Variations in callus formation from seeds in japonica indica their hybrids and large grain varieties in rice
Abe, T.; Sasahara, T.
Japanese Journal of Breeding 32(1): 53-60
On culture media differing in the concentration of mineral microelements (B, Mn, Zn, I, Mo, Cu and Co), Japonica cultivars except Somewake and Daikoku 1 generally exhibited high abilities of callus formation. Indica and large grain varieties (assumed to be Javanica type) and Japonica-Indica hydrids, however, showed relatively poor and varying abilities of callus formation, especially on the medium with reduced mineral microelements. There may be different requirements for the concentration of mineral microelements in callus formation among ecospecies and hybrids. Comparison between 'Murasaki'-'Daikoku' and 'Daikoku 1' having the same d-1 gene, indicated that the d-1 gene would not directly affect callus formation, and some background genes the suppressors may relate with the depression of callus formation. Semidwarf genes in 'Dee-geo-woo-gen' and 'Taichung native 1' apparently would not suppress calus formation. Slight depressions in many Japonica-Indica hybrids and IR-8 therefore were attributed to some background genes, i.e., the suppressors of callus formation other than the semi-dwarf genes. Such suppressors apparently occurred most frequently in Indica and large grain varieties. Variations on morphological appearance of callus in Japonica, Indica, their hybrids and large grain varieties were observed. The calluses of Japonica and large grain varieities tended to be friable, those of Japonica-Indica hybrids compact and those of Indica intermediate. Diversities from the expected callus formation, i.e., normal plant growth, white hairs, root cluster, white region and root-like structures, were likely to occur most frequently in the hybrids. Necrosis and/or brownish color of callus tissues were likely to occur in cultivars which showed reduced ability of callus formation.