BGS 24, Fragile stem 3, fst3

Fragile stem 3 = fs3 (5).

Monofactorial recessive (5).
Located in chromosome 7HS (1, 5); fst3.c is probably proximal from the dsp1 (dense spike 1) locus based on linkage drag (4); fst3.c with dsp1.a and nud1.a is associated with SNP markers 2_0671 to 2_0485 (positions 93.97 to 121.90 cM) in 7H bins 06 to 07 of the Bowman backcross-derived line BW375 (1), in 7H bin 07.

The leaf and stem characteristics of fst3 plants are similar to those of fst1 plants. Leaves and stems are very fragile and easily broken when slightly bent (5). Plants are about 2/3 normal height when protected in the greenhouse, but in the field plants are weak and are easily damaged by wind. The dense spike 1 (dsp1.a) and the naked caryopsis 1 (nud1.a) genes are also present with the fst3.c gene in Bowman backcross-derived line BW375 (3). BW375 plants were about half the height of Bowman, heading was delayed 3 to 10 days, kernels weight were 30 to 40% lower, and grain yields were from 0 to 30% of those for Bowman (3). In the OUM382 mutant line, crystalline cellulose content was reduced by 25% to 50% compared with the OUJ066 wild-type line (1, 6, 7, 8), and these reductions were similar to those observed in the fst2 mutant lines (1, 8). The number of cellulose synthesizing terminal complexes was reduced by 80% in the fst3.c mutant (6).

A spontaneous mutant in Kobinkatagi 4 (OUJ066, PI 190757) (5).

fst3.c (OUM382, GSHO 1746) in Kobinkatagi 4 (OUJ066, PI 190757) (5).

fst3.c (GSHO 1746, OUM382) in Kobinkatagi 4; fst3.c with nud1.a and dsp1.a in Bowman (PI 483237)*5 (GSHO 1842); fst3.c with nud1.a and dsp1.a in Bowman*7 (BW375, NGB 20614).

1. Burton, R.A., G. Ma, U. Baumann, A.J. Harvey, N.J. Shirley, J. Taylor, F. Pettolino, A. Bacic, M. Beatty, C.R. Simmons, K.S. Dhugga, J.A. Rafalski, S.V. Tingey, and G.B. Fincher. 2010. A customized gene expression microarray reveals that the brittle stem phenotype fs2 of barley is attributable to a retroelement in the HvCesA4 Cellulose Synthase Gene 1. Plant Physiol. 153:1716-1728.
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 Franckowiak, J.D. (Unpublished).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. Franckowiak, J.D. 1995. Notes on linkage drag in Bowman backcross derived lines of spring barley. Barley Genet. Newsl. 24:63-70.
5. Hayashi, J., and I. Moriya. 1985. Trisomic analysis of a fragile stem mutant found in Kobinkatagi 4. Barley Genet. Newsl. 15:47-48.
6. Kimura, S., N. Sakurai, and T. Itoh. 1999. Different distribution of cellulose synthesizing complexes in brittle and non-brittle strains of barley. Plant Cell Physiol. 40:335-338.
7. Kokubo, A., S. Kuraishi, and N. Sakurai. 1989. Culm strength of barley: correlation among maximum bending stress, cell wall dimensions, and cellulose content. Plant Physiol. 91:876-882.
8. Kokubo, A., N. Sakurai, S. Kuraishi, K. Takeda. 1991. Culm brittleness of barley (Hordeum vulgare L.) mutants is caused by smaller number of cellulose molecules in cell wall. Plant Physiol. 97:509-514.

T. Konishi and J.D. Franckowiak. 1997. Barley Genet. Newsl. 26:70.

J.D. Franckowiak. 2011. Barley Genet. Newsl. 41:74-75.