Investigation of oxidative stress responses in Amaranthus with colorimetric assays

Amaranthus species are paradoxically reviled as “superweeds” and revered as “superfoods.” This distinction is a matter of perspective, but it also reflects a suite of shared biological and adaptive traits among species in the genus. Adaptive traits that define some amaranths as aggressive weeds (e.g., prolific seed output, rapid growth, and high tolerance to abiotic stress) can be reframed as valuable agronomic traits for other amaranths grown as pseudocereals or leafy vegetable crops. Cultivated amaranths are recognized for their high nutritional profiles in both seeds and leaves, which are rich in protein, dietary fiber, flavonoids, and vitamins. Weedy amaranth species are notorious for adaptability to a wide range of agricultural settings and evolving herbicide resistance and thus offer excellent case studies for understanding stress response mechanisms. Amaranths are also highly valued as ornamentals due to the added pigmentation trait, expressed in many visually striking patterns in leaves, stems, and floral tissues. Betalains are the principal source of pigmentation in amaranths and are represented by two main classes: betacyanins (red-magenta colors) and betaxanthins (yellow-orange). Betalain pigments have been implicated in possible antioxidant roles in helping amaranths cope with oxidative stress. Still, questions remain regarding their specific roles among diverse pigmented phenotypes and in concert with other plant enzymatic and non-enzymatic antioxidant systems. Greenhouse and laboratory investigations were thus conducted to assess the effects of two stress treatments (i.e., herbicide and drought) on pigmented and non-pigmented weedy and cultivated Amaranthus species using two commonly used colorimetric assays. Specifically, the thiobarbituric acid reactive substances (TBARS) assay and potassium iodide (KI) assay were used to measure two indicators of oxidative stress, malondialdehyde (MDA) and hydrogen peroxide (H2O2), respectively. Protocol optimizations were made for both assays, specifically focusing on betalain pigments as antioxidants and potentially interfering compounds for these color-based assays. Caveats are discussed for each assay, and recommendations are made regarding how these assays should be implemented and interpreted for amaranths and other betalain-producing plants.

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

2022

Author dc:creator

• Woods, James W.

Contributors dc:contributor

• Riggins, Chance W.
• Villamil, Maria B.
• Rodriguez-Zas, Sandra L.

• Amaranthus
• Oxidative Stress
• Lipid Peroxidation
• Malondialdehyde
• Mda
• Herbicide Resistance
• Drought

Statement dc:rights

• Copyright 2022 James Woods

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/117687

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F117687