Custers J B, Oldenhof M T, Schrauwen J A, Cordewener J H, Wullems G J, van Lookeren Campagne M M
Department of Development Biology, Centre for Plant Breeding and Reproduction Research (CPRO-DLO), Wageningen, Netherlands.
Plant Mol Biol. 1997 Dec;35(6):689-99. doi: 10.1023/a:1005846527674.
In order to modify the early stages of pollen development in a transgenic context microspore-specific promoters are required. We tested two putatively microspore-specific promoters, the Bp4 promoter from rapeseed and the NTM19 promoter from tobacco. Expression of the gus and barnase reporter genes under the control of these two promoters was studied in transgenic tobacco. Contrary to expectations, the Bp4 promoter became active only after the first pollen mitosis, and not in the microspores. The NTM19 promoter turned out to be highly microspore-specific and directed very high levels of gus expression to the unicellular microspores. The NTM19-barnase transgene caused cell-autonomous death at the mid-unicellular microspore stage, whereas Bp4-barnase induced cell ablation of early to mid-bicellular pollen. Both promoter-barnase transgenes did not affect the sporophyte and were inherited through the female germline. These results show that both the NTM19 and Bp4 promoters are expressed only in the male germline, and that the NTM19 promoter is an excellent tool to direct high levels of transgene expression exclusively to the microspores. This may have important biotechnological applications.
为了在转基因环境中调控花粉发育的早期阶段，需要小孢子特异性启动子。我们测试了两个推测的小孢子特异性启动子，来自油菜的Bp4启动子和来自烟草的NTM19启动子。在转基因烟草中研究了这两个启动子控制下的gus和barnase报告基因的表达。与预期相反，Bp4启动子仅在第一次花粉有丝分裂后才活跃，而在小孢子中不活跃。结果表明，NTM19启动子具有高度的小孢子特异性，并将非常高水平的gus表达导向单细胞小孢子。NTM19-barnase转基因在单细胞小孢子中期引起细胞自主死亡，而Bp4-barnase诱导早期至中期二细胞花粉的细胞消融。两个启动子-barnase转基因均不影响孢子体，并通过雌性生殖系遗传。这些结果表明，NTM19和Bp4启动子都仅在雄性生殖系中表达，并且NTM19启动子是将高水平转基因表达专门导向小孢子的优良工具。这可能具有重要的生物技术应用。
