PS 20-17 - Field inoculation with arbuscular mycorrhizal fungi impacts yield and nutritional quality of potato (Solanum tuberosum)

Abstract: Around 80% of all plants, including most crops, form direct root associations with arbuscular mycorrhizal fungi (AMF), obligate symbiotes of plants which enhance plant soil nutrient acquisition in exchange for photosynthetically derived carbon. Agricultural application of AMF inoculum as a biofertilizer aims to increase the level of root colonization, which in turn enhances plant access to soil nutrients, improves sustainability, and has been deomonstrated to result in yield increases of ~15% for a variety of crops. In addition to the benefit of increased crop productivity, mycorrhizal colonization alters plant physiology and has been shown to increase the level of antioxidants and other beneficial secondary metabolites in edible plant tissues of multiple crops. Due to their popularity and widespread consumption in the United States, and their documented mycorrhizal crop yield response from prior studies, we selected potatoes (Solanum tuberosum) for further evaluation of mycorrhizal impact on nutritional quality through inoculation trials. In a container trial, in addition to the anticipated yield increase ( >20%), we observed a two-fold increase in antioxidant activity and a nine-fold increase in ergothioneine in tubers harvested from mycorrhizal potato plants compared to non-mycorrhizal controls. The latter is a diet-derived antioxidant produced by only fungi and certain bacteria that has recently gained interest for its role in the prevention of age-related diseases in humans. Field trials at two sites were conducted in 2022 to demonstrate that the nutritional benefits of supplemental inoculation translate to field cultivation, in which the inoculations were conducted in the context of indigenous communities of mycorrhizal fungi and other soil microorganisms. These experiments demonstrate how agricultural practices providing benefits to soil health enhance the nutritional quality of food and have implications for improving human health and reducing disease.