43. A temperature-sensitive dwarf mutant showing haploid-like featurs in rice

Itsuro Takamure and Toshiro Kinoshita

Plant Breeding institute, Faculty of Agriculture, Hokkaido University, Sappro, 060 Japan


Several temperature-sensitive dwarf mutants have been reported in rice (Kitano and Futsuhara 1981, 1982; Takamure and Kinoshita 1985). Recently, a mutant line N-172 was induced which showed haploid-like features characterized by short and fine culms, small spikelets and complete sterility when grown in the paddy field. It was found as a segregant in the progeny of AC-85 (an inbred line produced from anther culture) irradiated with chronic gamma-rays (430 R/day during the growing period). When grown in greenhouse, the mutant line regained nearly normal features and set some seeds, although fertility was low. Therefore,it may be regarded as temperature sensitive, expressing the haploid- like feature in response to low temperatures in the field (Table 1).

To learn about the genetic basis, the mutant line was crossed with a multiple marker stock, H-79. The F\1\ plants showed normal characters and complete fertility.

The F\2\ populations segregated into 3 normal : 1 haploid-like (1199:365) although a deficiency of haploid-like plants was found in two of 10 F\2\ populations observed. This suggests that the mutant line possesses a single recessive temperature-sensitive dwarfing gene, which is denoted d-58(t).


Table 1. Comparison of 12 characteristics between AC-85 and N-172 grown under two different conditions

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Character                    Line           Paddy Field            Greenhouse
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Culm lenght (cm)             AC-85            86.6                   68.0
                             N-172            33.0**                 62.5
1st internode length (cm)    AC-85            30.6                   24.5
                             N-172             7.3**                 21.9
2nd internode length (cm)    AC-85            25.1                   20.1
                             N-172            11.1**                 17.6
3rd internode length (cm)    AC-85            22.3                   14.8
                             N-172             7.7**                 12.5
4th internode length (cm)    AC-85            10.1                    7.7
                             N-172             6.3**                  7.9
5th internode lenght (cm)    AC-85             1.5                    0.9
                             N-172             0.6                    2.6
Panicle length (cm)          AC-85            17.5                   14.9
                             N-172             8.3**                 12.9*
No. of panicles              AC-85             7.3                    4.3
                             N-172             7.5                    7.5
No. of spikelets             AC-85           157.8                   97.8
                             N-172            42.8**                 89.8
Seed sterility (%)           AC-85            11.1                   77.6
                             N-172           100.0**                 97.5**
grain length (mm)            AC-85             5.73                   5.49
                             N-172             4.20**                 5.29
Grain width (mm)             AC-85             3.72                   3.69
                             N-172             2.38**                 3.31**
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*,** Significantly different from the original line at the 5 and 1% levels, respectively



References

Kitano, H. and Y. Futsuhara, 1981. Character expression of induced dwarf mutants in rice. I. Effects of temperature on culm elongation in the dwarf mutant line Fukei No. 71. Jpn. J. Breed. 31: 9-18.

Kitano, H. and Y. Futsuhara, 1982. Character expression of induced dwarf mutants in rice. II. Morphological and histological observations on the effects of temperature on culm elongation in the dwarf mutant, Fuhei No. 71. Jpn. J. Breed. 32: 146-154.

Takamure, I. and T. Kinoshita, 1985. Inheritance and expression of reduced culm number character in rice. Jpn. J. Breed. 35: 17-24.