II.35. Karyotype analysis of telotrisomic type for telocentric chromosome 5A.
T. Tsuchiya. Agronomy Department, 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 Biomedical Science Support Grant (NIH) at Colorado State University No. 31-1801-4518 (1970-1971) and 31-1170-7213 (1971-1972)
Somatic chromosomes were studied in detail in root tip mitosis of telotrisomic plants for chromosome 5 (Telo 5A). This telotrisomic has very similar morphological characteristics to the primary trisomic for chromosome 5 with extremely revoluted narrow leaves and slightly yellowish green plant color. The fertility of the telotrisomic plants is very high.
It is well known that chromosome 5 is the shortest among the five non-satellited chromosomes and the short arm is the shortest of the ten arms of the five non-satellited chromosomes.
The length of the pair of chromosome 5 and the telocentric chromosome was measured in eight somatic cells of telotrisomic for Telo 5A with results shown in Table 1. In all six cells analyzed the length of the telosome was almost equal to the long arm of chromosome 5. It is therefore concluded that this telocentric chromosome is the long arm of chromosome 5 (Telo 5L).
Figure 1 shows the chromosomes of the telotrisomic for 5L.
Table 1. Measurement of the telocentric chromosome (5A) and the arm length of normal chromosome 5.
Figure 1. Chromosomes of telotrisomic for Telo 5A (5L) from two cells (a and b).
Fedak (1969) reported that trd, which is on the short arm of the present map (Robertson, 1971), gave a trisomic ratio in F2 of the cross between the above mentioned telotrisomic and trd. Telotrisomic analysis of f 7 for chlorina in Smyrna II and fs 2 for fragile stem 2 showed that the telocentric 5A carries f 7 and fs 2 of Oshichi-hen.
In combining the genetic data from telotrisomic analysis by Fedak (1969) and Tsuchiya (1972) with the present finding on the karyotype of the telotrisomic for 5L, the linkage map of chromosome 5 should be reversed as shown in Figure 2.
Figure 2. New linkage map (b) compared with the previous map (a) of chromosome 5.
Fedak, G. 1969. Ph.D. Thesis. Univ. Manitoba, Winnipeg, Canada. 110 pp. Mimeographed
Robertson, D W. 1971 Barley Genetics II:220-242.
Tsuchiya, T. 1972. BGN 2:93-98.
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