II.36 "Univalent shift" in telotrisomic barley.
T. Tsuchiya, Agronomy Department, Colorado State University, Fort Collins, Colorado 80521, U.S.A.
In the F2 population of a cross between telotrisomic for chromosome 1S (short arm of chromosome 1) and a chlorina mutant (f8) in Comfort II, the following results were obtained (Table 1):
Table 1. Chromosome constitution of F2 plants of 14 + 1 telo 1S x f8f8
As shown in Table 1 a considerable number of plants with 14 + 1 telo
1L were obtained in this population. Telotrisomics for 1L were easily distinguished
from telotrisomics for 1S by the diagnostic traits shown in plants of the
former compared to the latter which does not show any distinctive characteristics.
No telotrisomic for 1L was obtained in the parental stock of telotrisomic
for 1S. These results suggest that the chromosome 1 of f8 genotype
may have a tendency to misdivide at the centromere to give telocentric
chromosomes. It is noteworthy in this connection that an unusually high
frequency of telotrisomic plants (60%) was obtained in this population.
There are many questions to be answered before any definite conclusions
are given. It is, however, safe to say that there is "univalent shift"
for telocentric of chromosome 1 from Telo 1S to Telo 1L in a particular
genetic background. The occurrence of a plant with 2n = 13 + 2 Telos (most
likely Telo 1L + Telo 1S) (II.35 of this issue of BGN) and the "univalent
shift" reported here suggest the frequent occurrence of misdivision at
the centromere of chromosome 1, at least under certain genetic backgrounds.
Reports II.29 (P. 58) through II.39 (P. 66) by T. Tsuchiya and coworkers are based on the results of researches supported partly by NSF Research Grant GB 4482 X.
