Institute for Agricultural Biology, Okayama University, Kurashiki, 710 Japan
A spontaneous mutant with open-hull male sterility was found in an experimental line (Fig. 1). The mutant was characterised also by lower seed fertility,
Table 1. Segregation of the 'open hull male sterile' mutant in
F2 populations
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Number of plants
Sample ____________________________________ X2 (3: 1)
Normal Mutant Total
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1 88 28 116 0.05
2 96 25 121 1.22
3 112 20 132 6.83**
4 82 28 110 0.01
5 73 14 87 3.68
6 84 26 110 0.11
7 69 13 82 3.66
8 91 23 114 1.42
Total 695 177 872 10.28**
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**Significant at the 1% level.
Heterogeneity: X2 = 6.70(df = 7),P=0.3-0.5.
smaller caryopsis, darker leaf color, and remarkable ratooning. The anthers
of the mutant were white and small, without viable pollen. No seed was
developed in the panicles when bagged before anthesis. Spikelet fertility of
naturally open- pollinated panicles was 5-20%. All the plants derived from
the seeds set on the mutant were phenotypically normal, suggesting that the
seeds were produced by cross pollination with normal plants.F2 segregation indicated that this mutant was controlled by a single recessive gene, although the observed number of mutants was somewhat smaller than expected (Table 1). As this mutant is distinguishable from other open-hull mutants (RGN 1, p. 40) by its male sterility, the new gene may be named oms (open-hull male sterile).