BGS 156, Long basal rachis internode 2, lbi2

Long basal rachis internode 2 = lb2 (5).
Erectoides-i = ert-i (6, 7, 8).

Monofactorial recessive (4, 5).
Located in chromosome 4HS (1, 5, 8); lbi2.b is less than 12.8 cM proximal from the Kap1 (Hooded lemma 1) locus (5, 7); ert-i.27 is about 2.4 cM proximal from the Kap1 locus (6); lbi2.b is about 18.5 cM proximal from the glf1 (glossy leaf 1) locus (9); lbi2.b is associated with SNP marker 1_1180 (position 58.13 cM) in 4H bin 05 of the Bowman backcross-derived line BW472 (1); ert-i.27 is associated with SNP markers 2_1374 to 2_1122 (positions 41.13 to 47.80 cM) in 4H bins 04 to 05 of the Bowman backcross-derived line BW311 (1), likely in 4H bin 05.

Mutant plants in the cultivar Montcalm have a marked elongation and weakness of the basal rachis internode of the spike. This region may be 10 to 13 cm long in some tillers. The spike hangs vertically downward from the collar on emergence from the sheath and is often broken off in this region by the wind. Even when not broken off, spikes have a high degree of sterility and contain poorly filled grain. Plants show delayed maturity (5). The ert-i mutants in Bonus have an erect, semi-compact (rachis internode length ranging from 2.3 to 2.9 mm) spike, an elongated (2 to 4 cm) basal rachis internode, and reduced plant height (3/4 normal) (8). Removal of modifiers from the Bonus and Montcalm mutants by backcrossing produced Bowman backcross-derived lines for ert-i.27, BW311, and lbi2.b, BW472, which had similar phenotypes (2, 3). Plants of the BW311 and BW472 lines were 15 to 20% shorter, had awns that were 30 to 40% shorter, and had shorter rachis internodes, 3.3 vs 4.5 mm. The number of kernels per spike was 4 to 6 fewer. Kernels of BW311 and BW472 were smaller and weighed less, 45 vs. 58 mg, than those of Bowman. Grain yields of BW311 and BW472 were 1/2 to 3/4 of those for Bowman (3).

A gamma-ray induced mutant in Montcalm (CIho 7149) (5).

lbi2.b (Alb Acc 1028, GSHO 572) in Montcalm (CIho 7149) (5); ert-i.27 (NGB 112627, GSHO 482), -i.53 (NGB 112652) in Bonus (NGB14657, PI 189763) (3, 4); ert-i.126 (NGB 112725) in Bonus (8).

lbi2.b (GSHO 572) in Montcalm; ert-i.27 (NGB 112627, GSHO 482) in Bonus; lbi2.b in Bowman (PI 483237)*7 (GSHO 2009, BW472, NGB 20702); ert-i.27 in Bowman*7 (GSHO 2008, BW311, NGB 22107).

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. 1992. Allelism tests among selected semidwarf barleys. Barley Genet. Newsl. 21:17-23.
4. 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.
5. Kasha, K.J., and G.W.R. Walker. 1960. Several recent barley mutants and their linkages. Can. J. Genet. Cytol. 2:397-415.
6. Persson, G. 1969. An attempt to find suitable genetic markers for the dense ear loci in barley I. Hereditas 62:25-96.
7. Persson, G. 1969. An attempt to find suitable genetic markers for the dense ear loci in barley II. Hereditas 63:1-28.
8. Persson, G., and A. Hagberg. 1969. Induced variation in a quantitative character in barley. Morphology and cytogenetics of erectoides mutants. Hereditas 61:115-178.
9. Schondelmaier, J., G. Fischbeck, and A. Jahoor. 1993. Linkage studies between morphological and RFLP markers in the barley genome. Barley Genet. Newsl. 22:57-62.

T.E. Haus and T. Tsuchiya. 1971. Barley Genet. Newsl. 1:142.

J.D. Franckowiak and U. Lundqvist. 1997. Barley Genet. Newsl. 26:183.
J.D. Franckowiak and U. Lundqvist. 2014. Barley Genet. Newsl. 44:93-94.