BGS 12, Desynapsis 1, des1

Long chromosome = lc (1, 6, 8).

Monofactorial recessive (1, 6).
Located in chromosome 7H (1, 6); des1.a is associated with SNP markers 2_1491 to 2_0495 (positions 64.19 to 121.90 cM) in 7H bins 05 to 07 of the Bowman backcross-derived line BW228 (2); des1.v is associated with SNP markers 2_0126 to 1_0056 (positions 49.45 to 51.93) in 7H bin 04 of the Bowman backcross-derived line BW229 (2), likely in 7H bin 05.

The name long chromosome refers to the frequent occurrence of rod bivalents at metaphase I (3). The chromosomes are paired during pachytene, but undergo desynapsis during diplotene. The degree of desynapsis is d = 2.6 ± 1.6 ranged from 7 ring bivalents (d = 0) to 5 rod bivalents plus 4 univalents (d = 9). Lagging chromosomes and micronuclei were observed frequently at telophase I. Microspore tetrads contained an average of 0.3 micronuclei per tetrad with a range of 0 to 6. Ovule fertility was about 45% (4). Seed set on BW229, the Bowman backcross-derived line with the des1.v mutant, was variable with grain yields ranging from very little to 40% of the Bowman yields. BW229 plants headed 2 to 3 days later than Bowman and had about 4 more developed spikelets per spike. Kernels of BW229 weighed 5 to 10% more than Bowman kernels (3).

An X-ray induced mutant in Mars (CIho 7015) (3, 6).

des1.a (GSHO 592) in Mars (CIho 7015) (1, 6, 7); des1.v in Freja (CIho 7130) (5, 7).

des1.a (GSHO 592) in Mars; des1.a in Bowman*2 (BW228, NGB 22055); des1.v in Bowman*6 (BW229, NGB 22056).

1. Burnham, C.R. 1946. A gene for "long" chromosome in barley. Genetics 31:212-213. (Abstr.)
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 Franckowiak, J.D. (Unpublished).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. Hernandez-Soriano, J.M. 1973. Desynaptic mutants in Betzes barley. M.S. Thesis. Univ. of Arizona, Tucson.
5. Hernandez-Soriano, J.M., and R.T. Ramage. 1973. Coordinator's report. Desynaptic genes. Barley Genet. Newsl. 3:91.
6. McLennan, H.A. 1947. Cytogenetic studies of a strain of barley with long chromosomes. M.S. Thesis. Univ. of Minnesota, St. Paul.
7. Ramage, R.T., and J.M. Hernandez-Soriano. 1972. Desynaptic genes in barley. Barley Genet. Newsl. 2:65-68.
8. Robertson, D.W., G.A. Wiebe, and R.G. Shands. 1947. A summary of linkage studies in barley: Supplement I, 1940-1946. J. Am. Soc. Agron. 39:464-473.

J.M. Hernandez-Soriano, R.T. Ramage, and R.F. Eslick. 1973. Barley Genet. Newsl. 3:124.

J.D. Franckowiak. 1997. Barley Genet. Newsl. 26:57.
J.D. Franckowiak. 2012. Barley Genet. Newsl. 42:58-59.