II.42. Cytological identification of a translocation accompanied by a gene mutation.
T. Tsuchiya. Department of Agronomy 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).
Supported in part by a Research Grant from Faculty Improvement Committee (FIC), Colorado State University, No. 13-2018-0550.
KM (K mut) 21b is a radiation-induced "male" (or ovary-less) mutant which was accompanied by a reciprocal translocation in X3 when this mutant was first found (Tsuchiya, 1962, 1969). At diakinesis the quadrivalent was associated with the nucleolus in the mutant plant. It has therefore been known that one of the translocated chromosomes is chromosome 6. The new translocation is designated at RT x-6. Crosses were made between plants homozygous for RT x-6 and five previously established translocation stocks. Meiotic configurations of F1 hybrids were studied with the results shown in Table 1.
From the results obtained, the unknown chromosome (x) involved in this new translocation (RT x-6) was determined to be chromosome 4. The new translocation is designated T-4-6i by R. T. Ramage, the Coordinator for Translocation Stocks (BGN 2:135-137).
Detailed karyotype analysis showed that the long arm of chromosome 6 is shorter than the normal one and one arm of chromosome 4 is longer than normal. It was, however, not possible to determine which arm of chromosome 4 is involved in this translocation.
