GrainGenes
A Database for Triticeae and Avena
Eckhoff & Ramage, pp. 20-21
II.11. Assignment of a short awn mutant to chromosome 4.
J. L. A. Eckhoff, University of Arizona, and, R. T. Ramage, Agricultural Research Service, U. S. Department of Agriculture and University of Arizona, Tucson, Arizona 85721, U.S.A. "R"
A number of mutants were induced in a two-row, backcrossed, derived, form of the cultivar 'Glacier'. Several of the mutants have been crossed with a tester set of male sterile genes in an attempt to assign them to chromosomes. The tester set consists of a male sterile gene closely linked to the centromere of each of the 7 chromosomess: msg10 on chromosome 1, msg2 on 2, msg5 on 3, msg24 on 4, msgl on 5, msg6 on 6 and msg19 on 7.
A short awn mutant, designated lk,,f, was inherited independently of 6 of the male sterile genes and was linked with msg24 on chromosome 4. The F2 consisted of 104 Ms Lk : 48 Ms lk : 64 ms Lk : 9 ms lk plants. The Lk-lk alleles segregated in the expected 3:1 ratio (X2 value of 0.013), the Ms-ms alleles did not (X2 value of 6,650) and the two loci were not inherited independently of each other (X2 value of 9.661). Seed of 30 of the Ms lk plants were grown in F3 rows and 29 did not segregate for male sterility and only one did segregate. A recombination value of 22% is indicated by the F2 data and one of 2% is indicated by the F3 rows. Because the Ms-ms alleles did not segregate in the expected 3:1 ratio and only 30 F3 rows were grown, a valid recombination value can not be calculated. However, there is no doubt that lk,,f is linked with msg24 around the centromere of chromosome 4.
Litzenberger and Green (1951. Agronomy Journal 43: 117-123) reported that a short awn mutant, now designated lk5, was linked with the hooded locus on chromosome 4 with about 7% recombination. Tsuchiya (1974. BGN 4: 80-81) found that two other short awn mutants, ari-c and KM218, were allelic to lk5. The mutant lk,,f is being crossed with lk5 to determine if it is another mutant at the lk5 locus or if it occupies a different locus.
Ramage, Burnham and Hagberg (1961. Crop Science 1: 277-279) reported linkage values between the breakpoints of 5 translocations involving chromosome 4 and the hooded locus ranging from 4% to 23%. The translocations used and the magnitude of the recombination values observed suggest that the hooded locus would show linkage with the centromere of chromosome 4. Male sterile, short awn plants (msg24 lk,,f) are being crossed with hooded plants (K) to provide a 3-point linkage map of this portion of chromosome 4.