BGS 631, Brachytic 3, brh3

The brh3 mutants are alleles at the ert-t (Erectoides-t) or BRASSINOSTEROID-6-OXIDASE (HvBRD) locus, which encodes a barley brassinosteroid-6-oxidase (2). See BGS 566 for more information on the alleles at the ert-t or HvBRD locus.

Brachytic-g = brh.g (4).
Brachytic-h = brh.h (1, 4).
Brachytic-i = brh.i (1, 4).
Brachytic-y = brh.y (1, 4).
Erectoides-t.55 = ert-t.55 (1, 8, 10).
Brachytic 4 = br4 (11).

Monofactorial recessive (4, 6).
Located in chromosome 2HS (1, 3); brh3.g is approximately 11.4 cM distal from SSR marker Bmac0134 (1), near the boundary between 2H bins 01 and 02 (1); brh3.g is associated with markers 2_0609 to 1_1059 (positions unmapped to 17.96) in 2H bin 02 of the Bowman backcross-derived line BW091 (3); brh3.y is associated with markers 1_0326 to 1_0180 (positions 16.91 to 40.06) in 2H bins 02 to 04 of the Bowman backcross-derived line BW094 (3); no SNP markers different from those of Bowman were retained in 2HS Bowman backcross-derived line for brh3.i, BW093 (3); the brh3 mutants are in the HvBRD locus, which encodes for a brassinosteroid-6-oxidase, and is located in the telomeric region of 2HS (2); in 2H bin 02.

The seedling leaf of brh3 plants is shorter than that of normal sibs. Plants are 2/3 to 3/4 of normal height and the number of tillers per plant is reduced. Awns are fine with slightly curly tips and are about 1/2 normal length. Spikes of brh3 plants have a slightly elongated first rachis internode. Seed set may be reduced when plants are grown under greenhouse conditions. (5). Spikes are semi-compact, rachis internode length is about 2.7 mm in the original mutant, and culm length is about 2/3 of normal. These phenotypic traits, included the dense spike and short awn, are inherited together (1, 5). Based on general appearance of the plants, the ert-t.55 mutant can be placed in the brachytic class of semidwarf mutants (1, 11). The brh3 mutants exhibited the brassinosteroid-deficient phenotype: shorter rachis internode length, short awns, acute leaf angles, slightly undulating basal leaf blade margins, and a slightly elongated basal rachis internode (2). The Bowman backcross-derived lines for brh3.g and brh3.y, BW091 and BW094, had kernels that were shorter, 8.7 vs 9.7 mm, and lighter, 4.6 vs 5.6 mg, than those of Bowman. Grain yields of BW091 and BW094 varied from 1/3 to 2/3 those of Bowman (5).

Probably a sodium azide induced mutant in Birgitta (NGB 14667, NGB 1494, NSGC 1870) (9).

brh3.g (GSHO 1672, 17:10:1, DWS1002) in Birgitta (NGB 14667, NGB 1494, NSGC 1870) (1, 4, 6); brh3.h (GSHO 1673, 17:11:3, DWS1003) in Birgitta; brh3.i (GSHO 1674, 17:12:1, DWS1004) in Birgitta (4, 6, 9); brh3.y (GSHO 1688, 10001, DWS1230) in Bido (PI 399485) (1, 4, 7). The brh3.g and brh3.h lines may be the same mutational event as a seed mixture was observed in the original seed lots (5) and both stocks have the same nonsense mutation in the ert-t (HvBRD) coding region (2).

brh3.g (GSHO 1672) in Birgitta; brh3.g in Bowman (PI 483237)*7 (GSHO 2167); ); brh3.g in Bowman (PI 483237)*7 (GSHO 2167, BW091, NGB 20497); brh3.h in Bowman*2 (GSHO 2168, BW092, NGB 20498); brh3.i in Bowman*6 (GSHO 2169); brh3.i in Bowman *7 (BW093, NGB 20499); brh3.y from Bido in Bowman*5 (GSHO 2178); brh3.y in Bowman*6 (BW094, NGB 20500). See BGS 566 for information about additional mutants at this locus.

1. Dahleen, L.S., L.J. Vander Wal, and J.D. Franckowiak. 2005. Characterization and molecular mapping of genes determining semidwarfism in barley. J. Hered. 96:654-662.

2. Dockter, C., D. Gruszka, I, Braumann, A. Druka, I. Druka, J. Franckowiak, S.P. Gough, A. Janeczko, M. Kurowska, J. Lundqvist, U. Lundqvist, M. Marzec, I. Matyszczak, A.H. Müller, J. Oklestkova, B. Schulz, S, Zakhrabekova, and M. Hanson. 2014. Induced variations in brassinosteroid genes define barley height and sturdiness, and expand the green revolution genetic toolkit. Plant Physiol. 166:1912-1927.

3. Druka, A., J. Franckowiak, U. Lundqvist, N. Bonar, J. Alexander, K. Houston, S. Radovic, F. Shahinnia, V. Vendrarnin, M. Morgante, N. Stein, and R. Waugh. 2011. Genetic dissection of barley morphology and development. Plant Physiol. 155:617-627.

4. Franckowiak, J.D. 1995. The brachytic class of semidwarf mutants in barley. Barley Genet. Newsl. 24:56-59.

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

6. Franckowiak, J.D., and A. Pecio. 1992. Coordinator’s report: Semidwarf genes. A listing of genetic stocks. Barley Genet. Newsl. 21:116-127.

7. Gaul, H. 1986. (Personal communications). 8. Hagberg, A., Å. Gustafsson, and L. Ehrenberg. 1958. Sparsely contra densely ionizing radiations and the origin of erectoid mutants in barley. Hereditas 44:523-530.

9. Lehmann, L. 1985. (Personal communications).

10. Persson, G., and A. Hagberg. 1969. Induced variation in a quantitative character in barley. Morphology and cytogenetics of erectoides mutants. Hereditas 61:115-178.

11. Tsuchiya, T. 1976. Allelism testing of genes between brachytic and erectoides mutants. Barley Genet. Newsl. 6:79-81.

J.D. Franckowiak. 2002. Barley Genet. Newsl. 32:134.
J.D. Franckowiak and U. Lundqvist 2015. Barley Genet. Newsl. 45:229-230.