20. Gene for the "naked-grain rice"

Ruey-Min Hsieh1, Chiang Pai1 and Hsin-Kan Wu2

1) Food Crops Research Institute, National Chung Hsing University, Taichung, Taiwan 400;

2) Institute of Botany, Academia Sinica, Nankang, Taipei, Taiwan 115, China

The seed of "naked-grain rice" was made available through the courtesy of Dr. T.T. Chang (IRRI), which was isolated as a derivative of a "rice x wheat hybrid" in Fujian, China. Cytological examination showed that the plants had exactly the same karyotype as of ordinary rice cultivars, and that their peroxidase and acid phosphatase zymograms were the same as those found in ordinary Indica cultivars. There was no evidence of any genetic material having been introduced from wheat. When the naked-grain rice was crossed with 11 rice cultivars, all data for the F1 and F2 progenies proved that it was controlled by a single recessive gene. The gene affected the development of young panicles at the stage of spikelet differentiation, resulting in modification of floral morphology such as the elongation of paleas to have a leaflet-like structure, malformation of pistil, stigma and other floral organis, redifferentiation of florets from the pedicle, and a low seed setting rate. These phenotypes are similar to those of the "long-hull sterile" mutant (Kinoshita et al. 1977), which is controlled by lhs-2 belonging to linkage group XII. When the naked-grain rice was crossed with the long-hull sterile strain, the F1 plants showed the floral characters of the both parents. This indicates that the gene for the Chinese naked-grain rice is allelic to lhs-2.

Reference

Kinoshita, T., Y. Hidano, and M. Takahashi, 1977. A mutant 'long hull sterile' found in the rice variety, Sorachi. Mem. Fac. Agr. Hokkaido Univ. 10(3): 247- 268.