Abstract:

The maintainer lines of wild abortive（WA）cytoplasmic male sterile line mainly come from early indica rice cultivars with the genetic background of Nan-Te-Hao and Ai-Zizhan and so on in the valley of Changjiang River due to the genetic restriction of the relationship between the WA cytoplasm and its restorer line. The high content of amylose and big chalkiness for these cultivars has long restricted the improvement of hybrid rice quality. The study was aimed at improving rice quality high efficiently and rapidly by using a new breeding approach. A male sterile cytoplasm of O. rufipogon, named FA cytoplasm, was obtained through nuclear substitution of the Wild Rice（O. rufipogon）with the nuclear of cultivated rice by backcrosses. The results showed that the male sterile line with FA cytoplasm was different from WA and HL sterile lines (table 5) in the relationship between restorer line and maintainer line. The restorer and maintainer line of WA and HL both could be used as the maintainer line of FA cytoplasmic sterile line, but not as its restorer line. It was a newly found resource of rice male sterile cytoplasm. FA cytoplasm was free from the genetic confinement of the relationship between the restorer line and maintainer line of WA and HL, enlarging the circle of maintainer liners so that good cultivated cultivars could be developed into fine male sterile lines. Jinnong 1A, a newly developed male sterile line with FA cytoplasm, had a high degree of stable sterility with superior agronomic traits and good resistance to diseases. It flowered earlier with good rice quality. All the twelve indexes of rice qualities reached the first or second class standards issued by the Agricultural Department of China, which substantially improved the rice quality and comprehensive traits and established a solid foundation for the development of fine quality hybrid rice. The development of FA cytoplasm and the male sterile line of Jinnong 1A made it possible to open up a new way of breeding high standard of fine quality male sterile lines. It was of great significance to the enriching of genetic diversities of hybrid rice cytoplasm and the increasing of hybrid rice quality and yield by leaps and bounds.

Key words: Rice, cms, cms-FA, Good quality male sterile line