26. Location of a mutant gene for rice storage protein esp-3 on Nishimura's chromosome 9

T. KUMAMARU1,3, H. SATOH2, T. OMURA3 and M. OGAWA4

1) Plant Breeding and Genetics Research Laboratory, Japan Tabacco Inc. 700 Higashibara, Iwata, Shizuoka-ken, 438 Japan

2) Institute of Genetic Resources, Faculty of Agriculture, Kyushu University, Hakozaki, Fukuoka, 812 Japan

3) Plant Breeding Laboratory, Faculty of Agriculture, Kyushu University, Hakozaki, Fukuoka, 812 Japan

4) Research Institute for Food Science, Kyoto University, Uji, Kyoto, 611 Japan

Rice storage protein exists in two types of protein bodies, PB-I and PB-II. The former is indigestible, while the latter is digestible. Hence, for improving the nutritional value of rice grain, it would be desirable to increase PB-II content and to decrease PB-I. In SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) analysis, PB-I showed 10 kDa, 13a, 13b and 16 kDa polypeptides, and PB-II showed 22-23 kDa., 26 kDa and 37-39 kDa polypeptides. Formerly, we screened different mutant types of storage proteins (Kumamaru et al. 1988), and reported that gene esp-1 for 13b-L and esp-2 for 57-H were located on Nishimura's chromosomes 10 and 9, respectively (Kumamaru et al. 1987). Gene esp-3 for 10/13a-L appeared to be inherited maternally. We carried out trisomic analysis to determine the chromosome on which esp-3 was located.

Line CM1675 carrying this gene was crossed with trisomic types A, C, D, E, G and L. The F1 plants were classified into disomic and trisomic types according to Iwata et al. (1970), and the F3 seeds were harvested separately from disomic

Table 1. Segregation of normal and 10/13a-L protein types in F2
       plants from crosses between certain trisomics and CM1675
_______________________________________________________________
Trisomic Nishimura's F2 plant    F2 segregation           X2  
  type   chromosome  type     ____________________       (3:1)
                              Normal 1O/13a-L Total
________________________________________________________________
G            9     2n+1 & 2n   174       11    185     35.8***
A            4     2n+1         29        9     38        0.04
C            7     2n+1         31        7     38        0.9
D           12     2n+1         31        7     38        0.9
E           11     2n+1         32        6     38        1.7
L            2     2n+1         36        8     44        1.1
________________________________________________________________
*** Significant at 0.1% level.
and trisoniic F2 plants derived from the trisomic F1 plant. In the cross with trisomic G, however, the F2 plants could not be divided into disomic and trisomic types clearly and their F3 seeds were harvested without distinction. The F3 seeds from each F2 plant were analyzed by SDS-PAGE (Table 1). In the cross with trisomic type G, the F2 ratio for normal and 1O/13a-L types was about 16: 1, fitting the trisomic ratio which could range between 8: 1 and 44: 1. Crosses with other trisomic types all showed a 3: 1 ratio (Table 1).

References

Iwata, N., T. Omura and M. Nakagahra, 1970. Studies of the trisomics in rice plants, 1. Morphological classification of trisomics. Jpn. J. Breed. 20: 230-236.

____, ____, 1975. Studies on the trisomics in rice plants, III. Relation between trisomics and genetic linkage groups. Jpn. J. Breed. 25: 363-368.

Kumamaru, T., H. Satoh, N. lwata, T. Omura and M. Ogawal 1987. Mutants for rice storage proteins, III. Genetic analysis of mutants for storage proteins of protein bodies in the starchy endosperm. Jpn. J. Genet. 62: 333-339.

____, ____, ____, ____, ____,and K. Tanaka, 1988. Mutants for rice storage proteins of protein bodies in the starchy endosperm. Theor. Appl. Genet. 76: 11-16.