13. Linkage analysis for a semidwarfing gene sd-1 on chromosome 1

Atsushi FUKUCHI1, Atsushi NAKAMURA2*, Hisashi HIRAN03, Hirohiko HIROCHIKA3 and Fumio KIKUCHI2

1) Agricultural Research Laboratories, Takeda Chemical Industries, Ltd., Tsukuba, Ibaraki, 300-42 Japan

2) Institute of Agriculture and Forestry, University of Tsukuba, Tsukuba, 305 Japan

3) Department of Molecular Biology, National Institute of Agrobiocical Resources, Tsukuba, 305 Japan

* Present address: Life Science Laboratory, Mitsui Toatsu Chemicals Inc., Mobara, Chiba, 277 Japan

Most of the semidwarf rice varieties have gene sd-1 which was originally transferred from a Chinese semidwarf cultivar Dee-geo-woo-gen. The sd-1 gene is located on chromosome 1.

By using the hybrid populations between Japanese tall cultivar Norin 29 and its near-isogenic line SC-TN1, sd-1 was found to be linked with Srp gene which determines the basic glycoproteins of the embryo (Nakamura et al. 1991). In addition, we also found the linkage between sd-1 and the retrotransposon of rice (Hirochika et al. 1992) specific probe-related RFLP (Tos 1-related RFLP).

To determine the linkage relations among three loci (sd-1, Srp and Tos 1- related RFLP), the F2 Population of a cross between SC-TNL and Norin 29 was used. The genotypes for sd-1 were estimated by the progeny tests of F2 plants.

Recombination values were computed by the MAPL program of Ukai et al. (1991). The recombination values between sd-1 and Srp, sd-1 and Tos 1-related RFLP, and Srp and Tos 1-related RFLP were estimated to be 28.4+/- 5.3%, 26.1+/-3.8% and 20.7+/-4.9%, respectively (Table 1).

Fig. 1 shows the relative positions of the three loci.


Fig. 1. Relative positions of sd-1, Srp and Tos1-related RFLP on chromosome 1. *: Calculated by Nakamura et al. (1991) 

Table 1. Cosgregation of sd-1, Srp and Tos1-related RFLP in the F2 of
SC-TN1/Norin 29
====================================================================
Gene pair     Segregation in the F2 population           X2 (1:2:1:2:  Recomb.  
A/B        =============================================    4:2:1:2:1) value(%)
           AABB AABb AAbb AaBB AaBb Aabb aaBB aaBb aabb Tot.
===============================================================================
Sd-1/Srp     5    6    1    3    8   4    1     7   11  46  30.1***  28.4+/-5.3
Sd-1/Tos1a  12    6    4   10   37   5    3    11   16 104  35.7***  26.1+/-3.8
Tos1/Srp     6    2    1    4   16   2    2     3   10  46  31.0***  20.7+/-4.9
===============================================================================
a: Data quoted from Fukuchi et al. (in preparation)
***: significant at 0.1% level.
The authors are indebted to Dr. R. Ohsawa for calculating recombination values by their MAPL program.

References

Hirochika, H., A. Fukuchi and F. Kikuchi, 1992. Retrotransposon families in rice. Mol. Gen. Genet. 233: 209-216.

Nakamura, A., H. Hirano and F. Kikuchi, 1991. A protein gene Srp(t) linked with a semidwarfing gene sd-1 in rice (Oryza sativa L.). Jan. J. Breed. 41: 517-521.

Ukai, Y., R. Ohsawa and A. Saito, 1991. MAPL: A package of microcomputer programs for RFLP linkage mapping. RGN 8: 155-158.