Fig. 2. Diagramatic patterns of segregating types for spikelet fertility in selfing generations. The letter in the frame shows the fertility type in the following selfed progeny.
A case of female sterility was found in the cross between an Indonesian variety
Tjina and a Japanese variety Fujisaka 5. The F\1\ of Fujisaka 5XTjina was
backcrossed with Fujisaka 5 recurrently. Plant with a very low spikelet
fertility were found in the selfed progeny of the fourth backcross. The
spiklets of sterile plants flowered normally and had a high pollen fertility.
The emasculated spikelets of Fujisaka 5 pollinated with the pollen grains of
the sterile plants gave a high seed set, but the emasculated spikelets of the
sterile plants pollinated by Fujisaka 5 set no seed. The embryosacs of the
sterile plants had no normal structure (Fig. 1 A missing embryo-sac in the
highly sterile plants/Fujisaka 5 formed a normal embryo-sac.). Genic analysis
revealed that this female sterility was controlled by two recessive genes (Fig.
2 Diagramatic patterns of segregating types for spikelet fertility in selfing
generations.).
The female sterile plants produced a few seeds per panicle, so that they could be maintained as homozygote. The female-sterility genes seem to have an incomplete penetrance. The seeds of the sterile line obtained from an additional backcross are maintained at the Germplasm Storage Center, National Institute of Agrobiological Resources, with a code "FUJISAKA 5 (FEMALE STERILITY)"
Fig. 1. A missing embryo-sac in the highly sterile plants (below). Fujisaka 5
formed a normal embryo-sac (above).
Fig. 2. Diagramatic patterns of segregating types for spikelet fertility in
selfing generations. The letter in the frame shows the fertility type in the
following selfed progeny.
Reference
Yokoo, M., 1984. Female sterility in an Indica-Japonica cross of rice. Jpn. J. Breed. 34: 219-227. (in Jap. with Eng. summary)