There is increasing pressure from a range of sources to minimise the use of chemical pesticides in agriculture and horticulture, and to find alternative approaches to pest and disease control that are both environmentally- and consumer-friendly. This project centres around one such method which has recently been pioneered at Lancaster. It is based on the discovery that soaking seeds 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. Although the idea of using plant hormones 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 or how that leads to an augmented induced defence response when the plant is 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. We will also examine the interactions between different activators of plant defence when used as seed treatments. 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.