1) Institute of Genetic Resources, Faculty of Agriculture,
Kyushu University, Hakozaki, Fukuoka,
812 Japan.
2) Plant Breeding and Genetics Research Laboratory,
Japan Tabacco Inc., lwata, Shizuoka, 438 Japan.
3) Yamaguchi Women's University, Sakurabatake, Yamaguchi,
753 Japan.
4) Oh-lta Agricultural Experimental Station, Usa,
Oh-lta, 872-01 Japan.
5) Seoul Women's University, Seoul, 139-744 Korea.
Some of mutants for the 57H character, which have
a high accumulation of 57 kD polypeptides of rice storage proteins, were
induced by an MNU treatment of rice (Kumamaru et al. 1988). So far
three loci, esp-2, Glup-l (Gup-1) and glup-2 (gup-2), have
been identified for the 57H mutation in rice, and have been located on
chromosome 11, 9 and 9, respectively (Kumamaru et al. 1987; Satoh
et
al. 1994). We found that 57H mutants occurred spontaneously in rice
accessions which were introduced from North Asian countries in 1930s and
preserved in Kyushu University. The spontaneous 57H mutants were characterized
by the remarkably increased content of 57 kDa polypeptide with the markedly
decreased content of 40 kDa (glutelin acidic subunit) and 20 kDa (glutelin
basic subunits) polypeptides in the SDS-PAGE. Nineteen 57 H mutant strains
were so far observed in 1400 accessions, from Russia, Northern China and
North Korea. The phenotype of these spontaneous 57 H mutants were very
similar to each other.
Seven 57H mutant were reciprocally crossed with
normal cultivars, Kinmaze and T65. The phenotype of F1s was
normal and the segregation of normal and mutant types in F2s
showed a good fit to a 3:1 ratio. These results indicated that the spontaneous
57H mutants are due to single recessive genes. Nineteen mutants were crossed
with each other, The phenotypes of F1S were 57H type in all
of the cross combinations, and no segregation of normal type in the F2
s was found and all of the F2 seeds derived from these cross
combinations showed the mutant phenotype. These results show that the spontaneous
57H mutants were due to allelic genes.
Some of the spontaneous mutant strains were crossed
reciprocally with three marker lines, CM1787 for esp-2, EM61 for
Glup-l
and EM305 for glup-2. Table 1 shows the phenotype of F1
seeds and the segregation patterns in F2 seeds derived from
crosses of a spontaneous 57H mutant strain, H01055, with CM1787, EM61 and
EM305. The F1 seeds from the cross between H01055 and CM1787
showed the normal phenotype, and F2 seeds were classified
into normal, CM1787 and H01055 type. Since the double mutant phenotype
was not able to distinguish from the CM1787 type except for a few cases,
segregation of these three types fitted the expected ratio of 9:4:3. These
results suggested that 57-H mutant gene of H01055 is not allelic to esp-2
of CM1787, and that esp-2 and the 57-H mutant gene of H01055 show
the additive effect on the accumulation of 57 kD polypeptides.
F1 seeds from the cross between EM61
and H01055 showed the mutant phenotype of EM61, and F2 seeds
were classified into normal, EM61 and H01055. Since the double
Table 1. Segregation pattern of 57-H character in F1 seeds
of crosses between a
spontaneous 57H mutant,
H01055, and three marker lines for 57-H gene,
CM 1787, EM61 and EM305
Cross combination | F1 seed | Segregation in F2 | X2 | |||
Normal | H01055 | CM1787 | Total | (9:4:3) | ||
H01055 X CM1787 | Normal | |||||
112 | 45 | 37 | 194 | 0.35 | ||
Normal | H01055 | EM61 | Total | (3:4:9) | ||
HO 1055 X EM61 | 57-H | |||||
46 | 53 | 100 | 199 | 3.51 | ||
Normal | H01055 | EM305 | Total | (9:4:3) | ||
HOI 055 X EM305 | Normal | |||||
89 | 42 | 27 | 158 | x^2 |
mutant phenotype was not able to distinguish from the H01055 type, segregation
of these types fitted the expected ratio of 3:4:9. These resullts suggested
that 57-H mutant gene of H01055 is not allelic to Glup-l of EM61.
The F1 seeds of the cross between H01055 and EM305, were normal
for the 57-H character, and the F2 seeds were classified into
normal, EM305 and H01055 types. As the doubly recessive type could not
be identified from the 57-H mutant type of H01055 though some of them showed
the double mutant phenotype, the segregation fitted the expected 9:3:4
ratio, indicating that the 57-H mutant locus of H01055 is different from
glup-2.
The same results were obtained in the cross combinations between the other
spontaneous 57H mutant strains and the three marker lines.
Furthermore, trisomic analysis of a spontaneous
57-H mutant, H01055, revealed that segregation of F2 seeds between
the mutant and trisomic E plant fitted to the trisomic segregation ratio
(Table 2). The new mutant gene of H01055 is designated as glup-3(t)
(glutelin precursor mutant-3(t)) and that the gene is located on chromosome
4.
Table2. Segregation
of normaland 57-H in F2 seeds set onTriplo
F1 plants derived from the crosses between and a spontaneous 57H mutant, H01055 |
||||
Type of Trisomics | Segregation in F2 | X2 (1:3) | ||
Normal | 57-H | Total | ||
Triplo 4 | 177 | 23 | 200 | 19.44** |
Triplo 5 | 31 | 9 | 40 | 0.13 |
Triplo 6 | 151 | 49 | 200 | 0.03 |
Triplo 7 | 31 | 5 | 36 | 2.37 |
Triplo 8 | 29 | 8 | 37 | 0.23 |
Triplo 9 | 29 | 10 | 39 | 0.01 |
Triplo 10 | 31 | 8 | 39 | 0.42 |
Triplo 11 | 88 | 32 | 120 | 0.18 |
Triplo 12 | 30 | 9 | 39 | 0.08 |
References
Kumamaru, T., H. Satoh, N. Iwata, T. Omura and M. Ogawa, 1987. Mutant
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.
Kumamaru, T., H. Satoh, N. Iwata, T. Omura, M. Ogawa and K. Tanaka,
1988. Mutants
for rice storage proteins. I. Screening of mutants
for storage proteins of protein bodies in the
starchy endosperm. Theor. Appl. Genet. 76:11-16.
Satoh, H., T. Kumamaru, S. Yoshimura and M. Ogawa, 1994. New 57 kDa
glutelin genes on
chromosome 9 in rice. Rice Genet. Newsl. 11:
158-161.