Agrobacterium-Mediated Genetic Transformation of Bread Wheat (Triticum aestivum L.) Using Immature Embryos

Abstract

Wheat is considered the most important food crop globally. Genetic transformation provides a method for genetic manipulation of wheat to enhance its agronomic performance. Wheat is a difficult crop for genetic transformation. Agrobacterium-mediated transformation facilitates precise integration of genes into the plant genome compared to biolistic approach. In the present research, we studied the effect of acetosyringone concentrations, genotypes and embryo explant types (intact or longitudinally halved-embryos or fragmented latitudinal pieces) on transformation frequency for immature embryos derived from four different genotypes of bread wheat (Achtar, Amal, Mehdia, and Rajae). Embryo explant types were inoculated with A. tumefaciens strain EHA101 harboring the plasmid vector pTF101.1 carrying the barley HVA1 drought tolerance gene and bar-selection marker for resistance to the herbicide phosphinothricin. The effects of the genotype, embryo explant type, and acetosyringone concentrations on the frequency of phosphinothricin resistant bread wheat plantlets regeneration after transformation with Agrobacterium were significant. Transgenic plants were generated from longitudinally-halved immature embryo and intact-immature embryos, whereas, no transgenic plantlets were obtained from fragmented immature embryos. Based on the PCR analysis, the transformation efficiency of T0 plants for the two genotypes varied from 0.66% (‘Rajae’ from the longitudinally halved-immature embryo cultured with no acetosyringone) to 0.33% (‘Achtar’ genotype from intact-immature cultured with 200 μM of acetosyringone).