Anthocyanin Variation Research Articles

Application of poly(L-lactic acid)-based films for equilibrium modified atmosphere packaging of “Kyoho” grapes and its favorable protection for anthocyanins

Grapes were packaged by different Poly (L-lactic acid)-based packaging films (PLTL-PLEL) and stored at 5 °C for 35 days to investigate the effects of equilibrium modified atmosphere packaging on the quality of “Kyoho” grapes during storage. Changes in physiochemical quality, antioxidant content and senescence of grapes were studied. Furthermore, UPLC-Q-TOF-MS/MS was used to observe and identify key factors influencing the variation of grape anthocyanins under different atmosphere conditions. Alterations in gas components and enzyme activities significantly impacted anthocyanin levels, highlighting oxygen concentration as the primary influence on total anthocyanin levels. The PLTL-PLEL50 packaging resulted in an approximate 5.7% lower weight loss and increased soluble solids by approximately 14.4%, vitamin C, total phenols and flavonoids reaching 60.2 mg/100 g, 8.4 mg/100 g and 7.2 mg/100 g, respectively. This packaging also preserved higher anthocyanin levels, with malvidin-3-glucoside and peonidin-3-glucoside at 0.55 μg/mL and 1.62 μg/mL, respectively, on the 35th day of storage.

Study of UV–Vis molar absorptivity variation and quantitation of anthocyanins using molar relative response factor

The effects of anthocyanin’s substitution groups on the UV–Vis molar absorptivity were examined by analyzing a group of 31 anthocyanidin/anthocyanin reference standards with ultra-high performance liquid chromatography-diode array detector (UHPLC-DAD). The substitution groups on aglycones were found to associate with molar absorptivity variations, often neglected in anthocyanin quantitation, resulting in significant analytical errors. A simple yet comprehensive strategy based on the molar relative response factors (MRRFs) and a single master reference calibration (i.e., cyanidin-3-glucoside) was proposed to quantify anthocyanins in red cabbage, blueberry, and strawberry samples with improved analytical accuracy. The results indicate this approach provides an effective, inexpensive, and accurate analytical method for anthocyanins in food materials without using individual reference standards. MRRFs of 617 anthocyanins/anthocyanidins were calculated, and the information is freely available at https://BotanicalDC.online/anthocyanin/. This study could be critical to developing new reference methods for anthocyanin analysis and harmonizing results and data from various sources.

Does an R2R3-MYB transcription factor affect anthurium spathe colour variation via regulation of vacuolar pH?

The anthurium is a popular cut flower worldwide having red, pink, coral, white, green, or brown spathes. There is a constant demand for new flower colours in the commercial market. Flower colour in plants is mainly determined by anthocyanins. Understanding anthocyanin variation and other factors affecting anthurium spathe colour is important for genetic engineering approaches. Therefore, our objectives were to assess the factors affecting colour variation of selected commercially available cut flower anthuriums and to determine the associated regulatory networks and transcription factors (TFs). Nineteen commercial cut flower anthurium cultivars were selected for this purpose. The colour of the spathe surface, anthocyanin location, anthocyanidin type and vacuolar pH were recorded. Anthocyanin associated Gene Network Model generation and analysis were carried out. The CIELAB colourimeter procedure indicated the colour variation among the selected 19 cultivars in terms of colour type, colour intensity, chroma, and hue angle. The location of anthocyanin was limited to mesophyll and epidermal cells. Cyanidin was detected in tested anthurium cultivars as the main anthocyanidin. The pH gradient in pigment extracts indicated a variation with a range of 4.6 to 4.94. The gene pathways of anthocyanin biosynthesis and transport were associated with that of the vacuolar pH/H+ pump according to Gene Network Model. Three pathways were regulated by an R2R3-MYB transcription factor. Although, cyanidin was the only pigment in all the tested cultivars, different pH levels by R2R3-MYB regulated V-H+ synthase was suggested to be the cause of the high colour variation in addition to the anthocyanidin type and location. Our results indicate the application of R2R3-MYB transcription factor genes for desirable vacuolar pH maintenance in genetic engineering of the blue anthurium in the future.

