18. Linkage analysis of the Pgd-1 locus

R. Ishikawa-1, T. Kinoshita-2, and H. Morishima-3

1) Faculty of Agriculture, Hirosaki University, Hirosaki, 036 Japan

2) Faculty of Agriculture, Hokkaido University, Sapporo, 060 Japan

3) National Institute of Genetics, Misima, 411 Japan


The Pgd-1 locus for phosphogluconate dehydrogenase isozymes was found to belong to linkage group VIII by trisomic analysis (Ishikawa et al, 1986). For mapping this locus on the chromosome, IR 35 (Pge-12/2) was crossed with a Japonica linkage tester FL280 (Pgd-11/1) which carried two marker genes both belonging to linkage group VIII, la (Lazy) and v-4 (virescent). The F\2\ segregation pattern obtained from this cross indicated that Pgd-1 was linked with these two markers. Recombination values were calcultaed by using the maximum likelihood formula given by Allard (1956) to be 14.2+=4.9% between Pgd-1 and la, 5.4+=3.0% between Pgd-1 and v-4, and 9.0=+4.0% between la and v-4 (Table 1). Accordingly, the three lcoi are situated as shown in Fig. 1.

Adh-1 (alcohol dehydrogenase) was found to be located on the same chromosome recently (Ranjhan et al. 1988). In the cross between an Indica (Ac224) and a Japonica (Ac647) strain, F\2\ segregation was observed for two linked isozyme loci, Pgd-1 and Adh-1. From the F\2\ data for the two loci (Table 2), their recombination value was estimated to be 19.4+=0.03%. But the location of Adh-1 can be determined after obtaining its linkage relation with v-4 or la.


Table 1. Segregation for three loci, la (lazy), v-4 (virescent), and Pgd-1 in the F\2\ of FL280 x IR36






Fig. 1. Mapping of three loci in linkage group VIII.





Table 2. Segregation for Pgd-1 and Adh-1 in the F\2\ of Ac224 X Ac647




References

Allard, R.W., 1956. Formulas and tables to facilitate the calculation of recombination values in heredity. Hilgardia 24(10):235-278.

Ishikawa, R., K. Kinoshita and H. Morishima, 1986. A preliminary report on trisomic analysis of genes for isozymes. RGN 3: 53-55.

Ranjham, S., J.C. Glaszmann 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.