University of Illinois Urbana-Champaign

Investigation of oxidative stress responses in Amaranthus with colorimetric assays

Woods, James W.

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

Description

Title
Investigation of oxidative stress responses in Amaranthus with colorimetric assays
Author(s)
Woods, James W.
Issue Date
2022-12-08
Director of Research (if dissertation) or Advisor (if thesis)
Riggins, Chance W.
Committee Member(s)
  • Villamil, Maria B.
  • Rodriguez-Zas, Sandra L.
Department of Study
Crop Sciences
Discipline
Crop Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
M.S.
Degree Level
Thesis
Keyword(s)
  • Amaranthus
  • oxidative stress
  • lipid peroxidation
  • malondialdehyde
  • MDA
  • herbicide resistance
  • drought
Abstract
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.
Graduation Semester
2022-12
Type of Resource
Thesis
Copyright and License Information
Copyright 2022 James Woods

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