Date of Graduation

7-2021

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Plant Science (PhD)

Degree Level

Graduate

Department

Plant Pathology

Advisor

Ken Korth

Committee Member

Martin Egan

Second Committee Member

Vibha Srivastava

Third Committee Member

Andronikos Mauromoustakos

Fourth Committee Member

John Rupe

Keywords

CRISPR gene editing, lipid oxidation, rice (Oryza sativa), rice blast (Magnaporthe oryzae), saponins, text analysis

Abstract

Rice is the staple food for more than half the world’s population, with nearly 500 million metric tons of rice consumed globally every year. Any risk of loss due to disease, waste, or spoilage is therefore noteworthy. This dissertation explores the passage of rice from paddy to pantry to plate, with special attention given to disease and storage life. The most important disease of rice is blast, caused by the ascomycete Magnaporthe oryzae, which can cause losses of ~30% every year. This study found that saponin-enriched root extracts of Medicago truncatula effectively kill fungal spores in vitro and reduce moderate disease in planta. After harvest and processing, milled white rice has a very long shelf life whereas brown rice may become rancid in less than a year due to the high proportion of lipids in its bran layer. This research produced moderate improvements in brown rice shelf life by using CRISPR gene editing to modify a lipase and lipoxygenase gene expressed in the bran layer. Finally, text analysis was used to qualitatively and quantitatively explore global rice cuisine as compiled in a crowd-sourced format on Wikipedia, revealing commonalities among countries and regions as well as significant gaps in the data. The multidisciplinary research reported here advances the goals of improved rice blast disease control and brown rice quality, and describes cultural preferences of this staple crop in statistical detail, with the ultimate aim of supporting sustainable, affordable access to rice worldwide.

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