Recipient Organization
UNIVERSITY OF ILLINOIS
2001 S. Lincoln Ave.
URBANA,IL 61801
Performing Department
Crop Sciences
Non Technical Summary
Species in the genus Amaranthus (Amaranthaceae) are primarily herbaceous annuals commonly found intropical to warm-temperate zones. The majority of species are native to the Americas, where some havebeen cultivated as pseudocereal and/or leafy vegetable food crops for millennia. Despite their history ofuse, however, amaranths are often classified as "neglected and underutilized" crops given the general lackof research and limited breeding efforts compared to other major crops. Cultivated amaranths are notablefor their high nutritional value, palatability, and versatility as ingredients for an expanding market of foodand cosmetic products. Favorable agronomic characteristics (e.g., rapid growth rates, C4 photosynthesis,and high tolerance to drought, heat, and salinity) also make amaranths appealing crops for agriculturallymarginal lands. These same traits, however, are also shared with weedy amaranth species, some of whichhave rapidly risen to become among the most economically-damaging weeds in U.S. agriculture. Weedyamaranths are notable for their rapid adaptive evolution to ever-changing weed management regimes in avariety of crop production systems and for evolving resistance to herbicides. This duality betweenpromising crops and pernicious weeds makes amaranth species exceptional, yet underexploited, modelsfor connecting fundamental and applied research; a link with substantial economic and agronomic implications.Little genetic improvement of amaranth has been achieved and relatively few traits have beencharacterized at the molecular and genetic level. Some evidence, however, from our previous work andotherssuggests that genes linked to pigment biosynthesis (betalains andcarotenoids) may possess diverse functions associated with plant stress response and herbicidedetoxification. Betalains are a class of plant pigments responsible for the brilliant yellow and red-violetcolors of plants in the order Caryophyllales, which includes amaranth along with quinoa, spinach, redbeets, and cacti. As nitrogenous-based pigments, betalains are biosynthetically distinct fromanthocyanins, the predominant class of plant pigments, and both groups are mutually exclusive inoccurrence. Unlike anthocyanins, less is known about betalain biosynthesis pathways, genes, andregulation, yet betalains are known to possess high free radical scavenging activities. For this reason, betalains have been exploited as antioxidants and natural food colorants inapplications not suitable for anthocyanins. Red beets are the primary commercial source of betalains, butbeets can impart an undesirable flavor to foods. Alternative sources for betalains have received scarceattention in comparison to beets, which have long been considered the only edible commercial source.Investigating betalains in Amaranthus will lead to new knowledge of their biochemistry, distribution, andfunctional roles, and improve understanding of agronomic and adaptive traits in the genus. Thisknowledge, in turn, will lead to a value-added assessment of the commercial potential of betalains fromamaranth as natural food colorants.
Animal Health Component
35%
Research Effort Categories
Basic
35%
Applied
35%
Developmental
30%
Goals / Objectives
1. Identify and characterize genes and enzymes involved in betalain biosynthesis in Amaranthus.2. Improve extraction and analytical protocols used to survey phytochemical diversity within the genus,with primary focus on pigments (betalains and carotenoids) and other constituents of nutritional andcommercial significance, such as oxalates, nitrates, and saponins.3. Identify top-performing pigmented cultivars and test stability of pigment extracts following foodindustry standards.4. Integrate phytochemical data with other available datasets (e.g., genomic, transcriptomic,metabolomic) to guide future studies pertaining to stress response and adaptive evolution in weedyand cultivated amaranth species.
Project Methods
The objectives of this proposal are best met using an integrative approach that combines molecular-basedlaboratory analyses with field and greenhouse experiments, and that includes wild, weedy, and cultivatedamaranth species. In addition to herbicide target genes, our focus will expand to determine the structure,copy number, and other characteristics of genes involved directly or indirectly in betalain biosynthesis(Objective 1). We will use in-house genomic and transcriptomic datasets developed from studies ofweedy species along with publically-available amaranth genomic resources to facilitate molecular marker development and characterization of known genesand putative candidate loci for biosynthesis and transport.As water-soluble pigments, betalains are easily obtained by conventional solid-liquid extraction methodswith aqueous solvents (Objective 2). Betalain content and composition will be determined viaspectrophotometric and HPLC analyses. When needed, mass spectroscopy and NMR techniques will beemployed for structure elucidation. Protocols for extraction, isolation, and elucidation of carotenoids,oxalates, nitrates, and saponins in amaranth are currently under development. One additionalconsideration is the choice of extraction and processing method on yield, stability, and subsequentstructure determination, especially with regard to food industry standards. Chemical procedures for exploring functional or adaptive roles of amaranth compounds may notnecessarily be the same methods applied to research commercial food applications. To exploit amaranthbetalains for commercial purposes, and comply with current Good Manufacturing Practices, we willrefine extraction methods to study pigment loss and stability.We will continue with our chemical surveys and greenhouse trials to test additional vegetable amaranthcultivars and species for betalain production (Objective 3). Genotypes with high foliar betacyanin contentwill be selected for stability analyses. We will continue to test amaranth accessions obtained from theNorth Central Regional Plant Introduction Station, plus commercial suppliers andwild/weedy types from our own germplasm collection. Greenhouse and field-grown plants will be grownat the University of Illinois. Since we are interested in both baseline phytochemical data and generatingbasic information on factors potentially influencing pigment production and yield, our plan will be toharvest aboveground biomass sequentially at 7, 14, and 21 weeks after sowing. Stem and leaf tissue > 10cm above ground level will be harvested and lyophilized. Dried materials will then be ground to a powderand stored at -20 °C until extraction. Extracts from red table beets will be used for comparison. Thestability of extracts from highly pigmented amaranth cultivars will be tested in a model beverage systemin conjunction with control beet extracts at multiple pH values and temperatures. A UV-Vis spectrophotometer and tintometer will be used to quantify color characteristics such as intensity,hue, and saturation as the extracts degrade over time.Objective 4 represents synthesis of results from this research with prior findings and ongoingcollaborations with cooperating partners across multiple disciplines with the long-term aim to developimproved tools for breeding and characterizing sources of variation and mechanisms involved in theadaptive evolution of Amaranthus. As stated, betalains lie at the intersection of questions pertaining to plant oxidative stress response, phytochemicals for human nutrition, and herbicide detoxificationmechanisms, and insights from Objectives 1-3 will create a foundation for targeted studies in these areas. Findings from this research will benefit plant scientists in academia and industry with interests spanningphysiology, biochemistry, food science, and agricultural weed management.