II.34. Genetics of uz, uz2 and uz3 for semi-brachytic mutations in barley.
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).
Takahashi (1942, 1951) and Takahashi and Yamamoto (1951) studied in detail the characteristics, inheritance and linkage of uz gene for uzu or semi-dwarf in Japanese barley varieties. Later Leonard et al. (1957) and Garza-Falcon (1960) claimed that they had found two additional genes, uz2 and uz3, for the uzu character based on the study of plant height only (Robertson, 1963). Takahashi (1951) had thoroughly studied the effects of l and lk2 (lk) genes on the character expression of the uz gene. Also, he clearly demonstrated the diagnostic qualitative traits such as the hook or projection characteristic of the uzu mutant in addition to some quantitative traits such as short rachilla, short coleptile, short glume and glume awn, short and wide leaves (Takahashi, 1942).
However, most research workers who have been using uzu plants are not aware of the characteristics very well; the qualitative character such as the hook expression has been ignored almost completely (Leonard et al. 1957; Garza-Falcon, 1960; Nilan, 1964). This unawareness of a diagnostic characteristic and probably the manifold effects of L l alleles have led these workers to the conclusion that there were two additional uz genes, namely uz2 and uz3 (Leonard et al. 1957; Garza-Falcon, 1960; Robertson et al. 1965).
The present writer has conducted a critical study of this problem by repeating the same crosses as made by the previous workers. The preliminary results indicate that there is only one uz gene for the uzu character.
Table 1 shows the previous genotypes of the three varieties based on the results given by Leonard et al. (1957) and Garza-Falcon (1960) (Robertson et al. 1965).
Table 1. Three uzu-type varieties used in this experiment and their genotypes based on the proposed gene symbols for uzu genes.
Table 2 gives the proposed genotypes of F1 hybrids and expected segregation of characters in F2 in five cross combinations among those three varieties, based on the parental genotypes given in Table 1.
Table 2. Proposed F1 genotype and expected F2 segregation based on the proposed parental genotypes (Table 1).
In Table 3 are the results obtained in F1 and F2 hybrids in the present experiment. The coleoptile lengths of all F1 plants from the five crosses were very similar to each other and slightly shorter than the parental varieties. The shorter coleoptile length of these F1 hybrids could be ascribed to the slightly smaller size of the crossed seeds resulting from the clipping method of emasculation. All or most of the plants showed the diagnotic hook or notch in the coleoptile (Table 3). About 150 F2 plants were raised from all five cross combinations. There was no segregation for coleoptile characteristic in these F2 plants.
Table 3. Coleoptile length and qualitative characters in the F1 and F2 hybrids and their parental uzu-type varieties.
The results indicate that all three parental varieties used in this experiment had one and the same uz gene. There was no segregation for uz2 or uz3 genes as far as these three varieties were concerned.
Garza-Falcon, E. 1960. M. S. Thesis, Colorado State University. Mimeo. pp.57.
Leonard. W. H., D. W. Robertson and H. O. Mann. 1956. Jap. J. Genet. 31:229-240.
Leonard, W. H., H. 0. Mann and L. R. Powers. 1957. Colorado Agr. Exp. Sta. Tech. Bull. 60:1-24.
Robertson, D. W., R. G. Shands and G. A. Wiebe. 1965. Crop Sci 5:33-43.
Takahashi, R. 1942. Ber. Ohara Inst. landw. Forsch. 9:71-90.
Takahashi, R. 1951. Ber. Ohara Inst. landw. Forsch. 9:383-398.
Takahashi, R. and J. Yamamoto. 1951. Ber. Ohara Inst. landw. Forsch. 9:399-410.
Takahashi, R., J. Yamamoto, S. Yasuda and Y. Itano. 1953. Ber. Ohara Inst. landw. Forsch. 10:29-52.
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