Understanding the regulation of alkaloid biosynthesis in opium poppy and breeding new varieties

植物已经进化出大量复杂的化学结构，以抵御食草动物和病原体的攻击，并保护自己免受恶劣环境的侵害。这些化学结构也为植物提供了人类文明几千年来所依赖的药用特性。罂粟是世界上最重要的药用植物之一，是制药业使用的天然产品的最大单一来源。罂粟会产生鸦片类生物碱，如吗啡和可待因，它们是主要的止痛药之一。这些鸦片类生物碱的化学结构非常复杂，植物仍然是生产它们的最佳工厂。罂粟还能产生数百种其他生物碱，这些生物碱是其他几种药物的来源。罂粟的商业化种植采用大面积的耕作方法，作物用机械收割，然后运到工厂提取高价值的化学物质。葛兰素史克（GlaxoSmithKline）和强生（Johnson & Johnson）等制药公司都有自己的生产系统，从罂粟中生产鸦片类生物碱。我们在约克大学新农业产品中心的团队一直在与葛兰素史克公司合作开发新的罂粟品种，这些品种可以产生更多的吗啡类生物碱，如吗啡和可待因。我们也一直在研究罂粟是如何产生诺斯卡平的，这是一种抗肿瘤的生物碱，可以阻止人类细胞分裂。几十年来，诺斯卡平一直被用作人类止咳药。它在治疗各种癌症方面的有效性最近得到了证实，美国正在进行早期临床试验。我们特别想知道罂粟是如何制造诺斯卡平的，因为这将有助于我们培育出更多的新品种，并深入了解可能具有有用药物活性的相关分子。我们的工作导致了一项重大突破，最近发表在领先的杂志《科学》上（Winzer et al, Science 2012, 336:1704-8）。通过比较产生诺斯卡平和不产生诺斯卡平的罂粟品种，我们发现合成诺斯卡平的途径是由一个由十个基因组成的复杂集群控制的，这些基因编码着五种不同的酶类。这是迄今为止在植物中发现的最复杂的基因集群，为基因复制和重组驱动集群进化的过程提供了宝贵的见解。这一建议建立在我们激动人心的突破之上，旨在确定该基因簇是否也存在于其他能产生诺斯卡平的相关物种中。这将为基因簇进化的机制和过程提供新的见解。阐明我们发现的诺斯卡平生物合成生化途径的细节，将使我们能够更好地设计改善诺斯卡平及其相关分子生产的策略。诺斯卡平是由生物碱生物合成途径的另一个分支产生的，与生产吗啡和可待因的途径不同。调控分子流入这些不同分支的机制尚不清楚，我们现在第一次有了解决这个重要问题的工具和知识。回答这些问题不仅增加了我们对制药业天然产品原料方面最重要的药用植物的了解，还为我们提供了开发罂粟新品种的知识平台和工具，这些新品种可用于生产诺斯卡平、吗啡和可待因等生物碱。该提案的最终目标是使用分子育种方法开发具有优化水平的关键阿片生物碱的罂粟新品种，以造福制药工业和英国工业生物技术部门。

Plants have evolved to produce a vast array of complex chemical structures to fight off attacks from herbivores and pathogens and to protect themselves from often hostile environments. These chemical structures also provide plants with medicinal properties that human civilisation has relied on for millennia. Opium poppy is one of the most important medicinal plants in the world and represents the largest single source of natural products used by the pharmaceutical industry. Opium poppies produce opiate alkaloids such as morphine and codeine, which are one of the main classes of painkiller drugs. The chemical structures of these opiate alkaloids are very complex and plants remain the best factory for their production. Opium poppy also produces hundreds of other alkaloids and these have been a source of several other drugs. Opium poppy is commercially grown using broad acre farming methods and the crop is harvested mechanically and shipped to factories for extraction of the high value chemicals. Pharmaceutical companies such as GlaxoSmithKline and Johnson & Johnson have their own production systems for production of opiate alkaloids from opium poppy. Our group in the Centre for Novel Agricultural Products at the University of York have been working with GlaxoSmithKline to develop new varieties of poppy that produce more of the morphinan alkaloids such as morphine and codeine. We have also been investigating how opium poppy produces noscapine, an anti-tumour alkaloid that stops human cells dividing. Noscapine has been used as a human cough suppressant for decades. Its effectiveness in tackling various forms of cancer has been demonstrated more recently, and early stage clinical trials are in progress in the USA. We particularly wanted to discover how noscapine is made in opium poppy as this would help us to breed new varieties that make more of it and also to gain insight into related molecules that may also have useful pharmaceutical activity. Our work led to a major breakthrough that was published recently in the leading journal Science (Winzer et al, Science 2012, 336:1704-8). By comparing opium poppy varieties which make noscapine with those that do not we discovered that the pathway for synthesis of noscapine is controlled by a complex cluster of ten genes encoding five different enzyme classes. This is the most complex gene cluster ever found in plants and provides invaluable insights into the process of gene duplication and re-organisation driving cluster evolution.This proposal builds on our exciting breakthrough and aims to establish if the gene cluster is also present in other related species that also make noscapine. This will provide new insight into the mechanisms and processes involved in gene cluster evolution. Elucidating details of the biochemical pathway we discovered for noscapine biosynthesis will make us better able to design strategies for improved production of noscapine and related molecules. Noscapine is produced by a separate branch of the alkaloid biosynthesis pathway to the one used to produce morphine and codeine. What regulates the flow of molecules into these different branches is not understood and we now have the tools and knowledge to address this important question for the first time. Answering these questions not only adds to our knowledge of the most important medicinal plant in terms of natural product feedstock for the pharmaceutical industry, it also provides us with the knowledge platform and tools to develop new varieties of opium poppy that are optimised for production of alkaloids such as noscapine, morphine and codeine. The final objective of this proposal is to use molecular breeding methods to develop new varieties of opium poppy with optimised levels of key opiate alkaloids for the benefit of the pharmaceutical industry and the UK industrial biotechnology sector.