| Maize (Zea mays L.) is a very important crop used as food and feedstuff. And it also can be used as raw material in modern food, medicine and chemical industry fields. Meanwhile it is a very good model plant in plant genetic transformation. After Rhodes and other scientists got an integrated transgenic plant of maize in 1988, we have made progress in the establishment of maize receptors system, researches on transformation techniques and improvement of important trait characters that become more and more important in crops breeding.The starch of maize is widely used in many fields. The starch of maize includes amylose and amylopectin, and their content ratios are 28% and 72% respectively. And amylose of maize has more value, as it is widely used in many fields such as food, food science, medicine, textile, paper-making, wrappers, oil industry, environment protection, optic fiber, altitudinal printing plugboard, electronic chips and so on. Amylose has a potential use that is to produce photodegradable films, which is one of the best and effective ways to solve "plastic pollution" problems. Therefore, it is of vital importance to breed and select good high amylose varieties of maize, which can bring us great social and economic value. But there are only a few of researches on breeding high amylose varieties of maize nowadays in China. So we should pay more attention to it. In this experiment, we established two kinds of receptors systems that are maize inbred lines with high amylose and general maize inbred lines. We could solve those kinds of problems by using gene-engineering method that is to transfer genes that control the formation of starch into maize inbred lines. Then we transferred anti-sense expression vector of starch branch enzyme gene of maize into maize inbred lines by using Agrobacterium Tumefaciens-mediated transformation and Pollen Tube Pathway Method, which can effectively control the formation of amylopetin to increase the content of amylose so that we can get the lines with high amylose content.In this experiment, we used the immature callis of high amylose content of maize inbred lines such as C9, C15, C21, C31, C41 and general maize inbred lines such as Zong 31, Mo 17 and P12 that had been pollinated for 10 to 14 days as receptor materials. We used different kinds of mediums to initiate immature embryo and optimized the culture conditions. And we also did researches on some important factors that have effects on the initiation of callis by using immature embryos as explants. The results indicated that we could initiate callis from different types of maize inbred lines. But the initiation rates mainly depended on genotypes, types of medium, and the concentration of phytohormones, etc.. For the initiation of maize callis of different genotypes, we could initiate embryo callis by using Ms, N6, MB mediums. But the transformation rates were distinctly different. We could initiate good embryo callis with a higher initiation rates than other ones by using MB and N6 mediums. For different genotypes of maize inbred lines, the initiation rate was higher by using 2,4-D with the concentration 2mg/L. Meanwhile, the experiment also indicated that when we used sucrose and glucose as the sources of C for different mediums, there were differences among differentgenotypes of maize inbred lines. We could get higher initiation rate by using 20g/L sucrose as source of C for maize inbred lines with high amylose content. And we used 20-25g/L sucrose as source of C for subculture. We could get higher initiation rate and better embryo callis while we used 30g/L sucrose or 20g/L sucrose and 10g/L glucose as source of C. And it was also good and suitable for us to subculture the callis. Above all, we established the receptors systems of genetic transformation for both high amylose content of maize inbred lines and general maize inbred lines and found out the effective methods to initiate, subculture, differentiate and root. And it also provides us base to transform maize embryo callis to establish regeneration r... |
PDF Full Text Request