26. Genic analysis for isozymes in rice


Hiroko MORISHIMA and Reiko SANO

National Institute of Genetics, Misima, 411 Japan


Isozyme analysis in rice was pioneered by Chu (1967) and was extended to a wide range of materials by several workers as reviewed by Endo and Morishima (1983). Generally, wild species are more variable than cultivated species. So far, 14 enzyme species were studied and 40 loci were proposed (Second 1982). However, formal genic analysis was limited to some 12 loci. The 9 loci which were identified by deliberate crossing experiments by using the starch gel system are listed in Table 1. For the techniques employed, the reader is referred to Pai et al. (1973, 1975) and Second and Trouslot (1980). In addition, 4 loci encoding esterase were detected on acrylamide gels by Nakagahra (1977).

Each allele at the 9 loci listed specifies a single band, except for Acp-1 alleles each specifying a set of three major and three minor bands. An inter-locus hybrid band is formed between Pgi-1 and Pgi-2. Pgi-1 and Est-2 were linked (13% recombination) with each other and with wx (35% and 22% recombination, respectively); they were thus located on chromosome 6. In addition, temperature sensitive variants were detected for certain loci (Second 1982). Furthermore, the presence of regulatory genes was proposed to interpret organ specificity and temporal patterns of isozyme activity (Pai et al. 1973; Endo 1981a,b).


Table 1. Data for isozyme genes identified by formal genic analysis


=============================================================================
Enzyme      Symbola    Type    No. of  Null  Linkage with:    Reference
                              alleles  form
=============================================================================
Acid phos-    Acp-1    dimer     8  Present  Pox-2 (31-34%)  Pai et al.(1975)
     phatase                                                 Pai &  Fu (1977)
              Acp-2    monomer   3    "      Acp-1           Pai et al.(1975)
              Acp-3    monomer   2    "
Peroxidase    Pox-1    dimer     4    "                      Pai et al.(1973)
                                                             Pai &  Fu (1977)
              Pox-2    monomer   2    "      Acp-1 (31-34%)  Pai et al.(1973)
Catalase      Cat-1    tetramer  2  Unknown                Second & Morishima
                                                             (1980)
Phospho-      Pgi-1    dimer     4    "                          "b  
  glucose
  isomerase   Pgi-2    dimer     4    "      Est-2 (13%)         "b  
                                             wx(35%)
Esterase      Est-2    monomer   3  Present  Pgi-2 (13%)     Authors' unpubi.
                                             wx (25%)          data
=============================================================================
a.  Px-1 and Px-2 in original papers are symboled Pox-1 and Pox-2; Cat-A,
Pgi-A and Pgi-B in original papers are symboled Cat-1, Pgi-1 and Pgi-2,
respectively.
b.  Partly due to authors' unpublished data.

References

Chu, Y. E., 1967. Variations in peroxidase of Oryza perennis and O. sativa. Jpn. J. Genet. 42:233-244.

Endo, T., 1981a. Developmental modification and hybridization of allelic acid phosphatase isozymes in homo- and heterozygotes for the Acp-1 locus in rice. Biochem. Genet. 19: 373-384.

------, 1981b. Differential regulation of peroxidase isozymes coded by Px-1 locus in rice. Jpn. J, Genet. 56: 175-183.

Endo, T. and H. Morishima, 1983. Rice. In S. D. Tanksley and T.J. Orton (eds.), Isozymes in Plant Genetics and Breeding, Part B, pp. 129-146. Elsevier, Amsterdam.

Nakagahra, M., 1977. Genic analysis for esterase isoenzymes in rice cultivars. Jpn. J. Breed. 27: 141-148.

Pai, C., T. Endo and H. I. Oka, 1973. Genic analysis for peroxidase isozymes and their organ specificity in Oryza perennis and O. sativa. Can. J. Genet. Cytol. 25: 845-853.

-----, ----- and -----, 1975. Genic analysis for acid phosphatase isozymes in Oryza perennis and O. sativa. Can. J. Genet. Cytol. 17: 637-650.

----- and P. Y. Fu, 1977. Genetic analysis for peroxidase and acid phosphatase isozymes in cultivated rice. Argon. Bull., Nat. Chung Hsing Univ., Taichung, No. 2: 75-85 (Chinese with English summary).

Second, G., 1982. Origin of the genic diversity of cultivated rice (Oryza spp.): Study of the polymorphism scored at 40 isozyme loci. Jpn. J. Genet. 57: 25-75.

----- and H. Morishima, 1980. Mendelian segregation analysis for three isozyme loci in rice cultivars. Ann. Rep. Nat. Inst. Genet., Japan 31: 117-118.

----- and P. Trouslot, 1980. Electrophorese d'Enzymes de Riz (Oryza sp.). Travaux et Documents de l'ORSTOM, Paris, No. 120. 88pp.