Abstract：
Hybrid seed production technology (SPT) using genic recessive male sterility is of great importance in maize breeding. Here, we report a novel SPT based on a maize unilateral cross-incompatibility gene ZmGa1F with an extremely low transgene transmission rate (TTR). Proper pollen-specific ZmGa1F expression severely inhibits pollen tube growth leading to no fertilization. The maintainer line harbors a transgene cassette in an ipe1 male sterile background containing IPE1 to restore ipe1 male fertility, ZmGa1F to prevent transgenic pollen escape, the red fluorescence protein encoding gene DsRed2 for the separation of male sterile and fertile seeds, and the herbicide-resistant gene Bar for transgenic plant selection. When the maintainer line is selfed, gametes of ipe1/transgene and ipe1/- genotypes are produced, and pollen of the ipe1/transgene genotype is not able to fertilize female gametes due to pollen tube growth inhibition by ZmGa1F. Subsequently, seeds of ipe1/ipe1 and ipe1/transgene genotypes are produced at a 1:1 ratio and could be separated easily by fluorescence-based seed sorting. Not a single seed emitting fluorescence is detected in more than 200,000 seeds examined demonstrating that the pollen-tube-inhibition (PTI)-based TTR is lower than what has been reported for similar technologies to date. This PTI-based SPT shows promising potential for future maize hybrid seed production.
摘要：
利用基因隐性雄性不育的杂交制种技术（SPT）在玉米育种中具有重要意义。这里,我们报告了一种基于玉米单侧交叉不兼容基因ZmGa1F的新型SPT，其转基因传播率（TTR）极低。正确的花粉特异性ZmGa1F表达严重抑制花粉管生长，导致不受精。保持系在含有IPE1的ipe1雄性不育背景中带有一个转基因盒，以恢复ipe1雄性生育力，ZmGa1F防止转基因花粉逃逸，红色荧光蛋白编码基因DsRed2用于分离雄性不育和可育种子,和抗除草剂基因Bar用于转基因植物选择。当保持者线自交时，产生ipe1/转基因和ipe1/-基因型的配子，由于ZmGa1F抑制花粉管生长，ipe1/转基因基因型的花粉无法使雌配子受精。随后，ipe1/ipe1和ipe1/转基因基因型的种子以1：1的比例产生，可以通过基于荧光的种子分选轻松分离。在所检查的超过200,000个种子中未检测到发射荧光的单个种子,这表明基于花粉管抑制(PTI)的TTR低于迄今为止针对类似技术所报道的。这种基于PTI的SPT显示出未来玉米杂交种子生产的有希望的潜力。
