Strategy and utilization of a herbicide resistance gene in two-line hybrid rice

• Published in: Molecular breeding 2007-10, Vol.20 (3), p.287-292
• Main Authors: Xiao, Guoying, Yuan, Longping, Sun, Samuel S. M
• Format: Article
• Language: English
• Subjects: Bombardment; Crop production; Disease control; Disease resistance; Fertility; Grain; Herbicide resistance; Herbicide resistance gene; Herbicides; Hybrid systems; Low temperature; Molecular biology; Oryza; Oryza sativa; Particle bombardment; Plant biology; Purity; Purity of hybrid seed; Rice; Seeds; Spraying; Sterility; Sterility fluctuation; Transgenic rice; Two-line hybrid rice; Variation
• ISSN: 1380-3743; 1572-9788
• DOI: 10.1007/s11032-007-9091-0

Hybrid rice plays an important role in China's aim to improve rice production as it accounts for some 50% of rice planting area but produces about 60% of the total rice grain. However, the existing three-line system used in hybrid rice production has its limitations. The two-line system, which makes use of photoperiod-sensitive genic male-sterile (PGMS) and thermo-sensitive genic male-sterile (TGMS) lines to generate the male-sterile parental line, was developed to overcome some of these limitations. The sterility of the male-sterile line of two-line hybrid rice, however, fluctuates when the temperature-sensitive phase of fertility encounters abnormal low temperatures during hybrid seed production, which induces selfing and decreases the purity of hybrid. We describe here the strategy of utilizing a herbicide resistance gene in two-line hybrid rice to eliminate this fluctuation in the sterility of the P/TGMS lines during hybrid seed production and reports the development of the herbicide resistance restorer line Bar68-1 and its herbicide-resistant early season hybrid rice Xiang125s/Bar68-1. When the restorer line and its derived hybrid are herbicide resistant, the selfed seeds can be removed easily from the hybrid by herbicide spraying. A herbicide resistance gene bar was transferred into a restorer line by particle bombardment. The resulting transgenic restorer line Bar68-1 and its hybrid Xiang125 s/Bar68-1 inherited stable herbicide resistance. The purity of Xiang125s/Bar68-1 was increased by spraying the seed bed with herbicide, which resulted in a significant increase in yield, grain quality, and disease resistance in comparison to the controls in a regional trial.