Heritable Priming by Trichoderma: A Boon to Plant Health and Food Security 

One of the biggest challenges for food security in the 21st century is to improve crop yield stability through the development of disease-resistant crops. Plants are constantly exposed to potentially pathogenic microbes present in their surrounding environment. Population burst, loss of agricultural land due to climate change, erosion and lack of water require that we reduce production losses such as those caused by pests and pathogens as much as possible. As a result, biotic stress, a loss of fitness caused to an individual by other organisms places a major constraint on plant growth. In the absence of genetic resistance in crops, food production heavily depends on the use of chemicals to control pathogens. Despite their effectiveness, chemicals-based plant defence has detrimental environmental consequences and creates risks to the wider environment. Modern synthetic chemicals usually have reduced environmental toxicity; however, they are expensive and only available to advanced agricultural production systems. Moreover, as with antibiotics, the discovery of new chemicals to control plant disease is difficult and extensive use of current agents may result in the selection of pathogen strains tolerant to pesticides.  Reducing the dependence of food production on chemical control is a key goal of plant pathology research. One of the major goals of plant research in the 21st century is to increase our understanding of the plant defence system and unravel how this is manipulated by pathogens, in order to engineer crops with both durable resistance against pathogens and increased yields.  Plants have evolved a sophisticated immune system to resist pests and diseases. Apart from their innate immune system controlling pre-programmed defence reactions, plants can also increase the responsiveness of their immune system in response to selected environmental signals. This phenomenon is known as “defence priming”. Priming is one of the most economical and effective modes of resistance because it prevents wasteful metabolic consumption in plants. The fitness costs of priming are lower than those of constitutively activated defences, suggesting that priming functions as an ecological adaptation of the plant to respond faster to a hostile environment. Although defence priming rarely provides full protection, its broad-spectrum effectiveness, long‐lasting durability and inherited to future generations make it attractive for integrated disease management. Plant defence priming and Intergenerational Immune Priming (IGIP) will be discussed in relation to wheat crop improvement and sustainability.