DNA Transfer from Wild Millet to Common Wheat by Asymmetric Somatic Hybridization

Following differing periods of long-term subculture and selection, two types of calli of the same wheat ( Triticum aestivum L. cv. Jinan 177) were obtained. The one (named Cha 9) grew fast and easily formed cell suspensions that were non-regenerable, but the protoplasts possessed a high division capacity. The other (named 176) was regenerable, but the derived protoplasts grew slowly. Fusion combination between either Cha 9 or 176 protoplasts and UV-treated wild millet (SetaHa italica L. Beaur.) protoplasts failed to produce regenerated green plants. However, when the two types of wheat protoplasts were mixed together as recipient and fused with wild millet, green plants were obtained. The hybrid nature of regener-ated calli and plants was confirmed by the analysis of cytological, isozyme, 5S rDNA spacer sequences and random amplified polymorphic DNA (RAPD). The chloroplast genomes of hybrids were analyzed with several wheat-specific chloroplast microsatellite (simple sequence repeat, SSR) primers. A hybrid clone carrying recipient DNA of Cha 9 and 176, as well as both nuclear and chloroplast donor DNA had a high regeneration capacity and produced more vigorous green plants than did the other clones.