74 Rice Genetics Newsletter Vol. 14
23. Male sterile mutants induced through irradiation of egg cells in rice
P. plaha, G.S. khush and D.S. brar
International Rice Research Institute, P. 0. Box 933. 1099 Manila, Philippines
Cytoplasmic-genetic male sterility system has been commercially exploited for the production of F1 hybrids in a number of crop plants. More recently, major progress has been made in developing high yielding hybrid rice varieties using CMS based on wild abortive (WA) cytoplasm. However, due to some inherent limitations of CMS, breeders are exploring the possibilities to use TGMS (thermo-genic male sterility) and PGMS (photoperiod genic male sterility) to develop two-line rice hybrids (Virmani 1996). In this communication, we report the isolation of male sterile mutants in rice by irradiating egg cells with gamma-rays.
Panicles of cultivar IR36 were emasculated and subsequently irradiated with 7.5kR
gamma-rays followed by pollination with a dominant purple leaf rice as marker. A total
Table 1 |
. Segregation progenies in the |
pattern of male sterile MJ^ generation |
|
Progeny |
no. Fertile plants |
Sterile plants fl |
|
2U/'Bfa 20783 |
26 24 |
•1 9 |
0.253 0.091 |
20915 |
25 |
9 |
0.039 |
20919 |
28 |
6 |
0.980 |
21099 |
27 |
6 |
0.818 |
21201 |
30 |
8 |
0.316 |
21309 |
30 |
8 |
0.316 |
21588 |
25 |
8 |
0.010 |
21827 |
25 |
8 |
0.010 |
22079 |
27 |
7 |
0.353 |
22234 |
29 |
6 |
1.152 |
22305 |
27 |
7 |
0.353 |
22313 |
27 |
7 |
0.353 |
22661 |
26 |
8 |
0.039 |
22662 |
28 |
6 |
0.980 |
22663 |
26 |
8 |
0.039 |
23009 |
26 |
7 |
0.253 |
23118 |
26 |
4 |
2.178 |
23383 |
15 |
5 |
0.000 |
23386 |
26 |
7 |
0.253 |
23393 |
20 |
4 |
0.889 |
23424 |
0 |
4 |
12.000 |
23459 |
20 |
10 |
1.111 |
23470 |
12 |
4 |
0.000 |
23474 |
17 |
6 |
0.014 |
23486 |
12 |
4 |
0.000 |
23546 |
0 |
5 |
15.000 |
23662 |
26 |
5 |
1.301 |
23673 |
19 |
5 |
0.222 |
23704 |
0 |
3 |
9.000 |
23872 |
15 |
5 |
0.000 |
23995 |
0 |
1 |
3.000 |
24221 |
19 |
4 |
0.710 |
Research Notes 75
of about 12,000 M1F1 seeds were produced from which 5,150 M1F1 plants were obtained. These M1F1 plants were harvested individually and plant-to-row M2F2 progenies were raised.
At flowering, progenies were visually scored for segregation for male sterility and fertility. Pollen sterility in each segregating progeny was examined by staining pollen with 1.0% IKI. Plants with less than 10% pollen stainability were considered as male sterile and those with more than 60% as fertile. At maturity the behaviour of the progenies was reconfirmed on the basis of seed set. The sterile plants of the progenies either did not set any seed or set only a few seeds. Of the 5,150 progenies, 29 (0.55%) were found to segregate for male sterility (Table 1). In each of these progenies, male sterility was found to be governed by a single recessive gene. Four progenies (23424, 23546, 23704, 23995) had a few but only sterile plants. The fewer number of plants is due to rare seed set in the respective M1F1 plants. These four progenies could be CMS. All male sterile progenies are under investigation to determine the nature of male sterility.
Vimiani,S.S.,1996. Hybrid rice. Adv.Agron. 57:377-462.