| Plant regeneration from stem-derived calluses of wheat
Takiko SHIMADA Laboratory of Genetics, Faculty of Agricutture, Kyoto University, Kyoto, Japan Regenerated plants from the wheat cultures would be useful for genetic studies and for improving the quality of wheat. With wheat (Triticum aestivum), however, plants have been obtained from wheat cultures derived from various organs only sporadically (SHIMADA et al. 1969, DUDITS et al. 1975, O'hara and Street 1978). Recently, I obtained cultures capable of regeneration from the young embryos of wheat. This paper describes cultures capable of regeneration derived from stem tissues of various species of wheat. Many restored plants have been obtained from long-term subcultured calluses of T. dicoccoides. Materials and methods Plant materials were : Triticum aestivum cv. Chinese Spring, T. dicoccoides spontaneonigrum, T. carthlicum stramineum, T. durum (Gulab), Aegilops squarrosa strangulata, Ae. squarrosa typica No. 2 and synthesized wheats ; ABD-1 (T. dicoccoides spontaleeonigrum x Ae. squarrosa typica No. 2). ABD-4 (T. carthlicum stramineum x Ae. squarrosa typica No. 2), ABD-12 (T. dicoccoides spontaneonigrum x Ae. squarrosa strangulata), ABD-14 (T. durum (Gulab) x Ae. squarrosa strangulata) and ABD-16 (T. durum (Gulab) x Ae. squarrosa meyeri). These strains were kindly provided by Dr. M. Tanaka, Plant Germ-plasm Institute, Kyoto University, and Dr. J. TABUSHI, Kyoto Bunkyo College. The stem pieces (2 mm long) were taken 5 cm below the ear neck from the uppermost internode of the culum, and were placed aceptically on an agar slant media in test tubes, each containing 10 ml of RM-64 medium (LINSMAIER and SKOOG 1965) supplemented with 2,4-D at 2.0 mg/l. They were incubated at 25-28C under continuous illuminaton. Results and Discussion Stems of Dinkel, Emmer, synthesized wheats and Aegilops were cultured on RM-64 medium containing 2.0 mg/l of 2,4-D. The results after one month of incubation are shown in Table 1 . Calluses were induced from stems of all species tested. In some species, shoots redifferentiated from the callusses after one month of incubation. The frequencies of calluses with shoots were 5.0, 12.0, 5.0 and 16.0% in T. dicoccoides, ABD-1, ABD-4 and ABD-12, respectively. Shoot redifferentiation did not occur in the calluses of T. aestivum, T. durum, T. carthlicum and Ae. squarrosa, and the calluses of ABD-14 and ABD-16 whose parents are T. durum and Ae. squarrosa did not show shoot redifferentiation. These results suggest that the differences in the efficiencies of regeneration among the species depend on the genotypes. Stem calluses of T. dicoccoides, showing localized chlorophyll development, were subcultured every 30 to 40 days on RM-64 medium containing 2.0 mg/l of 2,4-D. When these calluses subcultured for 1.5 years were transferred to 2,4-D-free RM-64 medium, they formed many leaves and roots. And when the differentiated plantlets grew about 10 cm long, they were planted in soil. Most of them grew normally in the greenhouse. Some differentiated plantlets had white stripes on their leaves. The chromosome numbers in the root tip cells of regenerated plantelets were normal diploid (2n=28). These calluses derived from the stem are similar to those from the embryo of T. aestivum with respect to the capability of regeneration (SHIMADA and YAMADA 1979). Literature Cited DUDITS, D., G. NEMET and Z. HAYDU 1975. Study of callus growth and organ formation in wheat (Triticum aestivum) tissue cultures. Canad. J. Bot. 53: 957-963. LINSMAIER, E.M. and F. SKOOG 1965. Organic growth factor requirements of tobacco tissue cultures. Physiol. Plant. 18: 100-127. O'hAHARA, J.F. and H.E. STREET 1978. Wheat callus culture : The initiation, growth and organogenesis of callus derived from various explant sources. Ann. Bot. 42: 1029-1038. SHIMADA, T. 1978. Plant regeneration from callus induced from wheat embryo. Japan. J. Genetics 53: 371-374. SHIMADA, T. , T., T. SASAKUMA and K. TSUNEWAKI 1969. In vitro culture of wheat tissues. I. Callus formation, organ redifferentiation and single cell culture. Canad. J. Genet. Cytol. 11: 294-304. SHIMADA, T. and Y. YAMADA 1979. Wheat plants regenerated from embryo cell cultures. Japan. J. Genet. 54: 379-385. |