Generation Of Transgenic Maize (Zea May L.) Plants Overexpressing AtGPX3 And AtCHX23

Maize is one of the main grain crops in our country. Maize productivity is often adversely affected by drought and salt stresses, which can significantly decrease the yield of Zea may plants. Therefore, it is essential to improve drought and salt tolerance of maize plants for food security of our country.With the development of genetic engineering techniques, people can use the transgenic technology to effectively improve stress tolerance of maize and obtain drought and salt resistant new maize varieties.The Agrobacterium-mediated transgenic method in maize has many advantages over other gene transformation methods, for example clear transformation mechanisms, a high frequency of single or low copy insertion events et al. However, the transformation efficiency using Agrobacterium in maize is relatively low. The efficiency is markedly influenced by many factors including maize genotype, explant type, explant growth state, medium composition, hormone composition and ratio, type of Agrobacterium strains, concentration and pH of infection solution, and the culture conditions after infection and so on. Hence, establishing an effective transgenic transformation system with stable heredity, high infection rate, easy and efficient maize regeneration method is a key step for obtaining transgenic maize plants.We constructed two transformation vectors harbouring drought tolerance gene AtGPX3 and salt tolerance gene AtCHX23 and transformed these vectors into callus cells of immature embryos from hybrid Hi-â…¡, or inbred lines Zheng 58 and Qi 319 maize plants using Agrobacterium mediated transgenic method.These calli were then subcultured, selected, differentiated, and regenerated. A large number of transgenic seedlingswere obtained. Furthermore, we identified some positive transgenic plants by smearing PPT on tender leaf tip or by using PCR method. Seeds of transgenic Hi-â…¡plants have been obtained. At the same time, good calli of maize inbred lines Zheng 58 and Qi 319 were generated, and gene AtGPX3 and AtCHX23 were transferred into the callus cells. Transgenic plants from the cells were gained. Additionally, the Agrobacterium-mediated transformation protocols were reinvestigated. We found that the type D based medium with L-glutamine can help to improve the embryogenic callus inducing rate. It is known that the inhibition of Agrobacterium propagation after Agrobacterium mediated transformation of maize calli is critical transgenic plant regeneration from callus cells.In this study, we optimized the methods of inhibiting reproduction of Agrobacterium by decreasing the concentration of the infection solution (OD600 = 0.3-0.4), shortening the infection time (about 5 min), washing the calli more times with sterile water and immersing the calli in Cef-contained water for a longer time (about 60 min), without reducing the transformation efficiency. The knowledge lays a solid foundation for the investigation of maize engineering in the future.