Increasing ascorbic acid and iron levels in tomatoes to enhance human nutrition and plant abiotic stress tolerance

The predicted increase of global warming poses a large risk for crop productivity even in protected cropping systems. Tomatoes have a narrow range of optimal growing temperatures and even when grown in fully controlled glasshouse environments, heat stress can trigger flower abscission and limit fruit yield as well as affect fruit development and maturity. Fluctuations of yields caused by unpredictable heatwaves have an impact on the food supply chain, as over-estimation of UK supply necessitates costly imports. Temperature extremes are already impacting on quality and supply of tomatoes and peppers, even from countries such as the Netherlands. Retailers, NGO's and consumers are also more aware of the impact on the environment of growing and importing food from unsustainable sources. K&M is a major hub for the UK protected edibles industry, but there is scant UK-based research to support and inform growers' decision-making to mitigate these climate-related impacts.

Studies have shown that even modest increases in vitamin C content can lead to broad tolerance to common abiotic stresses such as salt, cold, ozone, and herbicide treatment. Tomatoes contain only moderate amounts of vitamin C and this depends on genotype, climatic conditions, fruit development, maturation, senescence, and duration of storage. Genetic regulation of vitamin C concentrations in plants can be achieved through the fine-tuning of biosynthetic, recycling, and transport mechanisms. Application of vitamin C effectively primed tomato roots and significantly alleviated heat stress effects on seedlings by reducing oxidative damage and increasing vitamin C, proline contents, and photosynthetic pigments. Iron-nanoparticles can improve iron (Fe) plant uptake, but can also increase plant growth, yield and tolerance to abiotic stresses.

Iron is a key trace-element essential for human health, and a dietary deficiency causes physiological disorders, diseases, and can be fatal, thus constituting a primary global public health challenge. In the UK mean Fe intakes females are below the Reference Nutrient Intake. Increasing the vitamin C content in plants can have a triple-positive effect: producing food with a high content of AsA for human health, increasing postharvest shelf life, and, finally and just as important, increasing the tolerance of plants to various kinds of stresses. By combining vitamin C and Fe biofortification, we will supply the UK market with nutrient-dense tomatoes and enhance Fe bioavailability, while improving the productivity and sustainability of UK tomato production whilst lowering emissions and reducing waste.