International Database for Barley Genes and Barley Genetic Stocks

BGS 472, Accordion basal rachis internode 1, abr1

BGN  26:419
Stock number: BGS 472
Locus name: Accordion basal rachis internode 1
Locus symbol: abr1

Previous nomenclature and gene symbolization:

Laxatum-3 = lax-3 (1, 2, 3).


Monofactorial recessive (2, 3).
Located in chromosome 2HL (5); abr1.a is about 7.4 cM proximal from the fch15 (chlorina seedling 15) locus (5); abr1.a is about 6.3 cM proximal from the Gth1 (Toothed lemma 1) locus (6).


Rachis internodes in the upper part of the spike are about 12% longer than normal. Secondary and tertiary shoots may form at the accordion-like basal rachis nodes (2, 5). Manifestation of the extra shoots may be a day-length response and genotype dependent. Heading is delayed in the Bowman backcross-derived line. Recombination with the eog1.a (elongated outer glume) allele has not been observed (5, 6), and recombination with the vrs1.a (six-rowed spike 1) allele is low (6).

Origin of mutant:

An X-ray induced mutant in Bonus (NGB 14657, PI 189763) (2).

Mutational events:

abr1.a (lax.3, NGB 116337, GSHO 1563), abr1.b (lax.12, NGB 116346) in Bonus (NGB 14657, PI 189763), abr1.c (lax.337, NGB 116556) in Foma (NGB 14659, CIho 11333) (2, 4).

Mutant used for description and seed stocks:

abr1.a (GSHO 1563, NGB 116337) in Bonus; abr1.a in Bowman (PI 483237)*7 (GSHO 1887, BW001, NGB 20409).


1. 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.

2. Larsson, H.E.B. 1981. Branching spike mutants from two loci in two-row barley. BGN 11:25-28.

3. Larsson, H.E.B. 1985. Morphological analysis of laxatum barley mutants. Hereditas 103:239-253.

4. Larsson, H.E.B. 1985. Genetic analysis of laxatum barley mutants. Hereditas 103:255-267.

5. Larsson, H.E.B. 1985. Linkage studies with genetic markers and some laxatum barley mutants. Hereditas 103:269-279.

6. Luna Villafaña, A. 1995. Mapping marker genes in chromosome 2 of barley. M.S. Thesis. North Dakota State Univ., Fargo.


H.E.B. Larsson and U. Lundqvist. 1986. Barley Genet. Newsl. 16:55.


J.D. Franckowiak and U. Lundqvist. 1997. Barley Genet. Newsl. 26:419.