18. Integration of conventional and RFLP linkage maps in rice, II. Chromosomes 6, 9, 10 and 11

Faculty of Agriculture, Kyushu University, Fukuoka, 812 Japan

We have been trying to untegrate the conventional linkage map and the RFLP linkage map in rice (Ideta et al. 1992). Nine marker genes and 20 RFLP markers were mapped together. Five F\2\ populations were observed, which were between an Indica variety IR24 and Japonica marker lines with different genetic markers and RFLP markers (Saito et al. 1991). The markers segregating in the F\2\ populations were as follows: chromosome 6, dp-1 and spl-4; chromosome 9, I-Bf, dp-2 and drp-2; chromosome 10, pgl and spl-10; and chromosome 11, z-2 and v-9. The RFLP markers without prefix XNpb are shown in Fig. 1. On chromosome 6, a low degree of saturation was found out for the RFLP linkage

Fig. 1. Arrangement of conventional, RFLP and integrated linkage maps on chromosomes 6, 9, 10 and 11 in rice. Numbers at the top indicate chromosomes. For each chromosome, the integrated map is shown in the center, the conventional linkage map or marker genes (Chromosome 6, Chromosome 9 and Chromosome 11: Iwata et al. 1984. The gene I-Bf on chromosome 9 and marker genes on chromosome 10 (except spl-10: Iwata and Omura 1984) are on the left and the RFLP linkage map (Saito et al. 1991) is on the right. The letters of prefix of the RFLP markers, MNpb, are omitted in this figure. The loci in ellipses are morphological markers used in this study, and in boxes are RELP markers.

map. The RFLP map lacked the region corresponding to wx--dp-1--spl-4 region on chromosome 6 in the conventional linkage map. But a locus cmWX is mapped in the RFLP linkage map. The dependence between wx locus and cmWX locus must be investigated. On chromosome 9, the relationship between I-Bf locus and Dn-1--drp-2--dp-2 linkage group was established. On chromosome 10, tight linkage was found out between spl-10 and pgl which were assigned to the chromosome by trisomic analysis. Gene spl-10 is a newly induced spotted leaf mutant obtained by treating fertilized egg cells with N-methyl-N-nitrosourea (MNU). On chromosome 11, the orientation of both maps estimated by Yoshimura et al. (1992) was confirmed.

References

Ideta, O. A. Yoshimura, T. Matsumoto, H. Tsunematsu and N. Iwata, 1992. Integration of conventional and RFLP linkage maps in rice, I. Chromosomes 1, 2, 3 and 4. RGN 9: 128-129.

Iwata, N. and T. Omura, 1984. Studies on the trisomics in rice plants (Oryza sativa L.). VI. An accomplishment of a trisomic series in japonica rice plants. Japan. J. Breed. 59: 199-204.

Iwata, N., H. Satoh and T. Omura, 1984. The relationships between chromosomes identified cytologically and linkage groups. RGN 1: 128-132.

Saito, A., M. Yano, N. Kishimoto, M. Nakagahra, A. Yoshimura, K. Saito, S. Kuhara, Y. Ukai, M. Kawase, T. Nagamine, S. Yoshimura, O. Ideta, R. Ohsawa, Y. Hayano, N. Iwata and M. Sugiura, 1991. Linkage map of restriction fragment length polymorphism loci in rice. Japan. J. Breed. 41: 665-670.

Yoshimura, S., A. Yoshimura, A. Saito, N. Kishimoto, M. Kawase, M. Yano, M. Nakagahra, T. Ogawa and N. Iwata, 1992. RFLP analysis of introgressed chromosomal segments in three near-isogenic lines of rice for bacterial blight resistance genes, Xa-1 Xa-3 and Xa-4. Jpn. J. Genet. 67: 29-37.