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以及由病毒、细菌和真菌引起的许多疾病的威胁。在上个世纪，农业现代化包括开发可以用作杀虫剂来杀死害虫和病原体的化学品。杀虫剂可能非常有效，但也有缺点，即它们可能通过对非目标物种的影响而潜在地破坏环境，这些物种可能包括有益的动物，如授粉动物或掠食性昆虫。这一点，再加上零售商和消费者对某些传统农药可能对人体产生毒性的相关关切，导致寻找对环境和消费者都友好的虫害和疾病控制替代办法的压力越来越大。基于基因改造的控制方法是有效的，但在许多地区会遇到越来越多的消费者抵制。另一种方法是病虫害综合治理（IPM），它将种植方法与利用寄生虫或害虫捕食者作为生物防治手段相结合。然而，IPM很少提供使用传统农药可以实现的完全“清洁作物”，并且需要在IPM武器库中添加其他工具。一种可能有所贡献的方法是开发增强植物自然防御机制的方法。我们的建议围绕着一种最近在兰开斯特开创的方法。它是基于这样一项发现：将植物种子浸泡在通常参与植物防御反应的天然植物激素中，会导致从这些种子生长出来的植物的病虫害抗性长期增强。我们之前已经证明，使用一种特殊激素茉莉酸（JA）的种子处理对一系列作物物种都有效，包括番茄、甜椒、黄瓜、小麦和玉米，并增强了对不同类型害虫的抵抗力，包括蚜虫、毛虫和螨虫。虽然使用诸如JA之类的化学物质通过施用于生长中的植物来激活天然植物抗性的想法并不新鲜，但对种子进行处理可以提供持久的保护而不会对植物生长或种子结实产生不利影响的发现是新颖的，并且为农业和园艺的部署提供了一种简单的策略。然而，我们目前还不知道植物是如何“记住”激活剂在种子上的应用，从而在随后受到昆虫或病原体的攻击时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。我们将比较经过种子处理和未经种子处理的植物在虫害发生前后的分子（基因表达和表观遗传印记）和生化（挥发性有机化合物）变化，以便开始了解种子处理如何导致更高水平的虫害抗性。该项目的第二个重要方面将是测试另一种化合物-氨基丁酸（BABA）的有效性，该化合物在用作番茄种子处理时，已知可启动水杨酸依赖防御和细胞壁防御（与对致病真菌和卵菌的抗性有关）。通过了解如何将化合物用作种子处理来增强植物的抗性，并通过评估它们提供保护的病虫害范围，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.