26. Integration of conventional and RFLP linkage maps in rice, III. Chromo- somes 5, 7, 8 and 12

Faculty of Agriculture, Kyushu University, Fukuoka, 812 Japan

Eleven conventional markers and 22 RFLP markers (Saito et al. 1991) of chromosomes 5, 7, 8 and 12 were mapped in this study. Six populations were studied, which were from the crosses between an Indica variety IR24 and Japonica lines with different conventional markers. The marker genes segregating in the F`2` populations were d-1, spl-7 and nl-1 of chromosomes 5, v-11, spl-5, g-1 and d-6 of chromosome 7, sug and v-8 of chromosome 8, and rl-1 and spl-1 of chromosome 12. The results of this study are shown in Fig. 1 with conventional and RFLP maps.

Fig. 1. Arrangement of conventional, RFLP and integrated linkage maps on chromosomes 5, 7, 8 and 12 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 (Chromosomes 5 and 7: Iwata et al. 1984. Marker genes of chromosome 8: Iwata and Omura 1984 and chromosome 12: Iwata and Omura 1975) 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, XNpb, are omitted in this figure. The loci in ellipses are morphological markers used in this study, and in boxes are RFLP markers.

For chromosomes 5 and 7, the orientation of the conventional map and the RFLP map was completely understood. For chromosome 7, there were no markers on the RFLP map (Saito et al. 1991) corresponding to the region spl-5-g-1-d-6 on the conventional map. XNpb50 which was assigned to chromosome 7 by trisomic gene dosage analysis (Ideta et al. 1990) was located at the terminal end of the integrated map. The linear order of spl-5-d-6-g-1-XNpb50 on the integrated map in this study was different from that of spl-5-g-1-d-6 found on the conventional map. More investigation on the order of d-6 and g-1 is needed. The genes sug and v-8 of chromosome 8 and rl-1 and spl-1 of chromosome 12 which were assigned to their respective chromosomes by trisomic analysis (Iwata and Omura 1975, 1984) were aligned on the integrated map with some RFLP markers.

In the series of these studies on the integration of conventional and RFLP linkage maps (Ideta et al. 1992, 1993 and present study), we have constructed 12 integrated maps consisting of 34 conventional markers and 74 RFLP markers. Fine mapping near the specific gene region is under way aimed at obtaining basic linkage information for map-based cloning.

References

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Ideta, O., A. Yoshimura, T. Matsumoto, H. Tsunematus, H. Satoh and N. Iwata, 1993. Integration of conventional and RFLP linkage maps in rice, II. Chromosomes 6, 9, 10 and 11. RGN 10:87-89.

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