Researches In Generating Early Flowering Germplasm Resources In Petunia And Tobacco Via Genetic Engineering

Flowering is one of the most important progresses for most plants during the transition from vegetative growth to reproductive growth.At present,mechanism of flower development has become one of the hot research topics in plant molecular biology. Petunia and tobacco,both as model plants in molecular manipulation,while petunia is also a widely used landscape plant,are playing much important roles in scientists' studies and people's life.The research of their flowering transition and obtaining mutants by transformation has great significance in the researches of the flower development mechanism and plant breeding.To deepening the acknowledge of the effect on heterologous expressed in plants of the FT homologes gene,the NT and PaFT were introduced into the genomes of flowering plant,wild-type petunia,tobacco and its various mutant strains of genetically modified materials through using the laef disc methods mediated by Agrobacterium tumefaciens, and the function of these two genes was more systemically analyzed.Meanwhile,we may create much more early flowering tobacco and petunia germplasm resources.The major results are as follows:1.Significantly early flowering NT transgenic plants were obtained using the leaf disc method mediated by Agrobacterium tumefaciens in Petunia hybbrida and Nicotiana tobacum.According to the phenotype,transgenic plants had dwarf plant type,and with significantly reduced number of leaves during their flowering conversion.The number of branches increased and all of them can produce inflorescence and normal seeds.In addition,transgenic plants had thinner and harder stem,and the anatomic analysis indicated that they had higher degree of lignification than that in the wild type plants.2.Basic on the early flowering NT transgenic tobacco,the twice transformation using hygromycin(HYG) as selection markers were performed and the characteristics during shoot differentiation and rooting were investigated.Selection pressures were determined as:30 mg/L HYG for shoot regeneration of leaves and also for rooting. 300 mg/L cefotaxime(Cef) had no great influences in organogenesis of adventitious shoot or root.3.Conditions suitable for twice transformation of NT transgenic tobacco,which carried nptⅡselection marker gene,were studied in detail.The transient and stable GUS expression indicated that gus gene,which were linked to hpt selection marker gene, had really been introduced into the genomes of NT transgenic tobacco.In our present study,the results show that it took a long time and relatively low rate in the second gene transformation than that in the first.4.Early flowering with white-flower and.double-flower tobacco mutants were obtained by twice transformation of white-flower tobacco and double-flower tobacco.PCR and phenotype analysis both indicated that PaFT gene had really been introduced into those plants of species mentioned above.In addition,the double-flower tobacco partly recovered to the wild type tobacco but still with early flowering phenotype after twice transformation.