Cold-conserved hybrid immature embryos for efficient wheat transformation

Transgenesis through biolistic of immature embryos is the most convenient way to introduce artificially new genes in bread wheat (Triticum aestivum L.). However, only a few genotypes can be efficiently transformed. To improve the transformation of wheat varieties, we stored immature seeds at room temperature or 4 °C during 4 or 7 days and extracted immature embryos prior to transformation. Shelling stops the embryo’s growth and almost all the embryos formed a callus on selective media when stored at 4 °C for 4 or 7 days (respectively 87% and 99%). We also used hybrid immature embryos derived from a cross between a transformable line (Courtot) and a non-transformable line (Chinese Spring) for biolistic transformation. Hybrid embryos showed the same response to biolistic than the responsive parent. All together, these results improve significantly the biolistic protocol for wheat transformation by reducing the number of mother plants in the greenhouse, and improve the transformation of additional genotypes through hybrid transformation.