BGS 9, Dense spike 1, dsp1

Dense spike = l (19, 22).
Lax spike = L1 (9).
Short spike = e (21).
Dense spike-ar = dsp.ar (2, 15).

Monofactorial recessive (1, 6, 22).
Located in chromosome 7HS (7, 9); about 10.5 cM distal from the nud1 (naked caryopsis 1) locus (18, 19); dsp1.a is near molecular marker cMWG704 (11); dsp1.a is located near the centromere (11, 20); dsp1.a is near markers Bmag0359 and Bmag0321 (20); dsp.ar (dsp1.ar) is in a 0.37 cM interval between markers SC57808 (Hv_SPL14) and CAPSK06413 located in the short and long arm at the centromere of 7H (15); dsp1.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 (2); dsp1.ap, dsp1.aq, dsp1.ar, and dsp1.at have in common from their donor parent Volla SNP markers 1_0299 to 2_0485 (positions 101.23 to 121.90 cM) in 7H bin 07 of the Bowman backcross-derived lines BW263 to BW266 (2); dsp1.ae, dsp1.ag, dsp1.ah, and dsp1.af (formerly called Pyr.af) have Haisa-type of SNP marker patterns in the region from 1_0128 to 1_0169 (positions 97.66 to 142.55 cM) in 7H bins 07 to 08 of the Bowman backcross-derived lines BW255, BW256, BW257, and BW654 (2); dsp1.aa (formerly pyr.aa), dsp1.ac, dsp1.ay, and dsp1.az (BW652, BW254, BW271, and BW272, respectively) originated from different cultivars, but retained SNP marker in the centromeric region of 7H identical to those of the Haisa-type (2); dsp1.f (formerly Zeo.f) is associated with SNP markers 1_1098 to 1_0303 (positions 68.46 to 120.92 cM) in 7H bin 07 of the Bowman backcross-derived line BW935 (2); dsp1.a with nud1.a and fst3.c 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 (2), in 7H bin 07.

Spike length is reduced because rachis internode length is about 2/3 normal. The reduction in rachis internode length caused by the dsp1.a and uzu1.a (uzu 1) alleles is similar and additive (16, 19). In F2 progenies, the dsp1.a gene has pleiotropic effects on coleoptile length, culm length, and grain size (16). The original mutant line for dsp1.ah (Mut. 4841) was associated with increased grain yield (12), but the Bowman backcross-derived line with dsp1.ah (BW257) yielded less than half as much as Bowman (3). The rachis internode lengths of the Bowman backcross-derived lines from Volla mutants (BW263 to BW266) averaged 2.7 mm compared to 4.5 mm for Bowman. Plants were slightly shorter than Bowman, kernels were shorter 8.7 vs. 9.8 mm and slightly wider, and kernels weights were about 10% lower (5.2 vs. 5.7 mg) (3, 15). BW264, which contains only the 7H segment from Volla, appeared to have a lower reduction in plant height and kernel weights (3). The BW lines with the donor parents Haisa (BW255, BW654), Freya (BW256), and Saale (BW257) headed about two days later than Bowman and were about 20% shorter. Kernels were shorter and about 20% lighter. Awns of BW lines having Haisa-type as a donor were shorter, 9 vs. 11 cm, and grain yields were less than 50% of the Bowman yields. The Haisa line (BW654), retaining only a 7H region from the donor parent, was later and shorter than the other Haisa-type lines (3). The BW lines with a Volla mutant differed from the BW lines with a Haisa mutant by only one SNP marker, 1_1219 at 107.44 cM (3). Phenotypically, BW254 with dsp1.ac, BW271 with dsp1.ay, and BW272 with dsp.1.az were similar to the BW lines from Volla, while BW652 with dsp1.aa was similar to the BW lines from Haisa. Since BW lines from Haisa and Volla having other phenotypic variants have the same SNP marker heterogeneities in 7H lack the dense spike trait, the mutants named in this BGS description are likely independent mutants at the dsp1 locus (2, 3). BW935 with dsp1.f was morphological similar to the BW lines with the Haisa mutants. The internode lengths in BW375 with dsp1.a were similar to those of other presumed dsp1 mutants, but other morphological traits were affected by the presence of the fst3.c (fragile stem 3) gene (3).

Natural occurrence in cultivars from China, Japan, and Korea (22); X-ray induced mutants in Donaria and Haisa (13, 14); induced mutants in Haisa II (5).

dsp1.a in many cultivars of Oriental origin, often associated with the short awn gene (16); dsp1.f (formerly called Zeo.f) (18:15:4I, GSHO 2137) in Birgitta (NSGC 1870, NGB 14667, NGB 1494) (8); dsp1.aa (formerly pyr.aa) (Betzes Erectoides, CIho 10871, GSHO 2431) in Betzes (PI 129430) (10); dsp1.ac (Mut. 2654, GSHO 1716) in Donaria (PI 161974) (13); dsp1.ae (Mut. 4014, GSHO 1717), dsp1.af (formerly Pyr.af) (Mut. 4158, GSHO 1718) in Haisa (PI 197617) (13), dsp1.ag (Mut. 4551, GSHO 1719) in Freya (PI 290197) (14), dsp1.ah (Mut. 4841) in Saale (Piroline, PI 539132) (12); dsp1.ap (7112, GSHO 1724), dsp1.aq (7113, GSHO 1725), dsp1.ar (7114, GSHO 1726), dsp1.at (7117, GSHO 1727) in Volla (PI 280423) (4, 5); dsp1.ay (WA11005-81, GSHO 1729) in WA9037-75 (see PI 639908 for pedigree) (23); dsp1.az (Wa1628-85) in Hazen (PI 483238) (23).

dsp1.a in Honen 6 (OUJ469, PI 307495, GSHO 1232); dsp1.a in Bowman*7 (GSHO 1833, BW 277, NGB 20561); dsp1.aa (Betzes Erectoides, CIho 10871, GSHO 2431) in Betzes; dsp1.ar in Volla (GSHO 1726); dsp1.f in Bowman*7 (GSHO 2137, BW935, NGB 22364); dsp1.aa in Bowman*4 (GSHO 2236), in Bowman*6 (BW652, NGB 22217); dsp1.ac in Bowman*5 (GSHO 2237, BW254, NGB 22079); dsp1.ae in Bowman*4 (GSHO 2239), in Bowman*5 (BW255, NGB 22080); dsp1.af in Bowman*5 (GSHO 2142) in Bowman*6 (BW654, NGB 22219); dsp1.ag in Bowman*4 (GSHO 2240), in Bowman*5 (BW256, NGB 22081); dsp1.ah in Bowman*7 (BW257, NGB 22082); dsp1.ap in Bowman*4 GSHO 2245), in Bowman*5 (BW263, NGB 22088); dsp1.aq in Bowman*5 (GSHO 2246), in Bowman*6 (BW264, NGB 22089); dsp1.ar in Bowman*7 (GSHO 1942, BW265, NGB 22090); dsp1.at in Bowman*5 (GSHO 2247, BW267, NGB 22092); dsp1.ay in Bowman*3 (GSHO 2250, BW271, NGB 22096); dsp1.az in Bowman*5 (BW272, NGB 22097); dsp1.a with nud1.a and fst3.c from Kobinkatagi 4 (OUM 382, GSHO 1746) in Bowman*6 (GSHO 1842); dsp1.a with nud1.a and fst3.c in Bowman*7 (BW375, NGB 20614).

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