II.31. Induction of telotrisomics.
H. I. Sayed and S. B. Helgason. Department of Plant Science, University of Manitoba, Winnipeg, Canada, R3T 2N2.
Trisomic lines for each of chromosomes 1, 3, 4, 5, 6 and 7 of barley were subjected to EMS, DES, HA, FUdR and X-rays with the objective of inducing telocentrics in the chromosomes. The X-ray treatment (150 Rads at the seedling stage) produced a significant increase in fragments in Trisomic 7, all of which were telocentrics or acrocentrics. Trisomic 1 also yielded a significant increase in fragments from X-rays (500 Rads), one of which was a telocentric. While other treatments yielded fragments, telocentrics among them, they could not be definitely attributed to the treatments. The limits to sample size create problems, since morphological effects of telotrisomics are generally too slight to make visual selection effective.
Of 33 lines carrying fragments, 17 were telotrisomics. They were shown to represent 11 distinct chromosome arms, and account for all but the short arms of chromosomes 2 and 4, and the long arm of chromosome 7, of the potential telotrisomic set in barley. Seed is not yet in sufficient supply to meet requests for stocks.