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 β-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.

An efficient wheat transformation procedure: transformed calli with long-term morphogenic potential for plant regeneration

“…Using this calculation, an overall transformation efficiency of 28% was obtained with our protocol. Regardless, the minimum transformation efficiency (6.3%) reported here is higher than those previously reported (0.1-2.5%) (Weeks et al 1993;Nehra et al 1994;Altpeter et al 1996;Barro et al 1997;Cheng et al 1997;Dobrzanska et al 1997;Takumi and Shimada 1997). The higher transformation rates reported here are likely due to the induction of long-term morphogenic callus and the early application of high selection pressure.…”

“…Recently, a number of advances have been made in the development and optimization of procedures for transformation of several monocot crops including wheat (Altpeter et al 1996;Blechl and Anderson 1996;Barro et al 1997;Cheng et al 1997;Dobrzanska et al 1997;Takumi and Shimada 1997). For practical use in breeding programs, a large number of independently transformed lines are desirable so that those with stable transgene integration and a high level of expression can be selected (Altpeter et al 1996).…”

“…These manipulations generally produce many regenerants but few true transformants. The transformation efficiencies are usually 0.1-2.5% (Weeks et al 1993;Nehra et al 1994;Altpeter et al 1996;Barro et al 1997;Dobrzanska et al 1997;Takumi and Shimada 1997). Using these methods, several hundred to thousands of immature embryos or explants are typically bombarded to obtain about ten transgenic T0 plants.…”

Genetic transformation technology in the Triticeae

“…For example, candidate genes anticipated to confer tolerance to abiotic stress or resistance to a pathogen can best be analysed in the context of a susceptible plant genetic background. In surveys of both wheat and barley germplasm, several elite lines have proven amenable to transformation, albeit often at the cost of transformation efficiency (Takumi and Shimada 1997, Wu et al 2003, Hensel et al 2008. In particular, the German winter wheat cultivar "Certo" appears relatively easy to transform both via biolistic (Varshney and Altpeter 2001) or via gene transfer by means of Agrobacterium .…”

Genetic Transformation of Durum Wheat (Triticum durum Desf.) through Particle Bombardment of Scutellar Tissues.

“…reichenbachii and T. aethiopicum, because their regeneration frequencies from cultured immature embryos were low. The efficient production of transgenic wheat plants requires the induction of green-spotted calli from more than 90% of immature embryos [23]. For the production of transgenic plants in these varieties, the in vitro culture system should be improved to increase the regeneration frequency markedly.…”