18. Character expressions of various dwarfing genes at haploid level

1)Plant Breeding Institute, Faculty of Agriculture, Hokkaido University, Sapporo, 060 Japan;

A series of haploid dwarf isogenic lines were produced by another culture from 19 diploid lines having the genetic background of cultivar Shiokari (Kinoshita and Shinbashi 1982). The morphogenesis of the haploid plants was investigated in comparison with that of the diploid plants.

The percentage of callus formation in different dwarf lines showed a considerable variation. The highest, 27.6%, was obtained in an extreme dwarf line conditioned by d-18^h. Plants regnerated from the pollen calli included albinos, mixoploids, and other variants besides the haploid and diploid plants. Twelve kinds of haploid dwarf lines were established after vegetative propagation of regenerating plants.

The morphological features of dwarf lines with different genes were retained in haploids, and they could be distinguished from one another as at the diploid level. However, the variations in plant height and culm length among the haploid dwarf types were not comparable to those at diploid level (Fig. 1). There was a significant interaction between the effect of haploidy and that of a dwarfing gene. In addition, the haploid plants showed some increase against their diploid counterparts in panicle number and spikelet number reflecting rather luxuriant vegetative growth caused by their complete sterility. In the distribution pattern of internode lengths, the haploid and diploid lines did not differ much, except for certain variants induced by anther culture. The haploid and diploid lines showed significant correlations in most of characters examined. It may be concluded that dwarfing genes produce similar effects on morphogenesis at both haploid and diploid levels.

Three haploid variants, ID-7b, ID-11a and ID-11b, were induced by anther culture. Their internode patterns markedly differed from those of corresponding diploids suggesting that mutations occurred during anther culture.

Fig. 1. Idiogram of panicle and internodes in a series of isogenic dwarf lines both at haploid and diploid levels. Panicle (top), first, second, third and lower internodes are shown in each figure.

Kinoshita, T. and N. Shinbashi, 1982. Identification of dwarf genes and their character expression in the isogenic background. Genetical studies on rice plant, 83. Jpn. J. Breed. 32:219-231.