Variation of chemical and sensory profiles of blackcurrant (Ribes nigrum) juices produced from different cultivars of European origins

Blackcurrant cultivars originating from different European countries (Finland, Latvia, Lithuania, Poland, and Scotland) but cultivated at the same geographic location and under the same climatic conditions in Finland were investigated. Berries of 21 cultivars were pressed into juices without enzymatic assistance, and the chemical and sensory profiles were studied. The genotype significantly influenced juice yield (47–70% of berry weight), anthocyanin profile (including 42–64% of delphinidins and 32–54% of cyanidins; rutinosides vs. glucosides, 3–9:1), and sensory properties of the juice (appearance, flavor, and mouthfeel). The studied cultivars exhibited a large diversity in anthocyanin content in berries (904–4595 μg/g of berries), juices (obtained by pressing pulps, 141–1028 μg/g of juices), and press residues (skins and seeds, 3492–19852 μg/g of residues). Variation of anthocyanins in juices was unrelated to the variation in berries. The perceived color was affected by the anthocyanin contents in juices but not by the anthocyanin levels in berries. These measured compounds did not have a direct association with viscosity, flavor, or aftertaste of the juices.

The variation of total flavonoids, anthocyanins and total phenols in Vaccinium uliginosum fruits in Changbai Mountain of China is closely related to spatial distribution

BACKGROUND: The fruit of Vaccinium uliginosum is a natural berry resource that is rich in polyphenols, flavonol glycosides, anthocyanins, and other active substances, indicating its high developmental potential. However, research on V. uliginosum is limited, with no literature available to clarify the germplasm resources suitable for breeding. OBJECTIVE: This study aimed to evaluate the contents of total flavonoids (TF), total anthocyanins (TA), and total phenols (TP) in 10 different populations of V. uliginosum from the Changbai Mountains, China, and investigate the correlation between these functional components and spatial distribution. METHODS: The components and contents of TA, TF, and TP were determined using mass spectrometry, high-performance liquid chromatography, and the Folin–Ciocalteu method, respectively. RESULTS: A total of 15 anthocyanins were detected, and the content of Mal-glu, Pet-glu, and Del-glu was the highest among these anthocyanins. The TF and TA and TP contents were highest in the DFHI and LJII populations, respectively, which can be reasonably developed as excellent populations. The TF content of sample DFHI-8, TA content of LJIII-1 and TP content of LJIII-4 were higher than other samples, which can be used as important breeding germplasm. The content of TF is positively correlated with altitude, while the content of TA and TP is bidirectional, which is positively correlated at 740–838 m and negatively correlated at >838 m. CONCLUSIONS: Significant differences in the contents of TF, TA, and TP in V. uliginosum fruit were found among and within populations, and there was a certain correlation between these contents and their spatial distribution.

Integrated transcriptomic and metabolic analyses unveil anthocyanins biosynthesis metabolism in three different color cultivars of grape (Vitis vinifera L.)

Anthocyanins as plant pigments are responsible for the color of the grape berry. The major concern among consumers is color, quality, and appearance, therefore, skin color is the most important item that affects consumer purchases. In this study, we used three grape cultivars namely Red globe (bright red), Kyoho (purple-red), and Wink (purple-black), and evaluated color changes in three different developmental stages according to time course including 15 days after the berry color shift from green to red (V1), 25 days after the berry color shift from green to red (V2), and 35 days after the berry color shift from green to red (V3). The dynamic changes in anthocyanin content and components were detected using "High-Performance Liquid Chromatography mass spectrometry/mass spectrometry (HPLC-MS/MS)" technology. Furthermore, we performed transcriptome sequencing and identified the genes involved in the anthocyanin biosynthesis and accumulation in grape berry development. In total, we detected 13 different anthocyanin components in three grape cultivars. Malvidin, petunidin, and delphinidin derivates are the main components of dark colored grape (Kyoho and Wink), while cyanidin and pelargonidin derivates are the sources of bright-colored grape (Red globe). According to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, many DEGs were enrichment in phenylpropanoid biosynthesis and flavonoid biosynthesis. We also found thirty-nine DEGs to be involved in the anthocyanin metabolism and accumulation. Furthermore, using weighted gene correlation analysis (WGCNA), three modules (blue, magenta, and tan) and nineteen hub genes were highly correlated with anthocyanin variation. Our research provided new insights for elucidating the anthocyanin metabolic pathway and related genes, signal perception and transduction during grape berries development at different stages.

