过表达NtAGPase小亚基基因提高烟叶淀粉含量和生物量

Overexpression of NtAGPase small subunit gene increases leaf starch content and tobacco biomass

摘要:

发展以非粮食作物为原料制备乙醇等生物燃料既可缓解全球能源危机，又能减低粮食作物用于生物燃料对粮食安全的威胁。烟草Nicotiana tabacum是一种生物量较高的经济作物，培育富含淀粉的新型烟草，可专用于燃料乙醇生产。文中克隆了烟草控制淀粉生物合成的ADP-葡萄糖焦磷酸化酶 (ADP-glucose pyrophosphorylase，NtAGPase) 小亚基基因NtSSU，并构建了NtSSU基因植物表达载体。通过农杆菌介导叶盘转化法在烟草中超表达NtSSU基因。转基因烟草植株表型鉴定显示，过表达NtSSU基因促进烟叶淀粉富集，烟叶淀粉含量从野生型17.5%升高到41.7%。转基因烟草的生长速率和生物量也显著增加。研究结果揭示，过表达NtSSU基因能有效调动光合产物碳通量更多地进入淀粉合成途径，提高生物质产量，且未对其他农艺性状产生负效应。因此，NtSSU基因可作为优异靶标基因应用于植物代谢工程以促进营养器官中淀粉的合成积累，从而开发专用于生产燃料乙醇的新种质。

Abstract:

Production of biofuels such as ethanol from non-grain crops may contribute to alleviating the global energy crisis and reducing the potential threat to food security. Tobacco (Nicotiana tabacum) is a commercial crop with high biomass yield. Breeding of starch-rich tobacco plants may provide alternative raw materials for the production of fuel ethanol. We cloned the small subunit gene NtSSU of ADP-glucose pyrophosphorylase (NtAGPase), which controls starch biosynthesis in tobacco, and constructed a plant expression vector pCAMBIA1303-NtSSU. The NtSSU gene was overexpressed in tobacco upon Agrobacterium-mediated leaf disc transformation. Phenotypic analysis showed that overexpression of NtSSU gene promoted the accumulation of starch in tobacco leaves, and the content of starch in tobacco leaves increased from 17.5% to 41.7%. The growth rate and biomass yield of the transgenic tobacco with NtSSU gene were also significantly increased. The results revealed that overexpression of NtSSU gene could effectively redirect more photosynthesis carbon flux into starch biosynthesis pathway, which led to an increased biomass yield but did not generate negative effects on other agronomic traits. Therefore, NtSSU gene can be used as an excellent target gene in plant breeding to enrich starch accumulation in vegetative organs to develop new germplasm dedicated to fuel ethanol production.