Plant Sciences Department
University of Arizona
Tucson, Arizona 85721, U.S.A. "R"
Following the advice of Eslick and Hockett (1967) "that a certain amount of allelism testing might help clarify some of the barley genetic literature, we are reporting the results of allelism tests involving the loci lk2 on chromosome 1 and lk5 on chromosome 4.
The lk2 locus is on chromosome 1 and a number of alleles have been reported at the locus (Eslick and Hockett, 1967). The official gene description (BGN 3: 119) describes the lk2 mutant as monofactoral and recessive to the long-awned condition with the awns reduced to about 3/5th of the long-awned type.
An incompletely dominant mutant for short awn that was induced in the variety "Morex", C. 1. 15773, was described by Ramage (1984). The mutant was assigned to chromosome 1 based on linkage with msg1O (Ramage and Eckhoff, 1985). Tsuchiya (1962) reported an incompletely dominant mutant for short awn (KM-200) in which the heterozygote has medium length awns. Tsuchiya and Singh (1972) and Tsuchiya and Hall (1978), based on trisomic analysis, suggested that the locus was on Telo 1L.
We crossed the mutant in "Morex" with the mutant KM-200 and with the variety "Washonupana" which has the lk2 allele derived from "Sermo," C. I. 7776 (Eslick and Hockett, 1967). The F1 of the Morex mutant and Washonupana had an awn length similar to Washonupana, longer than the Morex mutant and about the length of the F1 between the Morex mutant and normal long-awned Morex The F1 of the Morex mutant and the KMI-200 mutant was a little longer than either the Morex or KM-200 mutant but was a little shorter than the heterozygote in Morex.
Although there may be other explanations for the observations, it appears that the mutants in Morex and KM-200 are alleles at the lk2 locus. Eslick and Hockett (1967) reported that "Half-awned Atlas", C. 1. 10963, carries an allele at the lk2 locus. Apparently, the lk2 locus has several alleles that differ in expression and dominance relationships. We are growing F3 progenies to confirm allelism and dominance relationships.
A recessive short-awned mutant was also induced in the variety Morex and Ramage and Eckhoff (1985) reported that it appeared to be linked with msg24 on chromosome 4. Earlier, a recessive short awn mutant, designated lk,,f, that had been inducted in a two-row, backcrossed derived form of the variety "Glacier", was reported to be linked with msg24 on chromosome 4 (Eckhoff and Ramage, 1984). Litzenberger and Green (1951) reported that a short-awned mutant, now designated lk5 (BGN 10: 119), was linked with the hooded locus on chromosome 4. Tsuchiya (1974) found that two other short awn mutants, ari-c and KM-218, were allelic to lk5.
We crossed the short-awned Morex mutant with lk5 in KT4-218 and with lk,,f and we also crossed lk5 with Ik,,f. All three F1s had short awns of about the same length which was about the same length as the three parents. This indicates that the three mutants, short-awned Morex, lk,,f and lk5, are alleles at the same locus on chromosome 4. We are growing F3 progenies to confirm the suspected allelic relationships.
Eckhoff, J. L. A. and R. T. Ramage. 1984. Assignment of a short awn mutant to chromosome 4. Barley Genetics Newsletter 14: 20-21.
Eslick, R. F. and E. A. Hockett. 1967. Allelism for awn length, lk2, in barley (Hordeum species). Crop Science 7: 266-267.
Litzenberger, S. C. and J. M. Green. 1951. Inheritance of awns in barley. Agron. Journal 43: 117-123.
Ramage, R. T. 1984. A semidominant short awn mutant in Morex. Barley Genetics Newsletter 14: 19-20.
Ramage, R. T. and J. L. A. Eckhoff. 1985. Assignment of mutants in Morex to chromosomes. Barley Genetics Newsletter 15: 22-23.
Tsuchiya, T. 1962. Radiation breeding in two-rowed barley. Seiken Ziho 14: 21-34.
Tsuchiya, T. 1974. Allelic relationships of genes for short-awned mutants. Barley Genetics Newsletter 4: 80-81.
Tsuchiya, T. and L. B. Hall. 1978. Telotrisomic analysis of four mutant genes in barley. Barley Genetics Newsletter 8: 104-107.
Tsuchiya, T. and R. J. Singh. 1972. Trisomic analysis of a short awn mutant in barley. Barley Genetics Newsletter 2: 99.