Cell wall lignin programme: Manipulating lignin to improve biofuel conversion of plant biomass

世界对能源和燃料的需求继续增加，但目前的石油和天然气资源有限。这一点，以及对二氧化碳水平上升和气候变化的日益关注，重新引起了人们对替代燃料来源的兴趣。植物生物质可用于生产能源，可以直接燃烧，也可以作为细菌和酵母生产生物燃料的原料。然而，将植物材料转化为生物燃料（如生物乙醇）的过程还不是非常有效，需要改进以使其在经济上可行。改进用于生物燃料生产的植物材料的一种方法是操纵植物细胞壁的结构，因为这些壁中的抗性聚合物防止微生物酶将植物材料降解为单糖和乙醇。在这方面，最重要的细胞壁聚合物之一是木质素。幸运的是，我们知道很多关于木质素是如何制造的，以及如何在木本植物中操纵它。然而，许多可用于生产能源的植物生物质来自草，因此需要更多的研究来使我们能够在这些类型的植物中操纵木质素。大麦是一个很好的模型，可以种植用于能源应用的草，而且大麦的研究工具比大多数其他草都多。大麦和小麦秸秆废料也可以成为生物燃料生产的有用资源，大麦中的大多数遗传发现通常很容易转移到小麦中。该项目旨在确定木质素含量和结构如何影响（1）从大麦秸秆中释放的糖的量;（2）这些糖转化为生物燃料的效率;以及（3）通过燃烧可以从大麦秸秆中释放的能量。这将表明如何最好地操纵聚合物，使其更容易从植物生物质生产生物燃料。我们还旨在确定是否有任何木质素生物合成基因对大麦抗病性或茎强度很重要，以便我们可以确定如何在保持植物健康的同时操纵木质素。我们分离的基因和遗传标记可直接用于能源作物改良育种计划。因为我们将研究许多不同的大麦品种，我们也将能够确定目前哪些品种最适合生物燃料生产和燃烧热量和能量。

World demand for energy and fuel continues to increase but current resources of oil and gas are finite. This, and increasing concern about rising CO2 levels and climate change, has generated renewed interest in alternative fuel sources. Plant biomass can be used to produce energy, either directly by burning it or by using it as the raw material from which bacteria and yeasts can produce biofuels. However the process of converting plant materials into biofuel (such as bioethanol) is not yet very efficient and needs to be improved to make it economically viable. One way of improving plant materials for biofuel production would be to manipulate the structure of plant cell walls, since it is resistant polymers in these walls that prevent microbial enzymes from degrading the plant material into simple sugars and ethanol. One of the most important cell wall polymers in this respect is lignin. Fortunately, we know quite a lot about how lignin is made and how it can be manipulated in woody plants. However much of the plant biomass that could be used to produce energy comes from grasses, and more research is therefore needed to enable us to manipulate lignin in these types of plant. Barley is a good model for the grasses that might be grown for energy applications, and there are more research tools available for barley than for most other grasses. Barley and wheat straw waste could also be useful resources for biofuel production, and most genetic discoveries in barley are usually easily transferable to wheat. This project aims to determine how lignin content and structure influence (1) the amount of sugars that can be released from barley straw; (2) how efficiently these sugars can be converted into biofuels; and (3) the amount of energy that can be released from barley straw by combustion. This will indicate how the polymer can best be manipulated to make it easier to produce biofuels from plant biomass. We also aim to determine whether any lignin biosynthesis genes are important for barley disease resistance or stem strength, so that we can determine how to manipulate lignin while keeping plants healthy. The genes and genetic markers that we isolate can be used directly in energy crop improvement breeding programmes. Because we will be looking at a lot of different barley varieties, we will also be able to identify which current varieties are best for biofuel production and for burning for heat and energy.