BGN 2: A case of paracentric inversion affecting genetic behavior of a white streak gene BARLEY GENETICS NEWSLETTER, VOL. 2, II. RESEARCH NOTES
Tsuchiya, pp. 104-105

II.40. A case of paracentric inversion affecting genetic behavior of a white streak gene.

T. Tsuchiya. Department of Agronomy, 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).

The lack of allelism testing has caused some confusion in barley genetics. A gene for the grandpa character (gp 2), which was said to be located on chromosome 6 (Walker et al, 1963), was proved to be allelic to the grandpa gene (gp) in the long arm of chromosome 2 (Matchett et al., 1971; Tsuchiya, 1971). Two glossy seedling genes (gl and gl 2) both of which were located on chromosome 4 were found to be allelic to each other (Haus and Tsuchiya, 1972). The Genetic Stock Center has started extensive allelism testing for similar type mutants not only for the ones on the same chromosome or same arm but also for the ones located on the different chromosomes (Tsuchiya, 1972).

The first white streak gene (wst) was located in chromosome 3 by Robertson (1967). In 1969 another white streak gene (wst 3) was also reported to be located on chromosome 3 by Takahashi and Moriya (1969). They also reported that wst 3 is completely linked with uz on chromosome 3, since no recombinant was obtained in more than 4000 F2 from the cross between tall and green (Uz Wst 3) and white streak-uzu double recessive (uz wst 3).

The genetic stock for white streak (wst) was crossed with the one for white streak 3 (wst 3) as a part of overall allelism testing of all white streak mutants in the Barley Genetic Stock Center in Fort Collins, Colorado. The F1 hybrids between wst 3 and wst showed the white streak characters (Tsuchiya, 1972a) and all plants in F2 populations were white streak. The same results were also obtained by Takahashi (1972) who also reported that recombinants of wst and uz were obtained in the F2 population from the cross Uzwst x uzWst.

Based on these results, it was assumed that there might be some kind of chromosome aberration involved in this case. An inversion was particularly considered as a possible cause of this complication.

Meiosis of F1 hybrids between wst 3 and various barley lines including wst were studied with the results confirming the above assumption.

At anaphase I of meiosis a bridge-fragment figure was observed in about 25% of the sporocytes. This result indicates that there is a paracentric inversion in the stock for wst 3. Since the fragment is rather large the inverted segment must be quite long. Thirty sporocytes studied at metaphase I showed no abnormality; seven normal bivalents were observed in all cells.

Pollen fertility and the seed set of F1 hybrids between wst 3 and other varieties were 91.0% and 88.0% respectively.

Since wst 3 was induced by x-ray treatment in the uzu type cultivar, Akashinriki, it may be reasonable to assume that the gene mutation (wst 3) and a paracentric inversion had occurred in chromosome 3 at the same time, although a critical experiment should be conducted to confirm this assumption.

Recently the author also found a case of spontaneous translocation in a genetic stock for purple lemma and pericarp (Re 2) (Tsuchiya, 1972b).

The occurrence of gene mutations accompanied by chromosome aberrations are not infrequent in radiation and other mutagen treated populations as shown in barley (Hagberg, 1960; Holm, 1960). The finding of a spontaneous translocation in the Re 2 stock, and an inversion reported in this article, together with previously reported cases, it may be reasonable to assume additional chromosomal aberrations such as inversions and translocations might be found in other genetic stocks used or to be used in genetic studies of barley. It is suggested, therefore, that a cytological study in one way or another should be conducted even in the conventional genetic analysis using diploid materials in barley. A study of the chromosome configuration at mataphase I, chromosome behavior at anaphase - telophase I and II and/or pollen fertility will give some information as to whether or not a detectable chromosome abnormality is present.


Habgerg, A. 1960. Genet. Agr. 12:319-336.

Holm, G. 1960. Hereditas, 46:274-278.

Matchett, R. W , H. G. Nass and D W. Robertson. 1971. Can. J. Genet. Cytol 13:489-498.

Robertson, D. W 1967. Crop Sci. 7:41-42.

Takahashi, R. 1972. BGN 2:127-131.

Takahashi, R. and I Moriya. Ber. Ohara Inst. landw. Biol. 15:35-46.

Tsuchiya, T. 1972a. BGN 2:80-87.

Tsuchiya, T. 1972b. BGN 2:105-107.

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