在杂交作物分子育种中利用普通核雄性不育的几个可能途径

由一对隐性基因控制的普通核雄性不育性遗传方式能够满足对植物最佳雄性不育系选育的要求，是水稻等作物杂种优势利用的极好遗传工具。如果能解决其不育系繁殖问题，将优于现有的其他杂种优势利用方式。克隆出普通核雄性不育性的可育基因，通过叶绿体转化，将核雄性不育性可育基因向普通核雄性不育株细胞质转移，创造普通核雄性不育株的保持系；通过种子成熟后表达的启动子；和以位点特异性重组技术为基础的基因开关以及化学诱导启动子的利用，都可能繁殖出100％不育株率的普通核雄性不育系，创造普通核雄性不育性利用的新途径，对植物杂种优势利用产业有十分重要的意义。

Potential Ways to Use Spontaneous Genic Male Sterility in the Molecular Breeding of Hybrid Crops

Spontaneous genic male sterility will be a best genetic tool for hybrid seed production if uniform male sterile (ms, hereafter) lines are available. Some strategies were suggested to obtain such lines by means of cloning and transformation of male fertility (MF, hereafter) genes of spontaneous genic male sterility: (1) transferring MF gene into plastid genome of ms plants to suppress ms gene. The male fertile transgenic plants can be used as the maintainers to reproduce the genic male sterile lines when crossed to ms plants. (2) To comprise a lethal gene such as ribosomal inhibitor protein gene to transiently activate promoters that are active only in late embryogensis, then splice it with the MF gene, and transfer them into ms plants. The spikelets of transgenic plants may be fertile at heading stage and killed by the lethal gene when matured. When the transgenic plants are crossed with ms plants, their hybrid seeds with MF gene will be killed. The others with same nuclear as ms plants will survive. Immature seeds with the lethal gene can be harvested before maturing as the maintainer. (3) Gene switch system such as Cre/lox can snip out a stretch of DNA in plant genome. Its repressor protein prevents Cre recombinase gene from being switched on. Such stimulant as the antibiotic tetracycline can block the repressor protein. We can splice a DNA sequence that can be recognized by Cre recombinase to each end of a MF gene. By transferring this stretch of DNA and the gene switch system into ms plants, we can obtain a transgenic plant having homozygous MF gene, ms gene and the gene switch system. The transgenic plant may reproduce seeds like a conventional variety. When it is treated with the stimulant, the repressor protein will be blocked. The recombinase gene can work and snip out the MF gene. The fertile transgenic plants become male sterile then and can be used as the female parent for hybrid seeds production. (4)Take the native promoter from MF gene and replace it with a promoter that only functions in response to a chemical (such as antibiotic tetracycline), transfer the recombinant into ms line. The transgenic line would be fertile when the inducing chemical is present and used for the multiplication of ms plants. For hybrid seeds production the chemical will not be applied. Artificial male sterile genes and their restoration genes are also suggested to be used in the strategies.