Creation Of Novel High Lint Percentage Cotton Germplasm With IaaM Gene

Cotton is an important economic crop and also the most important natural fiber crop. Cotton fiber is the most important textile fiber crop in the world, so it occupies an important position in the national economy and people’s life. With the development of economy, the demands of cotton fiber quality become higher and higher. But it is limited to simultaneously improve the yield and quality of cotton fiber by conventional breedingBased on cross breeding and back cross breeding techniques, the gene, iaaM was transferred to some cotton lines which have good comprehensive character. Fifteen hybridized and three backcross combinations with iaaM were obtained. The technologies, cotton immature embryo culture in vitro and cotton grafting, were improved based on previous study. The results were as follows.1. The gene of iaaM was confirmed to have obvious effect on the lint and micronaire of F1 hybrid. Lint percentage of 15 hybridized combinations ranged from 40.29% to 47.13%, averaged 43.71%. The range of micronaire of 15 hybridized combinations was 3.89 ~ 4.69, and the average of micronaire of 15 hybridized combinations was 4.35.2. Twelve F4 generations materials with high lint percentage and quality of cotton fiber were obtained through choosing F3 generation. The average of lint percentage and micronaire of 12 F4 generations materials were 50.08% and 4.29 respectively, the highest lint percentage was 54.97%.3. Cotton immature embryo culture in vitro was improved in the study. In this medium, 71.37% of immature embryo of 23 to 24 days post anthesis could germinate directly into healthy seedling on the suitable condition.4. Cotton grafting technology was also improved. Positive plantlets from cotton immature embryo culture in vitro with true leaves were used as scion. The seedlings during bud stage and anthesis were used as rootstock, with the survival rate of 100% and 93% respectively. Averagely, the first flower bloomed 55.2 days after grafting using rootstock during bud stage, and 58.1 day using rootstock during anthesis, reduced four days and one day respectively.5. Using the improved immature embryo in vitro culture and cotton grafting technology combining with PCR, the iaaM gene was transferred into three cotton lines such as Nongda 8, Pin 4 and Youxi 3. At present the plants of BC5 were obtained.