Date of Award

12-15-2014

Document Type

Open Access Dissertation

Department

Biological Sciences

First Advisor

Stephen Kresovich

Abstract

Staple cereal crops provide the majority of nutrients to the world's population, and thus, can significantly impact human nutrition and health. Phenotypic and genetic diversity within a crop can be useful for biofortification and crop improvement, but quantitative phenotyping is needed to identify varieties with high or low concentrations of a nutrient of interest, and to identify alleles responsible for quantitative trait variation of the nutrient. Sorghum [Sorghum bicolor (L.) Moench] is a diverse and widely adapted cereal crop that provides food for more than 500 million people in sub-Saharan Africa and Asia, and is becoming increasingly popular in specialty grain products in the United States. Sorghum is a valuable resource for nutrient diversity, as adaptation to different environments has led to extensive phenotypic and genetic diversity in the crop. Many sorghum varieties are rich in flavonoids, primarily 3-deoxyanthocyanidins and proanthocyanidins, which appear to protect against chronic inflammatory diseases. Most studies have only explored the health benefits of a small number of sorghum accessions, but over 45,000 sorghum accessions exist in crop gene banks. A large genetically diverse sorghum panel can be used to identify varieties with high concentrations of flavonoids and to explore the effects of natural variation of sorghum flavonoids on inflammation. This same resource can also be used to identify varieties with high concentrations of protein, fat, or starch, which can lead to improved nutritional value of sorghum grain.

The overall aim of my dissertation project was to quantify sorghum flavonoids and identify allelic variants controlling them; quantify grain composition more broadly (protein, fat, and starch) and identify allelic variants controlling them; and investigate anti-inflammatory properties of sorghum extracts with contrasting levels of flavonoids. Using a large germplasm resource (USDA National Plant Germplasm System), highthroughput methods of phenotyping (near-infrared spectroscopy) and genotyping (genotyping-by-sequencing), association mapping (genome-wide association studies), and in vitro inflammation models, the work presented here provides new insights into the diversity, genetics, and anti-inflammatory properties of sorghum nutrients that are important to human health. It provides a survey of grain nutrient diversity in a large global panel of sorghum, identifies quantitative trait loci and candidate genes for underlying controls of these nutrients, and demonstrates that a larger variety of sorghum accessions than previously thought have anti-inflammatory properties.

Rights

© 2014, Davina Rhodes

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