ABSTRACT. Genetic manipulation using linear DNA was applied to the common wheat variety Xindong No. 26 via particle bombardment with the aim to improve bread-making quality of flour. Initially, 2 biolistic parameters, helium pressure and target distance, were optimized using plasmid pAHC25. We transformed wheat immature embryo scutella with the linear 1Dx5 gene without selectable markers. The highest transient β-glucuronidase expression was obtained when scuttles were bombarded at 1100 psi with a 9-cm target distance. Using the optimized parameters, the transformation of the common wheat variety Xindong No. 26 was carried out using the linear 1Dx5. Three transgenic plants were identified from 1003 transgenic plants, yielding a transformation frequency of 0.4%. A sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis confirmed that the 1Dx5 gene was expressed in 4 T1 seeds of the transgenic plants. These experiments indicate the possibility of obtaining marker-free transgenic wheat plants via particle bombardment using the minimal gene cassettes with the particle bombardment parameters.

To improve bread making quality of flour and produce transgenic plants free of selectable markers, Immature embryo scutella from Xindong No. 26 were used as explants for establishing an efficient and stable wheat regeneration system, then he linear expressing box of 1Dx5 without selectable markers was transformed into the immature embryo of Xin Dong No. 26 via particle bombardment. The result showed that MS medium containing 2, 4-D 1.5 mg/L and Dicamba 0.5 mg/L for callus induction, R medium containing ZT 1 mg/L and 2,4-D 0.01 mg/L for callus differentiation were the best efficiency, the differentiation frequency of callus was 90%; Transformed plants were screened by PCR, three transgenic plants were detected among 1000 transformed plants, only yielding the transformation rate of 0.3%. The compositions of HWM-GS were analyzed by SDS-PAGE. The HMW-GS gene 1Dx5 was expressed in some seeds of transgenic plants. Our studies lay the foundations for obtaining marker-free transformants using the linear gene via particle bombardment.