IV.7 Coordinator's report: Translocations and balanced tertiary trisomics.
R.T. Ramage. Department of Plant Sciences, University of Arizona, Tucson, Arizona 85721, U.S.A "R"
During 1975 two translocations were identified and added to the World Collection. They were given the designations T2-3ag and T6-7aq.
The shrunken endosperm mutant seg6f was found to be homozygous for a translocation (Ramage and Scheuring, BGN 6: 59-60). The seg6f mutant and the translocation are of spontaneous origin in material of hybrid origin. The translocation was identified by Ramage and Clark (BGN 6: 58) as T2-3ag. In T2-3ag, no discernible difference in chromosome morphology was observed. The stock which is homozygous for both seg6f and T2-3ag had been crossed with normal Betzes to separate the shrunken endosperm mutant from the translocation.
The translocation T6-7aq is of spontaneous origin in the cultivar Betzes C.I. 6398. The translocation was isolated by Cheng-Wou Yu (M.S. Thesis, Montana State University, 1971) and identified by Clark and Ramage (BGN 6: 9). The break-points of T6-7aq are probably either Short-Short or Long-Long.
Last year, Ramage and Jones (BGN 5: 44-56) reported the establishment of three balanced tertiary trisomics that have an extra T27d chromosome and two normal chromosomes carrying recessive male sterile and albino seedling alleles. At that time, allele tests between the three albino seedling genes had not been completed. Allele tests have been completed and the three albino seedling genes occupy three different loci (BGN 6: 8 ). We have designated the three BTT stocks as having an extra T27d chromosome and being balanced for msg2-a369, for msg2-a253 and for msg2-a143. The a 369 mutant is allelic to the alb,,p mutant described by Rahman and Eslick (BGN 6: 53-58).
Limited amounts of seed of the translocations and balanced tertiary trisomic seed stocks are available upon request.