II.37. Trisomic analysis of a short awned mutant in barley.
T. Tsuchiya and R. J. Singh. Agronomy Department, Colorado State University, Fort Collins, Colorado 80521, U.S.A.
*Reports II.33. (p.80) through II.42. (p.108) by T. Tsuchiya and co-workers are based on the results of researches supported by NSF Research Grants GB4482X and GB30493 and Colorado State University Experiment Station Project (Hatch 8).
The association of a short awn gene to a specific chromosome in barley was tried by means of the trisomic analysis. The short awned mutant (KM 200) was produced in a spring type cultivar, Hakata No. 2. The short awn gene is incompletely dominant with the heterozygote having medium awns (Tsuchiya, 1962). The segregation for long, medium, and short awn was recorded in the F2 segregating populations of the crosses of primary trisomics for chromosome 3 (Pale), chromosome 4 (Robust), chromosome 5 (Pseudonormal), chromosome 6 (Purple) and chromosome 7 (Semierect) with homozygous mutants of KM 200. The chi-square values were calculated, based on the 3:1 expectation. No trisomic ratio was observed for the five trisomic types, as presented in the following table:
The Semierect population was not large enough. However, it was concluded that this gene is not located on chromosome 7 because an appreciable number of trisomic plants were homozygous for the mutant gene.
The above data indicates that the short awn gene may be located on chromosome 1 or on chromosome 2. Homozygous short awn plants have been crossed with telotrisomics for both arms of chromosome 1 and chromosome 2. In this way, it will be possible to locate this gene on a particular arm of these chromosomes.
Tsuchiya, T. 1962. Radiation breeding in two-rowed barley. Seiken Ziho 14:21-34.
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