| I. Research Notes Callus formation in wheat anthers1) Taro FUJII National Institute of Genetics, Misima, Japan Anthers containing pollen grains at tetrad stage in diploid, tetraploid and hexaploid wheats were used as the materials. They were planted on modified White's medium supplemented with 20 mg/l of 2, 4-D and solidified with 0.9% agar in a test tube. They were incubated under dark condition and constant temperature of 25C. The pH of medium was adjusted to 5.8. Callus formations started about 4 weeks after planting. Differences in the production of callus among the species were observed and the results are given in Table 1. Among diploid species, about 3% of explants formed callus in the wild T. aegilopoides, while the tendency to callus formation was very low in the cultivated T. monococcum. A similar tendency was also observed, in tetraploid species, namely, wild T. dicoccoides showed a relatively high callus production of about 18%, and no callus at all was found in about 600 explants of cultivated T. durum. It is interesting that no callus was observed in two cultivated hexaploid wheats, T. aestivum and T. spelta, so far examined. Callus tissues obtained from the above diploid and tetraploid species could be successfully subcultured with the same or other kinds of synthetic medium and have been maintained over several passages up to present. Although the ability to form callus is lower in diploid than in tetraploid species, its growth was better in the former. The use of haploid or polyhaploid callus cells for mutation experiments is under way. In spite of the very slow growth, modified White's medium supplemented with 2,4-D was the best for wheat anthers, among three types of medium, namely, Erickson's, and Murashige and Skoog's. Callus induction was also tried in roots of diploid wheats, maize and Arabidopsis which are our materials for mutation experiments. Calli were formed easily in these materials, and their growth was more vigorous than of those obtained from anthers. Roots were formed from Arabidopsis callus on modified White's medium while wheat and maize did not form roots on the same medium. Requirements for callus formation and differentiation must be different by different materials. (The guidance in culture techniques of Dr. Hiroo NIIZEKI is gratefully acknowledged.) (Received August 3, 1970) |
| 1) Presented at 5 minutes communication of the 2nd International Conference of Plant Tissue Culture held in Strasbourg, 9 July, 1970. |