Priming of plant defences against pests and pathogens using seed treatments.

农作物不断受到各种昆虫和其他动物害虫的威胁，以及由病毒、细菌和真菌引起的许多疾病。在上个世纪，农业现代化包括开发可用作杀虫剂的化学物质来杀死害虫和病原体。杀虫剂可能非常有效，但它们的缺点是，它们可能会通过对非目标物种的影响来破坏环境，这些非目标物种可能包括授粉或捕食性昆虫等有益动物。这一点，加上相关零售商和消费者对一些传统杀虫剂可能对人体产生毒性的担忧，导致了寻找既环保又有利于消费者的虫害和疾病控制替代方法的压力越来越大。基于基因改造的控制方法可以有效，但在许多领域遇到了消费者日益增长的抵抗力。另一种方法是病虫害综合管理(IPM)，它将种植实践与使用寄生虫或害虫捕食者作为生物防治手段相结合。然而，IPM很少提供使用传统杀虫剂可以实现的完全“清洁作物”，因此IPM武器库需要额外的工具。可能做出贡献的一种方法是开发方法来增强植物的自然防御机制。我们的建议围绕着最近在兰开斯特首创的一种这样的方法。它的发现是，将植物的种子浸泡在通常参与植物防御反应的天然植物激素中，会导致从这些种子长出的植物对病虫害的抵抗力长期增强。我们之前已经证明，使用一种特殊的激素茉莉酸(JA)处理种子对一系列作物物种都有效，包括番茄、甜椒、黄瓜、小麦和玉米，并提高了对不同类型的害虫的抗性，包括蚜虫、毛虫和螨虫。尽管使用JA等化学物质通过应用于生长中的植物来激活植物的天然抵抗力的想法并不新鲜，但对种子的处理可以提供长期保护而不会对植物生长或结实产生不利影响的发现是新的，并为在农业和园艺中部署提供了一种简单的策略。然而，我们目前还不知道植物如何“记住”激活剂在种子上的应用，当随后受到昆虫或病原体的攻击时，这会导致增强的诱导防御反应。因此，目前的项目将调查种子处理现象的基础科学。我们将比较种子处理前后植物分子(基因表达和表观遗传印记)和生化(挥发性有机化合物)的变化，以开始了解种子处理如何导致更高水平的抗虫害。该项目的第二个重要方面将是测试另一种化合物--β-氨基丁酸(BABA)的有效性，这种化合物在用作番茄种子处理时，既能激发水杨酸依赖的防御系统，又能激发基于细胞壁的防御系统(与病原真菌和卵菌的抗性有关)。通过了解化合物如何用作种子处理以提高植物的抗性，并通过评估它们提供保护的病虫害的范围，我们的项目将产生一个基本的知识库，可用于农业和园艺中的种子处理的开发。

Crop plants are constantly under threat from a variety of insects and other animal pests, as well as numerous diseases caused by viruses, bacteria and fungi. During the last century, agricultural modernisation included the development of chemicals that can be used as pesticides to kill pests and pathogens. Pesticides can be very effective, but have the disadvantages that they can potentially damage the environment via effects on non-target species, which might include beneficial animals such as pollinating or predatory insects. This, along with associated retailer and consumer concerns related to the possible human toxicity of some conventional pesticides, has led to increased pressure to find alternative approaches to pest and disease control that are both environmentally- and consumer-friendly. Control methods based on genetic modification can be effective, but meet increasing consumer resistance in many areas. Another approach is integrated pest management (IPM), which combines cultivation practices with the use of parasites or predators of pests as a means of biological control. However, IPM rarely delivers the completely 'clean crop' that can be achieved using conventional pesticides, and there is a need for additional tools in the IPM armoury. One approach that may contribute is the development of methods to enhance plants' natural defence mechanisms. Our proposal centres around one such method which has recently been pioneered at Lancaster. It is based on the discovery that soaking seeds of plants in natural plant hormones that are normally involved in plant defence responses, leads to a long-lasting increase in pest and disease resistance in plants grown from those seed. We have previously shown that seed treatments using one particular hormone, jasmonic acid (JA), are effective in a range of crop species, including tomato, sweet pepper, cucumber, wheat and maize and provide increased resistance to different types of pest, including aphids, caterpillars and mites. Although the idea of using chemicals such as JA to activate natural plant resistance by application to growing plants is not new, the discovery that the treatment of a seed can provide long-lasting protection without adverse effects on plant growth or seed set is novel, and provides a simple strategy for deployment in agriculture and horticulture. However, we currently do not know how a plant 'remembers' the application of the activator to the seed that leads to an augmented induced defence response when subsequently attacked by insects or pathogens. Thus, the current project will investigate the underpinning science of the seed treatment phenomenon. We will compare the molecular (gene expression and epigenetic imprint) and biochemical (volatile organic compound) changes in seed-treated and untreated plants before and after pest attack in order to begin to understand how the seed treatment leads to greater levels of pest resistance. A second important aspect of the project will be to test the effectiveness of another compound, beta-aminobutyric acid (BABA) that is known to prime both salicylic acid-dependent defences and cell wall-based defences (associated with resistance to pathogenic fungi and oomycetes), when used as a seed treatment in tomato. By understanding how compounds can be used as seed treatments to boost plant resistance and by assessing the range of pests and diseases against which they offer protection, our project will generate an essential knowledge base that can be used in the exploitation of seed treatments in agriculture and horticulture.