36. Allelic relation between photoperiod-sensitive genic male-sterility and cy-
        toplasmic-genic male sterility of BT type in rice

            You Shao and Xi-Hua Tang
            Shanghai Institute of Plant Physiology, Academia Sinica, 300 Fonglin Road, Shanghai, 200032 China

    Photoperiod-sensitive sterility is controlled by two independent recessive genes, and their restorer genes are found not only in Japonica but also in Indica and Javanica or tropical Japonica varieties (Shao and Tang 1992). The F2 between sterile and restorer varieties showed a segregation ratio of 15 fertile: 1 sterile, and the B1F1 with sterile varieties segregated into 3 fertile : 1 sterile types. In another case, the F1 gave a 3: 1 ratio as the restorer parent carried a restorer gene and a sterility gene (Shao et al. 1993).
    We have crossed a cytoplasmic male-sterile strain of the "BT" type having an Indica cytoplasm, Hen-Feng A (used as mother parent) with a photoperiod-senstive male-sterile strain (PGMS), Nong-Ken 58S in 1991. The F1 plants were sterile under both short-day and long-day conditions. The F2 segregated into 15 fertile : 1 sterile types, suggesting that Nong-Ken 58S has duplicate sterility gene. With the hope of examining the allelic relation between these two kinds of sterility, we tested the hybrid plants in a phytotron adjusted at 25° ± 1° constant with daylength of 14.5h and 12h.
    The materials tested were: Hen-Feng A, a BT-type male-sterile strain derived from an Inidca-Japonica cross having the Indica cytoplasm, and Liu-Zie-Xin A with their respective maintainers Hen-Feng B and Liu-Zie-Xin B; and a photoperiod-sensitive male-sterile strain Nong-Ken 58S with its derivatives, C407S, 7001 S, N5047S, 3111S, and 8912S.
    All these strains were nearly completely sterile except for Nong-Ken 58S under the short-day (Table la). The F1 plants of Liu-Zie-Xin A or Hen-Feng A with Nong-Ken 58S and its derivatives were largely sterile when tested under the short-day condition (Table lb). The B1F1 plants from Hen-Feng A/Nong-Ken 58S// Hen-Feng B were sterile under both short-day and long-day conditions. In contrast, the F1 plants of Nong-Ken 58S X
 
 

Table 1. Percent seed setting observed in photoperiod-sensitive male-sterile strains (PGNS), cytoplasmic plants male-sterile strains of BT type, and their F1,plants
                                                         Shortday (12h) Longday (14.5h)
Strain & cross No. of plants Mean±S.D. No. of 
plants		 Mean± S.D.
%
a) Nong-Ken 58S 10 72 ±6.3 13  0.2±0.4
Liu-Zie-Xin A 6 0 3  0
Hen-Feng A 
F1: (Liu-Zie-Xin A/ Nong-Ken 58S)
F1: (Hen-Feng A/ Nong-Ken 58S)		 7

8 

25

 0.1±0.3 

0 

1.1±1.9

 4 

6

 0
0
b) F1 of derivative from Nong-Ken 58S (shortday only)
Liu-Zie-Xin A/7001S 10 0
Liu-Zie-Xin A/3 IIIS 7 1.5±2.6
Hen-Feng A/7001S 
Hen-Feng A/C407S 
Hen-Feng A/N5047S 
Hen-Feng A/8912S 
Nong-Ken 58S		 10 
9 
7 
7 
7		 4.7±2.4 
4.0± 1.9
0.8±1.7 2.7±4.3 
80 ±3.4
c) Triple cross & maintainer cross 
Hen-Feng A/Nong-Ken 58S// 
Hen-Feng B 
Nong-Ken 58S/Hen-Feng B		 5 

8

 4.0±2.3 

52 ±7.1

 4

7

 0.9±1.1
6.5±6.6

Hen-Feng B were fertile (Table 1 c).

    It may be concluded from these data that one of two sterility genes of Nong-Ken 58S is allelic with the
sterility gene of Hen-Feng A.

References

Shao, Y. and X. H. Tang, 1992. Analysis of restorer genes for photoperiod-sensitive male-sterile rice. RGN 9:
        52-54.
Shao, Y., X. H. Tang and Q. L. Huang, 1993. Studies on the sterile genes and its restorer genes in
        photoperiod-sensitive male-sterile rice. Acta Agriculturae Shanghai 9(3): 22-29.