b in Bowman*7 (BW205, NGB 22033); cul2.b plus rob1.a from sel 79Cal in Bowman*8 (GSHO 2075, BW206, NGB 22034).


1. Babb, S., and G.J. Muehlbauer. 2003. Genetic and morphological characterization of the barley uniculm2 (cul2) mutant. Theor. Appl. Genet. 106:846-857.
2. Dofing, S.M. 1996. Near-isogenic analysis of uniculm and conventional-tillering barley lines. p. 617-619. In A.E. Slinkard, G.J. Scoles, and B.G. Rossnagel (eds.) Proc. Fifth Int. Oat Conf. & Seventh Int. Barley Genet. Symp., Saskatoon. Univ. of Saskatchewan, Saskatoon.
3. Druka, A., J. Franckowiak, U. Lundqvist, N. Bonar, J. Alexander, K. Houston, S. Radovic, F. Shahinnia, V. Vendramin, M. Morgante, N. Stein, and R. Waugh. 2011. Genetic dissection of barley morphology and development. Plant Physiol. 155:617-627.
4. Falk, D.E., M.J. Swartz, and K.J. Kasha. 1980. Linkage data with genes near the centromere of barley chromosome 6. Barley Genet. Newsl. 10:13-16.
5. Franckowiak, J.D. (Unpublished).
6. Hayashi, J., T. Konishi, I. Moriya, and R. Takahashi. 1984. Inheritance and linkage studies in barley. VI. Ten mutant genes located on chromosomes 1 to 7, except 3. Ber. Ohara Inst. landw. Biol., Okayama Univ. 18:227-250.
7. Kasha, K.G., D.E. Falk, and A. Ho-Tsai. 1978. Linkage data with genes on chromosome 6. Barley Genet. Newsl. 8:61-65.
8. Kirby, E.J. 1973. Effect of temperature on ear abnormalities in uniculm barley. J. Exp. Bot. 24:935-947.
9. Kleinhofs, A., and G.J. Muehlbauer (Unpublished).
10. Liu, Y.X., X.-H. Sun, B.-L. Xu, and G.-Y. Chen. 2012. Genetic analysis and molecular mapping of low-tillering mutants (cul2.b and lnt1.a) in barley (Hordeum vulgare L.). J. Plant Sci. 7:105-112.
11. Okagaki, R.J., S. Cho, W.M. Kruger, W.W. Xu, S. Heinen, and G.J. Muehlbauer. 2013. The barley UNICULM2 gene resides in a centromeric region and may be associated with signaling and stress response. Funct. Integr. Genomics 13:33-41.
12. Pozzi, C., D. di Pietro, G. Halas, C. Roig, and F. Salamini. 2003. Integration of a barley (Hordeum vulgare) molecular linkage map with the position of genetic loci hosting 29 developmental mutants. Heredity 90:390-396.
13. Shands, R.G. 1963. Inheritance and linkage of orange lemma and uniculm characters. Barley Newsl. 6:35-36.


C.R. Burnham. 1971. Barley Genet. Newsl. 1:156.


J.D. Franckowiak. 1997. Barley Genet. Newsl. 26:234.
J.D. Franckowiak. 2007. Barley Genet. Newsl. 37:253-254.
J.D. Franckowiak. 2013. Barley Genet. Newsl. 43:112-113.