CHOICE UNDER STRESS: THE FATE OF STORAGE ROOT DEVELOPMENT UNDER PHOSPHOROUS DEFICIENCY

The storage root is a prime example of a type of specialized organ that can accumulate and store theproducts of photosynthesis allowing plant survival under abiotic stress episodes. When phosphorusavailability is limited, plants use a multifaceted set of strategies to increase the availability of phosphorus in the soil. In sweetpotato, the favorable or lack thereof of storage root development undersuboptimal phosphorus availability is not understood and provides an opportunity for research as a novelstorage root model organism to further our understanding of storage root formation under stress.Recently, we have observed sweetpotato genotypes displaying variable responses to suboptimal phosphorusavailability. The overall objective is to elucidate the mechanisms and the genetic architectureunderlying the reduced secondary root growth of developing roots in sweetpotato. The objectives of this research are to1) measure the extent of reduced secondary root growth and anatomical components that stimulatedecreases in root radial thickening under phosphorus stress, 2) assess the physiological mechanism of rootnon-structural carbohydrate allocation under phosphorus stress, and 3) Identify quantitative trait loci,candidate genes, and gene pathways underlying the natural phenotypic variation in root secondaryroot growth and carbohydrate status.It's crucial to define and understand mechanisms that enhance nutrient stress tolerance to keep American agriculture competitive, end world hunger, and adapt to climate change, which is partof NIFA's grand challenges. Understanding root secondary growth under edaphic nutrient stress could be a game-changer for improving the nutrient stress tolerance of root and tuber crops. Although this project focuses on sweetpotatoes, the findings could be applied to other crops such as cassava, potatoes, sugar beets, and carrots. Therefore, this mechanism may have broad utility in agriculture. By addressing novel scientific issues relevant to human welfare, this project sheds light on the importance of root formation under nutrient stress and offers a new perspective on how to improve crop productivity. The data presented in this project is the first demonstration of the physiological value of these mechanisms under reduced phosphorus availability.