Plant Molecular and Cellular Biology Program, Agronomy Department, Genetics Institute, University of Florida, IFAS, Gainesville, FL, USA.
Theor Appl Genet. 2010 Sep;121(5):919-29. doi: 10.1007/s00122-010-1360-3. Epub 2010 May 30.
Bahiagrass (Paspalum notatum Flüggé) is the predominant forage grass in the southeastern US. The commercially important bahiagrass cultivar 'Argentine' is preferred for genetic transformation over sexual diploid cytotypes, since it produces uniform seed progeny through apomixis. Pseudogamous apomictic seed production in Argentine bahiagrass may contribute to transgene confinement. It is characterized by embryo development which is independent of fertilization of the egg cell, but requires fertilization with compatible pollen to produce the endosperm. Pollen-mediated gene transfer from transgenic, glufosinate-resistant apomictic bahiagrass as pollen donor at close proximity (0.5-3.5 m) with non-transgenic sexual or apomictic bahiagrass cultivars as pollen receptors was evaluated under field conditions. Hybridization frequency was evaluated by glufosinate herbicide resistance in >23,300 seedlings derived from open-pollinated (OP) pollen receptor plants. Average gene transfer between transgenic apomictic, tetraploid and sexual diploid bahiagrass was 0.03%. Herbicide-resistant hybrids confirmed by immuno-chromatographic detection of the PAT protein displayed a single copy bar gene identical to the pollen parent. Hybrids resulting from diploid pollen receptors were confirmed as triploids or aneu-triploids with significantly reduced vigor and seed set as compared to the parents. Transmission of transgenes to sexual bahiagrass is severely restricted by the ploidy difference between tetraploid apomicts and diploid sexual bahiagrass. Average gene transfer between transgenic apomictic tetraploid and non-transgenic, apomictic tetraploid bahiagrass was 0.17%, confirming a very low frequency of amphimixis in apomictic bahiagrass cultivars. While not providing complete transgene containment, gene transfer between transgenic apomictic and non-transgenic bahiagrass occurs at a much lower frequency than reported for other cross-pollinating or facultative apomictic grasses.
雀稗（Paspalum notatum Flüggé）是美国东南部主要的饲料草。商业上重要的雀稗栽培品种“阿根廷”因其通过无融合生殖产生均匀的种子后代而优于有性二倍体细胞型，用于遗传转化。阿根廷雀稗的假性无融合生殖种子生产可能有助于转基因的限制。其特征在于胚胎发育独立于卵细胞的受精，但需要与相容的花粉受精才能产生胚乳。在田间条件下，评估了近距（0.5-3.5 m）处作为花粉供体的转基因抗草甘膦无融合生殖雀稗与非转基因有性或无融合生殖雀稗作为花粉受体之间的花粉介导的基因转移。通过来自开放授粉（OP）花粉受体植物的>23,300 株幼苗的草甘膦除草剂抗性评估杂交频率。平均转基因无融合生殖、四倍体和有性二倍体雀稗之间的基因转移为 0.03%。通过免疫层析检测 PAT 蛋白证实的抗除草剂杂种显示与花粉亲本相同的单拷贝 bar 基因。与亲本相比，来自二倍体花粉受体的杂种被确认为三倍体或非整倍体三倍体，活力和结实率显著降低。转基因向有性雀稗的传递受到四倍体无融合生殖与二倍体有性雀稗之间的倍性差异的严重限制。转基因无融合生殖四倍体与非转基因、无融合生殖四倍体雀稗之间的平均基因转移为 0.17%，证实无融合生殖雀稗品种中存在非常低的异交频率。虽然不能完全包含转基因，但与其他异花授粉或兼性无融合生殖草的报道相比，转基因无融合生殖与非转基因雀稗之间的基因转移频率要低得多。
