一种不育系解决机械化制种和不育系混杂的设想与实践

劳动力成本的不断提高,劳动者减轻劳动强度的愿望日趋强烈,迫切要求杂交水稻制种过程的机械化.在制种过程中水稻光温敏核不育系遇到低温、某些细胞质雄性不育系遇到异常高温均会产生自交结实,导致杂种F1代中不育系混杂,从而降低杂交种的纯度、影响大田产量.培育对一种除草剂具有抗性、同时对另外一种除草剂敏感的水稻不育系,即抗/感除草剂水稻不育系,可以一次性解决杂交水稻机械化制种和不育系混杂两个问题.苯达松是一种对水稻安全的除草剂,但苯达松敏感隐性突变体对苯达松敏感.草铵膦、草甘膦、咪唑乙烟酸等能杀死水稻,但对具有抗性基因的水稻安全.利用苯达松敏感核不育系185BS、926BS与抗草铵膦的水稻杂交,选育出了抗草铵膦/感苯达松的水稻光温敏核不育系09F316BS、09F317BS、09F319BS和09F320BS.利用苯达松敏感核不育系185BS为受体进行遗传转化,获得了抗草铵膦和草甘膦/感苯达松的水稻光温敏核不育系EB185BS.由于这些不育系具有抗除草剂的特点,而恢复系不具备,制种时不育系与恢复系可以混播,待授粉完成后喷施除草剂杀死恢复系,成熟后机械化收割不育系上所结杂交种子,而不需要提前人工割刈恢复系；而且恢复系在不育系中均匀分布也可以提高异交率.如果在制种过程中遇到异常低气温,造成不育系少量自交结实而混杂在杂种F1代中,可以通过在杂种F1代秧田喷施苯达松杀死混杂的苯达松敏感不育系,杂交种由于野生基因的显性作用而不受伤害,从而可以保证大田F1代的纯度；此外,秧苗期喷施除草剂可以代替田间种植鉴定杂交种纯度,减少了种植鉴定中的土地占用和人工费用.本设想也可以运用到其它作物,通过培育一种抗/感除草剂的不育系来一次性解决机械化制种和清除不育系混杂的问题.

Strategy and Practice on Solving Mechanization of Seed Production and Mixture of Male Sterile Line Using One Type of Sterile Line

The continuously increase of labor cost and constantly increasing desire to reduce labour intensity urgently demand for mechanization of hybrid seed production.In process of hybrid seed production,the self-fertility seeds will produce when the photoperiod-sensitive and/or theromo-sensitive genic male sterile(PTGMS) line meets abnormal low temperature and some cytoplasm male sterile(CMS) line encounters irregular high temperature,which results in the decrease of the F1 seed purity and grain yield by mixture of the PTGMS or CMS line in hybrid seeds.The herbicide-resistant and herbicide-sensitive male sterile line is not only resistant to one kind of herbicide but also sensitive to another kind of herbicide,can solve the two problems,i.e.mechanical harvest of hybrid seeds and mixture of male sterile line.The herbicide bentazone is safe for rice plant except the sensitive mutants with recessive gene.The herbicide glufosinate,glyphosate,imazethapyr,etc can kill rice plant except the plant with resistant gene.The glufosinate-resistant and bentazon-sensitive PTGMS line 09F316BS,09F317BS,09F319BS and 09F320BS were developed from the cross of bentazone sensitive PTGMS line 185BS or 926BS and glufosinate resistant rice plant.The PTGMS line EB185BS was resistant to both glufosinate and glyphosate,and was sensitive to bentazon,was generated from transformation of 185BS,a bentazon sensitive PTGMS line.Due to these PTGMS lines were herbicide resistance and the restorer lines were not,they could be sowed or transplanted mixedly in the field of hybrid seed production;the restorer line could be killed by spraying herbicide after ponination and the matured F1 seeds on the plant of PTGMS line could be harvested mechanically without the need for mowing the restorer line by hands in advance.Moreover,the uniform distribution of the restorer line in the PTGMS line could increase the outcrossing rate.If encountering the abnormal low temperature during hybrid seed production,the selfed seeds of the PTGMS line would produce and contaminate the F1 hybrid seed.The contaminated PTGMS line could be removed in the seedling bed by spraying herbicide bentazon,while the seedling of hybrid rice could survive due to the dominance of wild-type gene,which ensured the purity of hybrid rice in the field.In addition,spraying herbicide in the seedling bed could replace planting in field to judge the purity of hybrid seed,which reduced the occupation of land and labor cost in purity identification by planting in the field.This strategy can also apply in other crops to solve the mechanical harvest of hybrid seed and mixture of male sterile line by developing the herbicide-resistant and herbicide-sensitive male sterile line.