23. Allelism of genes for elongation of uppermost internode from two different sources

Masahiko MAEKAWA1, Toshihiko MAEKAWA2, Noboru SHINBASHI3 and T. KINOSHITA4

1) Agricultural Experiment Farm, Hokkaido University, Sapporo, 060 Japan

2) Plant Genetic Resources Center, Takikawa, Hokkaido, 073 Japan (presently: Kitami Agric. Exp. Station, Tokoro, Hokkaido, 099-14 Japan)

3) Hokkaido Green-Bio Institute, Naganuma, Hokkaido, 069-13 Japan

4) Plant Breeding Institute, Faculty of Agriculture, Hokkaido University, Sapporo, 060 Japan

Rutger and Carnahan (1981) reported that elongation of the uppermost of first internode was controlled by a recessive gene eui. At Hokkaido Plant Resources Center, a plant of variety Ishikari with noticeably elongated first internodes was found, which seemed to have arisen as a spontaneous mutant. Its progeny true-breeding for this trait was called No.615. Maekawa and Kita(1983) found that the elongation of first internode in this line was controlled by a single recessive gene, which belonged to linkage group VI+IX. The gene was linked with nl-1 (neck leaf-1) and ri (verticillate rachis), the recombination values being 23.7+/-5.1% and 28.6+/- 5.1%, respectively.

Rutger and Carnahan's line PI-1 with eui was made available through their courtesy, and it was crossed with No. 615. The material was grown in a vinyl house in 1988 at Sapporo.

When No. 615 was compared with Ishikari, its "panicle-exserted length", as shown by first-internode length minus flag-leaf-sheath length, was much longer than that of Ishikari (Table 1). However, the proportion of first internode length to culm length did not differ much among No. 615 (55%), Ishikari (50%), Pl-1 (50%), and No. 615 X Pl-1 F1 plants (48%). Therefore, the panicle-exserted length was taken as showing the expression of genes for internode elongation, and was assessed in the F1 and F2 plants from No.615 X Pl-1 and their parents. The results are shown in Fig. 1 together with the variation in days to heading. The F1 plants had almost the same panicle exsertion length as of Pl-1 although they differed in the days to heading, and the F2 plants were distributed largely in the

Table 1.Characters of Pl-1,No.615,F1 of No.615XPl-1 and Ishikari
________________________________________________________________
Character            Pl-1     No.615     F1      Ishikari

Length(cm),
  Culm                110         72     106        54
  1st internode        56         39      51        27
  Flag leaf sheath     36         27      31        24
  Panicle-exserted     20         12      20         3
Days to heading       130         85     110        86
________________________________________________________________

Fig. 1. The F1 and F2 plants from No. 615 x Pl-1 and their parental plants scattered according to panicle-exserted length and days to heading.

parental range.

Accordingly, it was assumed that the uppermost-internode elongating gene of No, 615 was allelic to eui of Pl-1. This was supported by the trisomic analysis made by Librojo and Khush (1986) who reported that gene eui was located on chromosome 5, which corresponds to linkage group VI+ IX. As there is no particular difference in gene action, the recessive gene for internode elongation carried by No. 615 may also be called eui.

References

Librojo, A. L. and G. S. Khush, 1986. Chromosomal location of some mutant genes through the use of primary trisomics in rice. In Rice Genetics, p. 249-255. IRRI, Manila.

Maekawa, M. and F. Kita, 1983. Interaction of eui gene for the elongation of uppermost internode and some genes for elongation of internode. Jpn. J. Breed. 33 (Suppl. 1): 124-125. (in Japanese)

Rutger, J. N. and H. L. Carnahan, 1981. A fourth genetic element to facilitate hybrid cereal production. A recessive tall in rice. Crop Sci. 21: 373-376.