Establishing Of Maize Genetic Transformation System Mediated By Agrobacterium Tumefaciens And Study Of Arabidopsis CBF1 Transgene Maize

Maize is one of the important crops.in national economy, but climate factors limit its distribution or yield in China. It is mainly planted in in poorly irrigated drought areas and chilling including regions of high latitude areas of second frigid zone and high altitude of tropical or subtropical zone, where drought and chilling damage occur frequently. So it is very important to develop varieties resistant to chilling and drought stresses. Studies on regulation of COR in Arabidopsis have resulted in the discovery of a family of transcriptional activators, CBF1, one member of the gene family, controls the expression of a battery of COR in Arabidopsis and other cold tolerant plant species, which improve plant tolerance to low temperature and drought stresses. In our experiment, we constructed expression vectors carrying CBF1 gene and bar marker gene, transformed the inbreds 50land Xianzaol 7 by bombardment and Agrobacterium tumefaciens. The aim of our research are to discover whether or not the CBF1 transcriptional activator in maize genome regulate tolerance genes to low temperature and drought and illustrate the possibility of breeding new maize varieties by Arabidopsis CBF1.As to bombardment method, the result are as following, the resistant calli rate are 45.65% of Xianzaol? and 29.12% of 501 resistance calli rate. Finally, 99 regenerated independent transfomants (196 seedlings), including 96 independent transformants (193 seedlings) of Xianzaol? and 3 independent transformants of 501,were transplanted to field. Only 54 independent transformants (73 seedlings) and 3 independent transformants of 501 were transplanted successfully. PCR analysis of five Xianzaol7and two 501 regeneration plants indicated that four Xianzaol7 and one 501 were positive, showing that CBF1 genes were integrated into maize genome.Factors influencing maize transformation mediated by Agrobacterium tumefaciens were r.tudied and were established an efficient transformation system. By this method, we got 27.01% of Xianzaol7 and 31.55% of 501 resistance calli. However, the regeneration plants from resistance calli were very few for long time calli culture (3-4months). Finally, only one independent transformant (2 seedlings) was obtainted.Although the maize genetic transformation mediated by Agrobacterium tumefaciens has not been perfect, we established a foundation for an efficient transformation system mediated by Agrobactrium tumefaciens. At the same time, the CBF1 gene generation plants of by bombardment will promote the research of Arabidopsis CBF1 transgene maize.