A Database for Triticeae and Avena
II.43. Tight linkage of the awnless gene in Engleawnless with the
G. A. Wiebe. Collaborator, USDA, ARS, PSRD, Cereal Crops Research Branch,
Beltsville, Maryland 20705, U.S.A.
Englelawnless CI 3119 is an awnless 2-rowed barley from Iraq. It was
crossed with Manchuria CI 2330, a 6-rowed fully awned variety. The F1 is
awnless or nearly so with considerable seed set in the lateral flowers.
The F2 gave only three types; 2-row awnless, the F1 type, and 6-row awned
in a 1:2:1 ratio. Additional F2 populations gave similar results. Since
the heterozygote F1 type is easily identified, a large number of such plants
were saved. A large F2 population of approximately 200,000 plants were
grown over a 3-year period. Not a single 2-rowed awned or a 6-rowed awnless
plant was recovered. It is concluded these two genes are very tightly linked.
It would seem very unusual if the Vv locus controlled both row
type and awning, or conversely for the awning locus. The existence of a
short inversion covering the Vv and awning loci is suggested as
an explanation for these results. Crossing over as measured by recombinants
is drastically reduced within the inversion loop because of the formation
of duplications and deficiencies. Barley workers have long observed many
associated differences between 6-rowed and 2-rowed genotypes in their breeding
and research programs, and I found a similar pattern in my 20 pairs of
6-rowed vs 2-rowed isogenic lines. These observations support the notion
of an inversion at the Vv locus.
BGN 2 toc
BGN Main Index