The Herbicide-resistant Gene EPSPS As An Indicator In Heterosis Utilization And Its Rapid Transfer Among Materials Of Cotton

Cotton is an important economic crop. Weeds in cotton field is one of the troubles that farmer faced. Base on the excellent characteristics such as high yield and quality, it has become a hot aspect in transgenic plant breeding research to increase the resistant potential of cotton to glyphosate, as well as to utilize glyphosate resistance as an indicator in the heterosis utilization.In this study, nine combinations were made between nine lines with good agronomic traits and fiber quality and a glyphosate-resistant new line via no-emasculation-pollination method. The optimum concentration and the spraying time of glyphosate were determined, and heterosis of cotton yield and fiber quality traits was analyzed. Meanwhile, EPSPS gene was transformed to five elite cotton lines by using rapid backcross introgression for generation advancement under local conditions in order to obtain BC4 generation. The results are as follows.1. The optimum concentration of glyphosate was 2g/L and 2.25 g/L to discriminate resistant glyphosate and non-resistant parental varieties or hybrids, respectively. This concentration can kill non-glyphosate-resistant plants, while preserving the resistant glyphosate plants. And the most appropriate time of spraying was three-leaf stage.2. F1 generation of nine combinations grown in the field were sprayed with the optimum glyphosate solution and tested by PCR method. The results showed that the positive ratio of hybrid of different combinations ranged from 33.6% to 62.52%. Among them, the positive ratio of four crosses was more than 50%.3. Shikimic acid contents of F1 generation of different combinations were determined using HPLC method. The results showed that the trend of shikimic acid content of different combinations was in consistent with the trend of glyphosate resistance. To a certain extent, the resistance capacity of different crosses was slightly different due to their different genetic background.4. The heterosis analysis of F1 of different combinations showed that the range of lint yield is from 1777.1 to 2441.3 kg/hm2, which increased significantly. Glyphosate-resistant cotton yield increases were mainly due to the increase in boll number. The average increase ratio of the 9 combinations was 27%, and the highest combination achieved 49%. The fiber strength of competitive advantage could be as high as 15%.5. Five elite lines were utilized to cross and backcross with resistant glyphosate line via rapid backcross introgression for generation advancement under local conditions including immature embryo culture, grafting and plant growth regulation. In a year, four backcross generations of five crosses were obtained, which will lay a foundation for further breeding the new resistant glyphosate varieties.