1) Faculty of Agriculture, Hirosaki University, Hirosaki, 036 Japan
2) National Institute of Genetics, Mishima, 411 Japan
Two isozyme loci Pdg-1 and Adh-1 were found to belong to linkage group VIII by trisomic analysis (Ranjhan et al. 1988; Ishikawa et al. 1989). First, for mapping these loci, a Japonica linkage tester FL280 carrying Adh-12, Pgd-12, la (lazy habit) and v-4 (virescent-4) was crossed with an Indica strain Ac437 carrying Adh-13 and Pgd-11. In the F2, Adh-1 was found to be linked with v-4 (Table 1a), but not with la. The recombination value between Adh-1 and v-4 was 26.8+/-5.3%. As reported earlier (Ishikawa et al. 1988), Pgd-1 is linked with both la (14.2+/-4.9%) and v-4 (5.4+/-3.0%). Accordingly, the locations of these four loci are as as shown in Fig. 1.
Second, Acp-1 and Pox-2 belonging to the linkage group of d-33 were reexamined. A Japanica tester FL27 carrying d-33, Acp-19 and Pox-20 was crossed with an Indica strain Ac435 carrying Acp-14 and Pox-24C In the F2, d-33 showed linkage with both Acp-1 (29.2%+/-3.9%) and Pox-2(7.6+/- 0.1%; Table 1 b). In this cross, the recombination value between Acp-1 and Pox-2 was found to be 23.9+/-3.6%, which was lower than the values (27-34%) reported by Pai et al. (1975) in two crosses between cultivated and wild rice strains and also the value (28%) found in a cross between two Indica varieties by Wu et al. (1988). The differences between these estimates are probably due to segreation distortion frequently found in Indica-Japonica crosses. The gene order of the three loci may be: d-33-Pox-2
Table 1. Linkage relations and recombination values (p) obtained in two crosses a) FL280 (Adh-12;v-4) X Ac437 (Adh-13; + v-4) ________________________________________________________________ v-4 Adh-1 Total p(%) 3/3 3/2 2/2 ________________________________________________________________ Normal 27 33 6 66 26.8+/-5.27 Virescent 3 11 12 26 Total 30 44 18 92 ________________________________________________________________ b)FL27(d-33;Acp-19;Pox-20)xAc435(+d-33;Acp-1-4;Pox-24c) ________________________________________________________________ Gene linked Acp-1 Total p(%) -4/-4 -4/+9 +9/+9 ________________________________________________________________ Pox-2 4C 46 78 19 143 23.9+/-3.58 0 3 12 21 36 d-33 Normal 47 74 24 145 29.2+/-3.93 Dwarf 2 16 16 34 Total 49 90 40 179 ________________________________________________________________ d-33 Pox-2 Total p(%) 4C 0 ________________________________________________________________ Normal 138 7 145 7.6+/-2.07 Dwarf 5 29 34 Total 143 36 179 ________________________________________________________________
-Acp-1.
Third, a line derived from T65 X W120 carrying Pgd-23, Est-23 and Pgi-21 was crossed with IR36 which had Pgd-21, Est-22 and Pgi-22. The F2 population showed that these three loci are linked and all belong to linkage group I. Their recombination values were estimated (Table 2). Pgd-2 seemed to be located between wx and Est-2 (Fig. 2).
Table 2. Linkage relations and recombination values (p) obtained in the cross between an F4 line derived from Taichung 65 X W120 (wild) carrying Pgd-23, Pgi-21 and Est-23 and IR36 carrying Pgd-21, Pgi-22 and Est-22
a) Pgi-2 with Pgd-2 and Est-2 ________________________________________________________________ Pgi-2 Gene linked 2/2 2/1 1/1 Total p (%) ________________________________________________________________ Pgd-2 1/1 3 7 2 12 1/3 4 15 1 20 30.8+/-6.62 3/3 0 8 7 15 Est-2 2/2 6 4 0 10 2/3 1 22 2 25 12.7+/-3.43 3/3 0 4 8 12 Total 7 30 10 47 ________________________________________________________________ b)Between Pgd-2 and Est-2 ________________________________________________________________ Pgd-2 Gene linked 1/1 1/3 3/3 Total p(%) ________________________________________________________________ Est-2 2/2 4 5 1 10 2/3 7 14 4 25 25.5+/-5.40 3/3 1 1 10 12 Total 12 20 15 47 ________________________________________________________________
References
Ishikawa, R., T. Kinoshita and H. Morishima, 1988. Linkage analysis of the Pgd-1 locus. RGN 5: 81-82.
____, H.Morishima, K. Mori and T. Kinoshita, 1989. Chromosomal analysis of isozyme loci and the allelic expression at cellular level in rice. Genetical studies on rice plant, 97.J. Fac. Agr. Hokkaido Univ. 64: 85-98.
Pai, C., T. Endo and H,.I. Oka, 1975. Genic analysis for acid phosphatase isozymes in Oryza perennis and O. sativa. Can. J. Genet. Cytol. 17: 637-650.
Ranjhan, S., J. C. Glaszmann, D. A. Ramirez and G. S. Khush, 1988. Chromosomal localization of four isozyme loci by trisomic analysis in rice (0ryza sativa L.). Theor. Appl. Genet. 75: 541-545.
Wu, K. S., J. C. Glaszmann and G. S. Khush, 1988. Chromosomal locations of ten isozyme loci in rice (Oryza sativa L.) through trisomic analysis. Biochem. Genet. 26: 303-320.