VARIATION IN TRANSFORMATION FREQUENCIES AMONG 6 COMMON WHEAT CULTIVARS THROUGH PARTICLE BOMBARDMENT OF SCUTELLAR TISSUES

The transformation technique in common wheat has already been establis hed by using microprojectile bombardment and scutellar tissues of imma ture embryos. In this study, in vitro culture response of immature emb ryos and the production of transgenic wheat plants were examined in si x common wheat cultivars, i.e., Chinese Spring, Akadaruma, Haruhikari, Shiroganekomugi, Norin 12, and Norin 61. In all genotypes, more than seven hundred immature embryos were bombarded with a plasmid containin g a bialaphos-resistant gene under control of the rice actin 1 gene (A ct1) promoter. Although the transient expression of the reporter gene encoding beta-glucuronidase following the rice Act1 promoter was simil ar in five of the six cultivars tested, the frequency of stable transf ormation varied with the genotype. The frequency of transformation was the highest in Akadaruma and Norin 12 of the six wheat cultivars; ind ependently transformed plants were produced from 1.4% and 1.7% of bomb arded embryos, respectively. On the other hand, the immature embryos o f Norin 61 and Shiroganekomugi showing low efficiency of in vitro cult ure generated no transgenic plants. This variation of the transformati on frequency was generally caused by the difference in the in vitro cu lture response with the genotype, rather than the efficiency of the in troduction of the transgene into wheat cells by particle bombardment.