GrainGenes

II.48. Further information on telotrisomic analysis in barley.

T. Tsuchiya and R. J. Singh. Department of Agronomy, Colorado State University, Fort Collins, Colorado 80521, U.S.A.

The senior author reported the preliminary results of telotrisomic analysis of 34 genes in 7 telotrisomic lines (Tsuchiya, 1971, BGN 1: 61-62, 1972, BGN 2:93-98), and gave temporary assignment of those genes in chromosome arms of five chromosomes (Tsuchiya, 1972, BGN 2:93-98). Chromosome numbers were not studied in those F2 plants. In this report the results of critical analysis including chromosome counts in F2 plants are reported (Table 1). It should be remembered that if appreciable numbers of recessive homozygotes occur in trisomic plants in the F2 generation, the gene analyzed is not on the telocentric chromosome of the telotrisomic type.

TABLE 1. F2 segregation results in 35 combinations between seven telotrisomics and 35 marker stocks.

As shown in Table 1, the results from critical analysis are considerably different from the preliminary results without chromosome counts in F2 plants. The gene e for elongated glume awn (wide glume), which was believed to be on the long arm is located on the short arm, yet gs 5 for glossy sheath and spike is located on the long arm of chromosome 2. Thus, the gene order in the map should be changed (Tsuchiya, 1973 BGN 3:99-103).

The gene f for chlorina seedling showed trisomic ratio with Triplo 2B, which is therefore confirmed to be trisomic for Telo 2S.

Telotrisomic analysis of cu 2 and yst 2 with Telo 3A showed trisomic ratio, and al, yst, and x_c showed disomic ratio. Two recessive homozygotes for the gene f 2 for chlorina seedling segregated in the trisomic portion. More F2 data are needed to give definite conclusions on the arm location of f 2. These results are in conflict with the previously developed map of chromosome 3 based on conventional and translocation analysis (Robertson, 1971, Barley Genetics II:220-242; Takahashi, 1972, BGN 2:127-131; Tsuchiya, 1972, BGN 2:163-167). The telocentric chromosome is the long arm of chromosome 3 and carries yst 2 and cu 2, which was located at the distal end of the short arm (Takahashi, 1972, BGN 2:127-131; Takahashi, 1973, BGN 3:84). Thus, the centromere of chromosome 3 should be located between al and yst 2.

Only f 9 for chlorina seedling showed trisomic ratio with telotrisomic for Telo 4A which now should be Telo 4S. However, the morphology of the telotrisomic plants suggests that the telocentric chromosome may be the long arm of chromosome 4 (Telo 4L). Five genes (gl and gl 2, br 2, yh, lg 4, and zb_c) showed all disomic ratio. The analysis of Kk locus is critical for exact location of the centromere in the linkage map of chromosome 4.

The results of telotrisomic analysis with telotrisomic for Telo 1L and Telo 5L was reported (Tsuchiya, T., 1972, Seiken Ziho 23:47-62; Tsuchiya, T., 1972, J. Hered. 63:373-375).

The results are summarized in Table 2 and linkage maps developed from the results of telotrisomic analysis are shown in Figure 1. (Supported partly by NSF Research Grant GB30493 to T. Tsuchiya.)

TABLE 2. Summary of the results of telotrisomic analysis of 32 genes using seven telotrisomics.

Figure 1. Linkage maps prepared by the data obtained from telotrisomic analysis.

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