Construction Of Plant Expression Vector With Chitinase Gene For Monocotyledon Genetic Transformation And Establishment Of Regeneration Sstem Of Maize

Fungus diseases have long been a great threaten to the production and quality of maize crop. Great efforts have been done to deal with these diseases, but few cultivars are efficient enough to maintain their disease-resistant ability for a long time because of the quick variation of pathogens or the friability of disease resistance of the cultivars. Traditional breeding techniques are both time and labor consuming, which makes it hard for them to be employed nowadays when elite corn cultivars resistant to fungus are in great needs. What further limited the successful application of traditional breeding technique in maize breeding is that resistance genes are scarce in maize crop. So gene engineering technique as an efficient breeding method applying to maize breeding will definitely accelerate the course of maize breeding as well as enrich the resistance resources to fungi pathogens because this technique makes it possible to transfer genes between/among different species. Thus, by replacing fragement Res in plasmid pBIUA with the aimed fragement Chi which was cut off from plasmid pETChi ,the monocotyledonous high-effective plant expression vector pBIUA driven by ubi promoter of maize has been constructed. This work has been helpful to transfer chi gene to elite maize inbred lines in the present research in the hope of enhancing resistance in maize.The manipulation of plant genetic engineering is based on the establishment of regeneration system. Immature embryos of six elite maize inbred-lines , Zong3, 87-1, Zheng58, Chang7-2,137, K12, which were widely used in hybridization, were used to induce callus as explants. Then establishing regeneration systems of Zong3, Zheng58 and K12, which had the higher induced frequence of callus. Furthermore, several elements on plant regeneration were researched. The results showed that: 2,4-D had deep influence on the callus initiation, and the perfect 2,4-D concentration of the callus initiation was 2.0mg/l; the callus initiation of maize relied more on genotypes, and the rate of callus initiation was from 93.1%(Zong 3)to 24.4%(Chang 7-2);when the maize callus differetiated into plantlets, 6-BA was needed and what was the best concentrations depended on genotypes,and the most suitable 6-BA concentration for Zong3 was 1.5mg/l, while Zheng58 and K12, 1.0 mg/l; the transplant procedure (differentiation medium→regeneration medium→vermiculite) could increase survival...