Cell biology of plant natural products

将使用气相色谱仪(GC)分析植物天然产物的复杂混合物的化学成分。与大多数其他化学分离方法相比，该仪器具有更高的分辨率、更高的灵敏度和精密度。将溶液中复杂的化学混合物加热到足够高的温度，使整个溶液汽化。然后，蒸汽在高压下被迫通过多孔基质。不同的化学成分将以不同的速度通过基质，具体取决于它们的物理大小和性质，允许精确分离数百种不同的化学物质，有时仅相差一个原子。这种GC将用于研究两个系统的天然产品：植物角质层分泌和青蒿素生物合成和运输。植物角质层由分泌的脂类组成，它们保护植物免受昆虫、紫外线和非气孔失水的伤害。尽管角质层在农业和植物生态中很重要，但对植物表皮细胞如何合成和分泌这一保护层的了解还很初级。我们正在研究这些脂类是如何从表皮细胞输出到表面的，其中的机制完全未知。青蒿素被用作一种有效的抗疟疾疗法的一部分，这种疗法被称为基于青蒿素的联合疗法(ACT)。青蒿素被证明非常有效，但不断上升的生产成本使发展中国家的许多人很难获得这种药物，那里最需要青蒿素。目前，这种药物唯一经济的来源是从植物青蒿素的分泌腺中获得。只有一小部分青蒿腺中的精油含有青蒿素。了解这些化合物是如何合成和分泌到腺体中的，对于提高青蒿素的医疗生产至关重要。

A gas chromatograph (GC) will be used to analyze the chemical composition of complex mixtures of plant natural products. This instrument offers superior resolution and greater sensitivity and precision than most other chemical separation methods.  A complex mixture of chemicals in solution is heated to sufficiently high temperature to vaporize the entire solution.  This vapour is then forced through a porous matrix at high pressure.  The different chemical components will pass through the matrix at different rates, depending on their physical size and properties, allowing for precise separation of literally hundreds of different chemicals, sometimes differing only by a single atom.  This GC will be used for studying natural products in two systems:  plant cuticle secretion and artemisinin biosynthesis and transport.   The plant cuticle consists of secreted lipids, which protect the plant from insects, uv light, and non-stomatal water loss.  Understanding of how plant epidermal cells synthesize and secrete this protective layer is rudimentary, despite the importance of the cuticle in agriculture and plant ecology.  We are studying how these lipids exported from the epidermal cells to the surface,   the mechanism of which is completely unknown. Artemisinin is used as part of an effective anti-malarial treatment known as artemisinin-based combination therapy (ACT).  Artemisinin been shown to be very effective, but the rising cost of production is making this drug difficult to obtain for many in the developing world, where it is needed the most.  Currently, the only economical source of this drug is from the secretory glands of the plant, Artemisia annua.  Only a fraction of the essential oils in the glands of Artemisia contains artemisinin.  Understanding how these compounds are synthesized and secreted into the glands will be essential to improving artemisinin production for medical use.