II.13. A light green, dwarf mutant located on chromosome 2.
R. T. Ramage and P. Curtis. Department of Plant Sciences, University of Arizona, Tucson, Arizona 85721, U.S.A. "R"
We obtained a backcross-derived line of two-row Glacier from R. F. Eslick, Montana State University, and had it treated with 800 rads of fission neutrons at Oak Ridge National Laboratory. We selected 26 mutants for characters that might affect yield or yield components when grown under different environments. Six were mutants for early flowering, six were dwarfs, five were erectoides, three had elongated outer glumes, two had short awns, two were male sterile, one was uniculm and one was a light green dwarf. All of the 26 mutants were monofactorial recessives. The purpose of the project is to establish both two-row and six-row isogenic lines for each of the mutants. All of the mutants were crossed to normal six-row Glacier and the Fl's were backcrossed to six-row Glacier. From the F2 of the last backcross, the four possible isogenic lines are being selected. The crosses and backcrosses are segregating for both the mutants and the row number character and provide an opportunity to check each mutant for linkage with the row number locus which is carried on chromosome 2.
We have conducted allele tests among the six early mutants, the three elongated outer glume mutants and the two male sterile mutants. All six of the early mutants are allelic, all three of the elongated outer glume mutants are allelic and the two male sterile mutants are non-allelic. Allele tests between members of the other mutant classes are being conducted.
All three of the elongated outer glume mutants, which are allelic, were linked with the row number locus. This is expected if the mutants are also allelic to the elongated outer glume locus that is carried near the centromere of chromosome 2. All of the other mutants were inherited independently of the row number locus except for the light green dwarf mutant. This mutant was linked with the row number locus with .15 + .051 recombination. We are growing progenies of crosses to orient the light green dwarf mutant in relation to the male sterile locus msg2, which is located near the centromere, and the row number locus V, which is located in the long arm about 26 recombination units from the centromere.