BGS 617, Uniculme 4, cul4

Uniculme-5 = uc-5 (4).
Uniculme-3 = uc-3 (4).
Hordeum vulgare Uniculme 4 = HvCul4 (6).

Monofactorial recessive (4).
Located in chromosome 3HL (8); cul4.3 is near AFLP marker E4143-4 in subgroup 32 of the Proctor/Nudinka map (5); cul4.3, cul4.5, cul4.15, and cul4.16 mapped near RFLP markers CDO0394a and CDO105 (9); cul4.5 is associated with SNP markers 1_0646 to 2_0339 (positions 239.73 to 248.51 cM) in 3H bin 15 of the Bowman backcross-derived line BW212 (2); cul4.3 is associated with SNP markers 2_0136 to 1_0044 (positions 138.00 to 190.80) in 3H bins 08 to 13 and with markers 1_0646 to 2_1362 (positions 239.73 to 255.13 cM) in 3H bins 15 and 16 of the Bowman backcross-derived line BW211 (2), likely in 3HL bin 15.

Plants produce 1 to 4 tillers that are twisted and have slightly bowed culm internodes. All secondary tillers are shorter than the primary tiller and have a curly appearance. Often secondary tillers are trapped at the base of the primary tiller (3, 7). Compared to normal sibs, cul4 plants of the Bowman backcross-derived lines for cul4.3 (BW211) and cul4.5 (BW212) had peduncles that were 50% longer. Rachis internodes were slightly elongated, and kernels were slightly longer. Plant height varied from 2/3 normal to slightly taller than Bowman (3). The BW 212 line with cul4.15 mutant exhibited more variation in height over environments (3). Under greenhouse conditions, the Bowman backcross-derived line for cul4.5, BW212, developed only two axillary tillers, and it was uniculm when combined with the cul2.b (uniculm 2) gene (1). The cul4 mutants cause reduced tillering, deregulation of the number of axillary buds in an axil, and alterations in leaf proximal-distal patterning (10). Only one or two axils of BW212 plants contained axillary buds, but often two buds instead of one bud were present. These axillary buds were sometimes associated with the development of leafy shoots. All cul4 mutants had a liguleless phenotype (9). The Cul4 gene was isolated by positional cloning and shown to encode a BTB-ankyrin protein closely related to Arabidopsis BLADE-ON-PETIOLE1 (BOP1) and BOP2 (10). Morphological, histological and in situ RNA expression analyses indicated that the dominant allele at the Cul4 locus acts at axil and leaf boundary regions to control axillary bud differentiation, as well as development of the ligule (10). The Cul4 locus was confirmed to be a homolog of the Arabidopsis genes BLADE-ON-PETIOLE1 (BOP1) and BOP2 (6). The HvCul4 gene and its paralog HvLax-a are involved in primarily in regulating tiller number and spike morphology, respectively. Analysis of natural alleles at the Cul4 locus identified 31 haplotype variants (6).

An ethylene oxide induced mutant in Bonus (NGB 14657, PI 189763) (6). More information about the origins and nature of mutants at the cul4 locus is presented in www.nordgen.org/bgs and by Jost et al. (6).

cul4.3 (NGB 115062, GSHO 2495), cul4.5 (NGB 115063, GSHO 2493) in Bonus (NGB 14657, PI 189763), cul4.15 (NGB 115064) in Foma (NGB 14659, CIho 11333), cul4.16 (NGB 115065) in Bonus (7, 9); cul4.24 (NGB 119360) in Flare (NGB 1518) (7, 10, 11).

cul4.3 (NGB 115062, GSHO 2495) in Bonus; cul4.5 (NGB 115063, GSHO 2493) in Bonus; cul4.3 in Bowman (PI 483237)*3 (GSHO 2360); cul4.3 in Bowman*4 (BW211, NGB 22038); cul4.5 in Bowman*4 (GSHO 2361); cul4.5 in Bowman*7 (BW212, NGB 22039); cul4.15 in Bowman*3 (BW208, NGB 22036); cul4.16 in Bowman*2 (BW209, NGB 20559); cul4.24 in Bowman*3 (BW210, NGB 22037).

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. 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.

3. Franckowiak, J.D. (Unpublished).

4. Gustafsson, Å., A. Hagberg, U. Lundqvist, and G. Persson. 1969. A proposed system of symbols for the collection of barley mutants at Svalöv. Hereditas 62:409-414.

5. Hussien, A., E. Tavakol, D.S. Horner, M. Muñoz-Amatriaín, G.J. Muehlbauer, and L. Rossini. 2014. Genetics of tillering in rice and barley. The Plant Genome 7. 1-20.

6. Jost, M., S. Taketa, M. Mascher, A. Himmelbach, T. Yuo, F. Shahinnia, T. Rutten, A. Druka, T. Schmutzer, B. Steuernagel4, S. Beier, S. Taudien, U. Scholz, M. Morgante, R. Waugh, and N. Stein. 2016. A homolog of Blade-On-Petiole 1 and 2 (BOP1/2) controls internode length and homeotic changes of the barley inflorescence. Plant Physiol. 171:1113-1127.

7. Lundqvist, U. (Unpublished).

8. 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.

9. Rossini, L., A. Vecchietti, L. Nicoloso, N. Stein, S. Franzago, F. Salamini, and C. Pozzi. 2006. Candidate genes for barley mutants involved in plant architecture: An in silico approach. Theor. Appl. Genet. 112:1073-1085.

10. Tavakol, E., R. Okagaki, G. Verderio, V. Shariati J., A. Hussien, H. Bilgic, M.J. Scanlon, N. R. Todt, T.J. Close, A. Druka, R. Waugh, B. Steuernagel, R. Ariyadasa, A. Himmelbach, N. Stein, G.J. Muehlbauer, and L. Rossini. 2015. The barley Uniculme4 gene encodes a BLADE-ON-PETIOLE-like protein that controls tillering and leaf patterning. Plant Physiol. 168:164-174.

11. Tavakol, E., G. Verderio, T. Fusca, S. Ciannamea, T.J. Close, A. Druka, R. Waugh, M. Mihaela, K. Mayer, R. Ariyadasa, D. Schulte, R. Zhou, N. Stein, G.J. Muehlbauer, and L. Rossini. 2012. Positional cloning of the barley tillering gene uniculme 4. http://www.triticeaegenome.eu/file/Tavakol-Poster_Versailles_2012.pdf.

J.D. Franckowiak and U. Lundqvist. 2002. Barley Genet. Newsl. 32:118.

J.D. Franckowiak and U. Lundqvist. 2007. Barley Genet. Newsl. 37:289.
J.D. Franckowiak and U. Lundqvist. 2013. Barley Genet. Newsl. 43:162-163.
J.D. Franckowiak and U. Lundqvist. 2014. Barley Genet. Newsl. 44:192-193.
J.D. Franckowiak and U. Lundqvist. 2016. Barley Genet. Newsl. 46:132-133.