SPT技术的新进展
由美国先锋公司研制的杂交种子生产技术（seed production technology，SPT）采用转基因方法成功地解决了细胞核雄性不育的保持问题。该技术将育性恢复基因R、花粉致死基因F和种子筛选标记基因S三个表达盒连锁构建到一个载体上并导入保持系中。由于R-F-S型雄配子含有F基因而不能存活，该保持系只能产生一种可育的雄配子类型r，所以用rr作母本与该保持系杂交可以直接生产不育系，且不含转基因成分。该技术巧妙地将转基因技术和传统的杂交育种方法相结合，使杂种优势资源利用率大大提高，且生产的杂交种属于非转基因而不需要经过漫长的安全性评价试验。目前已在玉米雄性不育制种中得到应用。
如今，杜邦先锋公司的研究人员利用核算内切酶Ems26+造成了水稻、小麦、高粱的Ms26基因的突变，成功创造了细胞核雄性不育系，使得SPT技术未来可以应用到更广泛的单子叶作物上。
Plant Biotechnol J. 2016 Oct 14.
Targeted mutagenesis of a conserved anther-expressed P450 gene confers male sterility inmonocots
Author
A. Mark Cigan, Manjit Singh, GeoffreyBenn, Lanie Feigenbutz, Manish Kumar, Myeong-Je Cho, Sergei Svitashev, JoshuaYoung
Trait Technologies, DuPont Pioneer, USA
Summary
Targeted mutagenesis using programmable DNA endonucleases has broad applications for studying gene function in planta and developing approaches to improve crop yields. Recently, a genetic method that eliminates the need to emasculate the female inbred during hybrid seed production, referred to as Seed Production Technology, has been described. The foundation of this genetic system relied on classical methods to identify genes critical to anther and pollen development. One of these genes is a P450 gene which is expressed in the tapetum of anthers. Homozygous recessive mutants in this gene render maize and rice plants male sterile. While this P450 in maize corresponds to the male fertility gene Ms26, male fertility mutants have not been isolated in other monocots such as sorghum and wheat. In this report, a custom designed homing endonuclease, Ems26+, was used to generate in planta mutations in the rice, sorghum and wheat orthologs of maize Ms26. Similar to maize, homozygous mutations in this P450 gene in rice and sorghum prevent pollen formation resulting in male sterile plants and fertility was restored insorghum using a transformed copy of maize Ms26. In contrast, allohexaploid wheat plants that carry similar homozygous nuclear mutationsin only one, but not all three, of their single genomes were male fertile. Targeted mutagenesis and subsequent characterization of male fertility genes in sorghum and wheat is an important step for capturing heterosis and improving crop yields through hybrid seed.
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