Production and analysis of transgenic maize with improved salt tolerance by the introduction of AtNHX1 gene

The AtNHX1 gene and hygromycin phosphotransferase (hpt) gene were introduced into the embryonic callus cells of maize (Zea mays L.) elite inbred lines DH4866, Qi 319 and Luyuan 16106 by Agrobacterium-mediated method. Plantlets were obtained from the hygromycin-resistant calli after screening. PCR analysis and Southern blot hybridization indicated that there were 22.8% transgenic plants among the regenerated plants. The transformation frequencies were obviously affected by Agrobacterium concentration, the genotype of callus and co-cultivation duration. The segregations of AtNHX1 gene in the progeny were not easily to be elucidated, and some lines showed Mendelian segregations. The screening of salt tolerance indicated that the salt tolerance of some transgenic plants and their progenies were improved significantly and the seeds of some lines were able to germinate and grow in the presence of 0.8%-1.0% sodium chloride. Northern blotting analysis of T-2 transgenic plants indicated that the salt tolerance of plants was correlative with the transcription level of AtNHX1 in the leaves.