BGS 314, Six-rowed spike 2, vrs2

Six-rowed spike 2 = v2 (10).
Intermedium-b = int-b (6, 7, 13).

Monofactorial recessive (4, 5, 6, 8, 12).
Located in chromosome 5HL (10, 11); vrs2.e is over 19.0 cM proximal from the srh1 (short rachilla hair 1) locus (10 11, 12); vrs2.e is associated with SNP markers 2_1421 to 1_0477 (positions 159.51 to 173.49 cM) in 5H bins 09 to 10 of the Bowman backcross-derived line BW901 (1); int-b.3 is near the raw1 (smooth awn 1) locus based on linkage drag (3); int-b.3 is associated with SNP markers 2_0134 to 2_1355 (positions 163.29 to 234.98 cM) in 5H bins 10 to 13 of the Bowman backcross-derived line BW420 (1), likely in 5H bin 10. A high-resolution genetic map of the vrs2 locus was developed using recombinants and barley BACs (13).

The spike appears similar to the ordinary six-rowed spike, but the lateral spikelets on the upper and lower portion of the spike are reduced in size, less fertile, and more or less pedicellated. Lateral spikelets are pointed with reduced awn length or awnless (4, 11, 12). Kernels of the Bowman backcross-derived line for vrs2.e, BW901, were 15 to 20% lighter than kernels of Bowman. BW901 plants exhibited reduced tillering and grain yield was about half that of Bowman (2). Plants of the backcross-derived line for int-b.3, BW420, headed 2 to 3 days earlier than Bowman, but more lodging was observed. The BW420 kernels were slightly longer, but weighed less, 52 vs. 58 mg, compared to those of Bowman. Grain yields of BW420 were 10 to 30% of those recorded for Bowman (3). Late heading and prolonged development of BW901 was reported in Germany (13), but this was not observed in field tests in Australia, England, New Zealand, or the USA (3). During barley inflorescence and shoot development, the gene at the Vrs2 locus encodes for a SHORT INTERNODES (SHI) transcriptional regulator (13).

vrs2.e is an X-ray induced mutant in Svanhals (PI 5474, GSHO 784, OUU032) (10. 12). int-b.3 is a neutron induced mutant in Bonus (NGB 14657, PI 189763) (9).

vrs2.e (Kmut 27, OUM284, GSHO 773) in Svanhals (PI 5474, GSHO 784, OUU032) (12).; int-b.3 (NGB 115421, GSHO 1764), -b.6 (NGB 115424) in Bonus (NGB 14657, PI 189763) (6, 8); int-b.75 (NGB 115493) in Bonus (8); HOR19366 in the Genebank of the Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany. (isolated as spontaneous mutant in a cultivated landrace collection from USA) (13).

vrs2.e (Knut 27, GSHO 773, OUM284) in Svanhals; vrs2.e in Bowman (PI 483237)*4 (GSHO 2111); vrs2.e in Bowman*6 (BW901, NGB 22333); int-b.3 (NGB 115421, GSHO 1764) in Bonus; int-b.3 in Bowman (PI 483237)*6 (GSHO 2129); int-b.3 in Bowman*7 (BW420, NGB 20653).

1. 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.
2 Franckowiak, J.D. (Unpublished).
3. Franckowiak, J.D. 1995. Notes on linkage drag in Bowman backcross derived lines of spring barley. Barley Genet. Newsl. 24:63-70.
4. Fukuyama, T., J. Hayashi, I. Moriya, and R. Takahashi. 1972. A test for allelism of 32 induced six-rowed mutants. Barley Genet. Newsl. 2:25-27.
5. Fukuyama, T., R. Takahashi, and J. Hayashi. 1982. Genetic studies on the induced six-rowed mutants in barley. Ber. Ohara Inst. landw. Biol., Okayama Univ. 18:99-113.
6. Gustafsson, Å., and U. Lundqvist. 1980. Hexastichon and intermedium mutants in barley. Hereditas 92:229-236.
7. 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.
8. Lundqvist, U. (Unpublished).
9. Lundqvist, U., and A. Lundqvist. 1988. Induced intermedium mutants in barley: origin, morphology and inheritance. Hereditas 108:13-26.
10. Takahashi, R., J. Hayashi, and C. Hirao. 1968. Linkage studies. Barley Newsl. 11:59.
11. Takahashi, R., J. Hayashi, and I. Moriya. 1971. Linkage studies in barley. Barley Genet. Newsl. 1:51-58.
12. Takahashi, R., J. Hayashi, T. Konishi, and I. Moriya. 1972. Inheritance and linkage studies in barley. V. Locating of seven new mutant genes. Ber. Ohara Inst. landw. Biol., Okayama Univ. 15:147-168.
13. Youssef, H.M., K. Eggert, R. Koppolu, A.M. Alqudah, N. Poursarebani, A. Fazeli, S. Sakuma, A. Tagiri, T. Rutten, G. Govind, U. Lundqvist, A. Graner, T Komatsuda, N. Sreenivasulu, and T. Schnurbusch. 2017. VRS2 regulates hormone-mediated inflorescence patterning in barley. Nat. Genet. 49:157-161.

T. Fukuyama. 1983. Barley Genet. Newsl. 13:112.

U. Lundqvist and J.D. Franckowiak. 1997. Barley Genet. Newsl. 26:263.
U. Lundqvist and J.D. Franckowiak. 2017. Barley Genet. Newsl. 47:113-114.