III. Gene location and trisomics

27. Arm location of Adh-1 and Sdh-1 isozymes using secondary trisomics

Kuldeep SINGH, Benildo delos REYES, Darshan S. BRAR and Gurdev S. KHUSH

International Rice Research Institute, P. O. Box 933, Manila, Philippines

The isozyme loci Adh-1 and Sdh-1 have been located on chromosomes 11 and 12, respectively (Ranjhan et al. 1988 ; Pham et al. 1990). However, arm locations of most of the isozymes loci are not known. We used secondary trisomics to locate these two isozymes to specific chromosome arms. The secondary trisomics for the short and long arms of chromosome 11 (2n+11S 11S and 2n+11L 11L) and secondary trisomic for the short arm of chromosome 12 (2n+12S 12S) were corssed with cultivar MaHae which is polymorphic with IR36 for these isozymes. The F1 secondary trisomics were confirmed cytologically and analyzed for Adh-1 and Sdh-1 isozymes as described by Ranjhan et al. (1988).

Heterozygous secondary trisomic 2n+11S 11S showed higher dosage of IR36 allelle for Adh-1, while 2n+ 11L 11L showed same intensities of IR36 and MaHae alleles as is in F1 disomic sib (Fig. 1). The Adh-1 is therefore located on the short arm of chromosome 11. Secondary trisomic 2n+12S 12S showed higher dosage of IR36 allele for Sdh-1 compared to MaHae allele (Fig. 2) and is, therefore, located on the short arm of chromosome 12.

 

References

Ranjhan, S., J. C. Glaszmann, D. A. Ramirez and G. S. Khush, 1988. Chromosomal location of four isozyme loci by trisomic analysis in rice (Oryza sativa L.). Theor. Appl. Genet. 75: 541-545.

Pham, J. L., J. C. Glaszmann, R. Sano, P. Ghesquiere and G. Second, 1990. Isozyme markers in rice: genetic analysis and linkage relationship. Genome 33: 348-359.