BGS 340, Smooth awn 2, raw2

Smooth awn 2 = r1 (4).
Smooth awn 2 = r2 (1).

Monofactorial recessive (1), segregation ratios obtained from studies of rough vs smooth awn may be distorted because the raw2 locus is linked to the raw1 (smooth awn 1) locus (2).
Located in chromosome 5HL (1); raw2.b is about 26.0 cM (probably distal) from the raw1 (smooth awn 1) locus (1).

The number of barbs present on the awn is reduced by the recessive allele at the raw2 locus (1, 3). When the recessive allele is present at only the raw2 locus, awns are intermediate or semi-rough (3). When recessive alleles occur at both the raw2 and raw1 loci, awns are very smooth or devoid of barbs. The existence of two or more genes controlling barbing of awns in Lion is reported in several studies (4, 5, 7).

Natural occurrence in Lion (CIho 923) and probably spring two-rowed cultivars from Europe with a semi-rough awn.

raw2.b in Lion as observed in Mich 832-188 (1, 6).

raw2.b in Lion (GSHO 27).

1. Atkins, R.E., and K.J. Frey. 1957. Inheritance of awn barbing in two barley crosses. Agron J. 49:558-560.
2. Franckowiak, J.D. 1991. Association of male sterility genes with a specific chromosome using multiple marker stocks. Barley Genet. Newsl. 20:31-36.
3. Friesen, H.A. 1946. Awn-barbing in barley. Canad. Jour. Res. C. 24:292-297.
4. Griffee, F. 1925. Correlated inheritance of botanical characters in barley and manner of reaction to Helminthosporium sativum. J. Agric. Res. 30:915-935.
5. Robertson, D.W., G.W. Deming, and D. Koonce. 1932. Inheritance in barley. J. Agric. Res. 44:445-466.
6. Robertson, D.W., G.A. Wiebe, R.G. Shands, and A. Hagberg. 1965. A summary of linkage studies in cultivated barley, Hordeum species: Supplement III, 1954-1963. Crop Sci. 5:33-43.
7. Sigfusson, S.J. 1929. Correlated inheritance of glume color, barbing of awns and length of rachilla hairs in barley. Sci. Agric. 9:662-674.

J.D. Franckowiak. 1997. Barley Genet. Newsl. 26:289.