Transcriptomic analysis of metabolic processes in near-isogenic and inbred purple corn pericarp

Anthocyanins are naturally occurring plant pigments characterized by water-soluble and antioxidative properties. Compared to other natural pigments that require harsh, organic solvents for extractions, anthocyanins are simpler and cheaper to extract. Their antioxidative properties play key roles in a plant’s defense response against oxidative stress. Much research has gone into their propensity towards health-promoting, protective benefits when incorporated into human diets, including anti-cancer and anti-inflammatory effects. Public interest for healthier alternatives to carcinogenic, synthetic food dyes has prompted research into anthocyanins as potential sources of natural food colorants. Anthocyanin-producing, staple food crops, such as purple corn, are excellent sources of anthocyanins that meet Food and Drug Administration (FDA)-approval for use in human consumption. Introducing purple corn into the Midwestern Corn Belt, the top producer of corn worldwide, can easily integrate anthocyanin production into pre-existing, large-scale corn production. Purple corn is a value-added crop with multiple uses as food, feed, and fuel, in addition to natural food colorants. Of the edible corn kernel tissues, the pericarp layer accumulates the highest concentration of anthocyanins, making it a breeding target for anthocyanin content optimization. Anthocyanin biosynthesis has been well-characterized in maize aleurone, yet the entire anthocyanin biosynthetic pathway has yet to be validated in pericarp. While conservation of the biosynthetic pathway is expected between tissues, various tissue-specific genes are known to function in pericarp anthocyanin biosynthesis. To identify influential genes involved in anthocyanin accumulation during pericarp development, RNA-sequencing (RNA-seq) was conducted on whole pericarp tissue from near-isogenic and inbred pericarp-pigmented corn lines (B73 Color Converted, Amazonas, and Maize Morado) harvested at 10, 15, and 20 days after pollination (DAP). Ultra High-Performance Liquid Chromatography (UHPLC) analysis of whole kernels quantified increasing anthocyanin content (mg/kernel) between 10 and 20 DAP. Specifically, we found a significant increase in anthocyanin content between 15 and 20 DAP in Amazonas and Maize Morado. In a follow-up study where an additional pigmented, near-isogenic line was included (Mo17 Color Converted), whole pericarp tissue was harvested at 18 DAP and divided into pigmented and unpigmented fractions for RNA-seq analysis to supply a more appropriate negative control. Comparative transcriptomic analysis of pigmented and unpigmented pericarp collected from the same kernels provides a high-resolution comparison of the processes involved in pericarp pigmentation. Candidate genes identified at 18 DAP may be responsible for the spike in anthocyanin content observed between 15 and 20 DAP. Overall, our studies identified candidate genes related to elevated anthocyanin content in maize pericarp, which have potential application in breeding programs through marker-assisted selection.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Crop Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2024

Author dc:creator

• Anderson, Holly

Contributors dc:contributor

• Juvik, John A
• Studer, Anthony J
• Rutkoski, Jessica E

• Anthocyanin
• Corn
• Pericarp
• Rna-sequencing

Statement dc:rights

• Copyright 2024 Holly Anderson

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/125732

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F125732