BGS 481, Laxatum-j, lax-j

Laxatum-49 = lax-49 (6, 7).

Monofactorial recessive (5).
Located in chromosome 2H (2); lax-j.49 is associated with SNP markers 1_0399 to 2_0887 (positions 66.78 to 103.73 cM) in 2H bins 05 to 08 and a small segment of 3HL between markers 2_0944 and 1_1172 (positions 185.12 and 190.87 cM) in 3H bin 12 of the Bowman backcross-derived line BW465 (2).

Rachis internodes of lax-j.49 were about 24% longer than those of Bonus (7). Plants produced few tillers, awns were slightly twisted, seed set was reduced, and kernels were angular (7). Plants of the Bowman backcross-derived line for lax-j.49, BW465, headed eight days later than Bowman and had rachis internodes that were about 30% longer (6.0 vs. 4.6 mm). Compared to Bowman, BW465 plants were slightly shorter, had slightly shorter awns and peduncles, had slightly longer and wider leaf blades, and had about three more kernels per spike (5). Kernels were long (10.3 vs. 9.2 mm), thin (3.4 vs. 3.9 mm), and weighed less (5.1 vs. 6.0 mg). The caryopsis was partially exposed between the lemma and palea. Grain yields of BW465 were about 1/3 those of Bowman (5). A portion of the delayed heading of BW465 could be attributed to the late allele at the Early maturity 6 (Eam6) or Praematurum-c (mat-c) locus, which was retained in the 2H segment from the donor parent Bonus (1, 2).

An ethylene oxide induced mutant in Bonus (NGB 14657, PI 189763) (7, 9).

lax-j.29 (NGB 116364), -j 33 (NGB 116368), -j.49 (NGB 116383) in Bonus (NGB 14657, PI 189763) (3, 4, 7, 8).

lax-j.49 (NGB 116383) in Bonus; lax-j.49 in Bowman (PI 483237)*3 (BW465, NGB20695).

1. Comadran, J., B. Kilian, J. Russell, L. Ramsay, N. Stein, M. Ganal, P. Shaw, M. Bayer, W. Thomas, D. Marshall, P. Hedley, A. Tondelli, N. Pecchioni, E. Francia, V. Korzun, A. Walther, and R. Waugh. 2012. Natural variation in a homolog of Antirrhinum CENTRORADIALIS contributed to spring growth habit and environmental adaptation in cultivated barley. Nature Genet. 44:1388-1392.
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. Ehrenberg, L., Å. Gustafsson, and U. Lundqvist. 1959. The mutagenic effects of ionizing radiations and reactive ethylene derivatives in barley. Hereditas 45:351-368.
4. Ehrenberg, L., Å. Gustafsson, and U. Lundqvist. 1961. Viable mutants induced in barley by ionizing radiations and chemical mutagens. Hereditas 47:243-282.
5. Franckowiak, J.D. (Unpublished).
6. 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.
7. Larsson, H.E.B. 1985. Morphological analysis of laxatum barley mutants. Hereditas 103:239-253.
8. Larsson, H.E.B. 1985. Genetic analysis of laxatum barley mutants. Hereditas 103:255-267.
9. Lundqvist, U. (Unpublished).

H.E.B. Larsson and U. Lundqvist. 1986. Barley Genet. Newsl. 16:64.

U. Lundqvist and J.D. Franckowiak. 2017. Barley Genet. Newsl. 47:145-146.