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Shanghai Institute of Plant Physiology, Acad. Sinica, Fonlin Road, Shanghai, 200032, China
Segregation for fertility was observed in 1990-1991 under long-day conditions in F2 (18 cross combinations) and B1F1 (3 cross combinations) of photoperiod sensitive male-sterile Japonica lines, Nongken 58s and its derivatives, i.e., C407s (early maturing), WD1s, 7001s, N5047s, and 3111s (late maturing). The pollen parents were Japonicas (Current 422; Hanfeng; Xianzhen; 77302; 4402; restorer 41, 45, and 261) and derivatives from Indica-Japonica hybrids (CPLSO-17; 02428; DT713-1; and DT713-3).
The pattern of F2 fertility variations in six Japonica crosses with Nonkeng 58s showed a good agreement with 15 fertile: 1 sterile ratios (Table 1). This suggests the presence of two independent recessive genes, ms\1\p and ms\2\p for the sterility of Nongken 58s. When both exist in homozygous combination, the carrier shows sterility under a long-day condition. The restorers would have dominant alleles, Ms\1\p and Ms\2\p. Reciprocal crosses showed the same pattern indicating that no cytoplasmic effect was involved. Ten F2 populations from crosses of other strains also showed the 1 sterile: 15 fertile segregation (Table 2). Two F2 populations, 7001s X 45 and 31111s X 261 showed a 1 sterile : 3 fertile ratio, suggesting
Table 1. Segregation for fertility in F2 populations from crosses between
Nongken58s and Japonica restorers (1990)
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Cross combination Sterile Fertile Total X2 P
plants plants no. (1:15)
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Nongken58s/77302 45 705 750 0.04 >0.5
Nongken58s/4402 44 655 699 0.002 >0.9
Nongken58s/R41 29 459 488 0.03 >O.75
Nongken58s/Xianzhen 9 100 109 0.45 >0.5
Nongken58s/Hanfeng 12 261 273 1.30 >0.25
Hanfeng/Nongken58s 15 144 159 2.24 >O.1
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Table 2. Fertility segregation in F2 and B1F1 populations (1991)
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Cross combination Sterile Fertile Total Ratio X2 P
plants plants no. exp.
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F2 C407s/DT713-1 18 218 236 1:15 0.55 >0.25
F2 WD1s/Lunhui422 19 216 235 1:15 1.06 >0.25
F2 7OO1s/CPLS017 16 232 248 1:15 0.02 >0.9
F2 7OO1s/Xianzhen 20 254 274 1:15 0.35 >0.5
F2 7OO1s/DT713-3 11 158 169 1:15 0.04 >0.75
F2 7OO1s/DT713-1 32 448 480 1:15 0.08 >0.75
F2 7001s/02428 2 272 297 1:15 2.11 >O.1
F2 N5047s/02428 28 301 329 1:15 2.50 >O.1
F2 7001 s/45 23 95 118 1:3 1.63 >O.1
F2 31111s/261 46 184 230 1:3 2.81 >0.05
B1F1 WD1s//WD1s/Lunhui422 4 8 12 1:3 0.11 >0.5
B1F1 7OO1s//70O1s/CPLS017 8 28 36 1:3 0.04 >0.75
B1F1 7OO1s//7001s/Xianzhen 4 15 19 1:3 0.02 >0.9
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Table 3. F2 distribution of seed-setting rate in sterile (S) and fertile (F)
plant groups
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Fertility Seed setting rate (%) Total
Cross group =========================================
0 10 20 30 40 50 60 70 80 90 >95 no.
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Nongken58s/77302 S 8 3 11
F 1 2 3 20 50 55 74 14 219
Nongken58s/4402 S 1 2 3
F 1 2 9 17 19 39 14 101
C407s/DT713-1 S 16 2 18
F 11 5 34 57 48 31 19 11 1 218
WD1s/Lunhui422 S 11 6 2 19
F 7 11 14 21 44 49 34 34 2 216
7OO1s/CPLS017 S 8 7 1 16
F 3 13 11 20 21 25 28 40 54 17 232
7OO1s/Xianzhen S 3 6 7 3 1 20
F 1 1 6 15 22 35 33 69 67 5 254
7001s/DT713-3 S 1 2 7 11
F 1 6 14 20 43 42 26 6 158
7001s/DT713-1 S 25 1 26
F 18 21 25 55 49 52 39 19 7 285
7001s/02428 S 8 16 1 25
F 5 7 13 21 23 42 58 53 39 11 272
N5047s/02428 S 16 11 1 28
F 2 1 4 12 13 16 26 37 65 88 37 301
31111s/261 S 14 28 3 1 46
F 7 7 5 7 3 6 27 38 68 16 184
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that strains 45 and 261 have either Ms\1\p MS\2\p or ms\1\p MS\2\p.
Nongken 58s X Nongken 58 also gave a 1 sterile: 3 fertile segregation (Shi
and Den 1986; Zhu and Yu 1987).
The B1F1 plants using the male-sterile plants as recurrent parent showed 1 sterile: 3 fertile ratios (Table 2). This confirms that the male-sterility is controlled by two independent recessive genes in both the Japonica and Indica types.
The F2 distributions of seed-setting rate showed a high peak of frequency in fertile plant-group and a lower peak in sterile group (Table 3). This agrees with the expectation from two pairs of recessive genes assumed. In some crosses, the valley between the sterile and fertile groups clearly showed the boundary of the two groups, but other crosses did not. No data were obtained to support the hypothesis of incomplete dominance of the restorer genes as proposed by Xue and Dong (1991).
References
Shi, M. B. and J. Y. Deng, 1986. Hubei photoperiod-sensitive genic male-sterile rice: Its discover, identification and utilization. Acta Genetica Sinica 13(2): 107-112.
Xue, G. X. and J. Y. Deng, 1991. Studies on the Hubei photoperiod-sensitive nuclear male-sterile rice (Oryza sativa L. subsp. Japonica). Acta Genetica Sinica 18(t): 59-66.
Zhu, Y. G. and J. H. Yu, 1987. The studies on stability and genetic behavior of HPGMR. J. Wuhan Univ. (Natural Sci. Edition; Special Issue), p. 61-67.
