Variation in transformation frequencies among six common wheat cultivars through particle bombardment of scutellar tissues.

Abstract

The transformation technique in common wheat has already been established by using microprojectile bombardment and scutellar tissues of immature embryos. In this study, in vitro culture response of immature embryos and the production of transgenic wheat plants were examined in six 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 containing a bialaphos-resistant gene under control of the rice actin 1 gene. (Act1) promoter. Although the transient expression of the reporter gene encoding beta-glucuronidase following the rice Act1 promoter was similar in five of the six cultivars tested, the frequency of stable transformation varied with the genotype. The frequency of transformation was the highest in Akadaruma and Norin 12 of the six wheat cultivars; independently transformed plants were produced from 1.4% and 1.7% of bombarded embryos, respectively. On the other hand, the immature embryos of Norin 61 and Shiroganekomugi showing low efficiency of in vitro culture generated no transgenic plants. This variation of the transformation frequency was generally caused by the difference in the in vitro culture response with the genotype, rather than the efficiency of the introduction of the transgene into wheat cells by particle bombardment.