II.43. Further results on the allelic relationship between wst and wst 3.
T. Tsuchiya and Debra A. Jensen*. Colorado State University, Fort Collins, Colorado 80521, U.S.A.
* Undergraduate student at Colorado State University. Part of this experiment was conduated by Miss Debra A. Jensen as part of a project of Special Studies in Genetics (AG 495C).
In the previous paper of the senior author, the allelic relation of two white streaked mutants, wst and wst 3 was reported. In order to obtain more information, normal green uzu (uz, Baitori 10) and white streak (wst) were crossed and the F2 segregation has been studied with the results shown in Table 1.
Table 1. F2 segregation ratio of uz and wst crosses.
Takahashi (1972) reported that "several double recessive (recombinant) plants were found among about 600 F2 plants (in repulsion phase)". As seen in Table 1, no definite case of a double recessive plant has been found among 1429 F2 plants. Therefore, it is obvious that the two genes, uz and wst are very closely linked on chromosome 3. Takahashi (1972) found that F1 and F2 hybrids of wst x wst 3 were all white streak, yet wst 3 was completely linked with uz which is far from wst on the linkage map (Robertson, 1971). In a previous report (Tsuchiya, 1972) explained these conflicting results as being due to a paracentric inversion found in hybrids involving wst 3 in crosses. However, the results shown in Table 1 indicate that wst is very closely linked with uz, even if wst 3 (wst) and uz are not complete linkage. Addendum: A recent letter from Takahashi (dated March 22, 1973) tells me that the previous observation that several double recessive wst-uz plants were found among about 600 F2 from crosses between uz and wst seems to be wrong. Maybe the paracentric inversion found in the hybrids involving wst 3 (Tsuchiya, 1972) has nothing to do with the complete linkage of wst 3 (wst) and uz. A critical analysis of the paracentric inversion found in wst 3 is now under way by means of primary trisomic analysis.
All 342 F2 plants from the cross wst 3 x wst were white streak.
Robertson, D. W. 1971. Barley Genetics II:220-242.
Takahashi, R. 1972. BGN 2:127-131.
Tsuchiya, T. 1972. BGN 2:104-105, 163-167.
(Supported partly by NSF Research Grant GB30493.)
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