TISSUE-CULTURE RESPONSE OF CIMMYT ELITE BREAD WHEAT CULTIVARS AND EVALUATION OF REGENERATED PLANTS

Six elite CIMMYT bread wheat genotypes Pavon 76, Seri M82, Opata M85, Mochis T88, Baviacora M93, and the advanced line Attila were evaluated for their response to in vitro tissue culture. Donor plants were grow n at El Batan and CIANO experiment stations in Mexico in 1992. Immatur e embryos, about 1.0 mm in length, were excised and placed scutellum s ide up on callus initiation media. Basal N6 medium supplemented with d icamba (E1), MS medium containing 2,4D (E3), or MS medium containing 2 ,4D plus different amino acids (E5) was used for callus initiation and maintenance. Plant regeneration and rooting were achieved on basal MS medium with IAA and BAP. Embryogenic calli with regeneration potentia ls of 10-92% were obtained on E3 and E5 media; each embryo produced 5- 50 plants. A total of 800 regenerated plants were transferred to pots in the greenhouse for evaluation and seed production. Of the regenerat ed plants, 85% were morphologically normal. reached full maturity, and produced seeds. Seeds (R1) of 360 plants regenerated from Mochis T88, Baviacora M93, and Attila were planted in the field. Field observatio ns indicated that embryos cultured on E3 medium resulted in 29% of the progeny producing deviating plants, compared with 21% of those grown on E5 medium. These results will form the basis for future efforts aim ed at transforming CIMMYT bread wheat varieties.