Biotechnology Foundation Laboratories, Thomas Jefferson University, Philadelphia, PA, USA.
Plant Biotechnol J. 2010 Apr;8(3):277-87. doi: 10.1111/j.1467-7652.2009.00458.x. Epub 2009 Dec 23.
When grown for energy production instead for smoking, tobacco can generate a large amount of inexpensive biomass more efficiently than almost any other agricultural crop. Tobacco possesses potent oil biosynthesis machinery and can accumulate up to 40% of seed weight in oil. In this work, we explored two metabolic engineering approaches to enhance the oil content in tobacco green tissues for potential biofuel production. First, an Arabidopsis thaliana gene diacylglycerol acyltransferase (DGAT) coding for a key enzyme in triacylglycerol (TAG) biosynthesis, was expressed in tobacco under the control of a strong ribulose-biphosphate carboxylase small subunit promoter. This modification led to up to a 20-fold increase in TAG accumulation in tobacco leaves and translated into an overall of about a twofold increase in extracted fatty acids (FA) up to 5.8% of dry biomass in Nicotiana tabacum cv Wisconsin, and up to 6% in high-sugar tobacco variety NC-55. Modified tobacco plants also contained elevated amounts of phospholipids. This increase in lipids was accompanied by a shift in the FA composition favourable for their utilization as biodiesel. Second, we expressed in tobacco Arabidopsis gene LEAFY COTYLEDON 2 (LEC2), a master regulator of seed maturation and seed oil storage under the control of an inducible Alc promoter. Stimulation of LEC2 expression in mature tobacco plants by acetaldehyde led to the accumulation of up to 6.8% per dry weight of total extracted FA. The obtained data reveal the potential of metabolically modified plant biomass for the production of biofuel.
当烟草被用于能源生产而非吸烟时，它可以比几乎任何其他农作物更有效地产生大量廉价的生物质。烟草具有强大的油脂生物合成机制，其油脂含量可高达种子重量的 40%。在这项工作中，我们探索了两种代谢工程方法来提高烟草绿色组织中的油脂含量，以用于潜在的生物燃料生产。首先，我们在烟草中表达了拟南芥二酰基甘油酰基转移酶（DGAT）基因，该基因编码三酰基甘油（TAG）生物合成中的关键酶，受强核酮糖-1,5-二磷酸羧化酶小亚基启动子的控制。这种修饰使烟草叶片中的 TAG 积累增加了 20 倍，转化为提取脂肪酸（FA）的总量增加了约两倍，达到了烟草品种 Wisconsin 的干重的 5.8%，高糖烟草品种 NC-55 的干重的 6%。修饰后的烟草植物还含有更高水平的磷脂。脂质的增加伴随着 FA 组成的变化，有利于将其用作生物柴油。其次，我们在烟草中表达了拟南芥 LEAFY COTYLEDON 2（LEC2）基因，该基因是种子成熟和种子油脂储存的主调控因子，受诱导型 Alc 启动子的控制。在成熟的烟草植物中，通过乙醛刺激 LEC2 的表达，导致总提取 FA 的干重积累高达 6.8%。所得数据显示了代谢修饰的植物生物质用于生产生物燃料的潜力。