Variation of Anthocyanin, Phenol, and Antioxidant Capacity in Straw among Rice Varieties and Growing Locations as a Potential Source of Natural Bioactive Compounds.

This study evaluated the variation in bioactive compounds (anthocyanins, phenols, and antioxidants) among 22 rice varieties in the same growing locations and among four varieties collected from eight different provinces in Northern Thailand. Wide variation in anthocyanins, phenols, and antioxidant capacity was established, ranging from 1.6 to 33.0 mg/100 g, 249.9 to 477.7 mg gallic acid/100 g, and 0 to 3,288.5 mg trolox equivalent/100 g, respectively. The highest straw anthocyanin and phenol concentrations were found in KDK (a traditional photoperiod-sensitive variety with purple pericarp and leaves) and K4 (an advanced, photoperiod-insensitive variety with purple pericarp and leaves), while the highest antioxidant capacity was found in KH CMU (an improved traditional photoperiod sensitive variety with a purple pericarp and green leaves) and K4. The variation of the bioactive compounds was also found in the same variety grown at different locations, e.g., the KDMl105 grown in Prayao province had a straw anthocyanin concentration higher than when grown in Mae Hong Son province. The effect was also observed in phenol content and antioxidant capacity when the same rice variety was grown across various locations. A significant correlation between total phenol and antioxidant capacity was observed across rice varieties and growing locations but was not found between anthocyanin and antioxidant capacity. This study found that the bioactive compounds in rice straw varied among rice varieties and growing locations. Straw phenol acts as a major antioxidant that can be used as a characteristic for the selection of rice varieties with high antioxidant capacity for use at the industrial scale for the processing of food, pharmaceuticals, and medicinal products.

Effects of ethephon and low-temperature treatments on blood oranges (Citrus sinensis L. Osbeck): Anthocyanin accumulation and volatile profile changes during storage

Health-promoting anthocyanins in blood oranges can be enriched via appropriate postharvest storage conditions. Here, we explored the changes of anthocyanin accumulation and volatile profiles of Tarocco blood oranges (Citrus sinensis L. Osbeck) treated by the low temperature alone and combined with ethephon (2 mg/mL) during 50 days of storage. The combination treatment of ethephon and low temperature (8 oC) significantly enhanced the levels of total anthocyanins (10.91 ± 0.25 mg/100 g) and individual cyanidin derivatives relative to low-temperature treatment alone. The increases of six cyanidin derivatives and three delphinidin derivatives identified by LC-MS/Q-TOF were consistent with the variation in total anthocyanins. Ethyl butanoate, ethyl 2-methylbutyrate, ethyl hexanoate, ethyl undecanoate, linalool, and d-limonene were identified as main contributors to overall aroma of fresh blood oranges. Volatile compositions and concentrations were decreased under different treatments of ethephon and temperatures, while ethephon could alleviate the loss of activity volatiles during cold storage.

Genome-Wide Analysis of the Glutathione S-Transferase (GST) Genes and Functional Identification of MdGSTU12 Reveals the Involvement in the Regulation of Anthocyanin Accumulation in Apple.

Anthocyanins have essential biological functions, affecting the development of horticultural production. They are synthesized in the cytoplasm through flavonoid metabolic pathways and finally transported into vacuoles for storage. Plant glutathione S-transferases (GSTs) are multifunctional enzymes involved in anthocyanin transportation. In this study, we identified 38 GSTs from the apple (Malus domestica) genome (HFTH1 Whole Genome v1.0) based on the sequence similarity with the GST family proteins of Arabidopsis. These MdGST genes could be grouped into nine chief subclasses: U, F, L, Z, T, GHR, EF1Bγ, TCHQD, and DHAR. The structures, motifs, three-dimensional models, and chromosomal distribution of MdGST genes were further analyzed. Elements which are responsive for some hormones and stress, and others that involve genes related to flavonoid biosynthesis were forecast in the promoter of MdGST. In addition, we identified 32 orthologous gene pairs between apple and Arabidopsis. These genes indicated that numerous apple and Arabidopsis counterparts appeared to be derived from a common ancestor. Amongst the 38 MdGST genes, MdGSTU12 was considerably correlated with anthocyanin variation in terms of extracting expression profiles from reported. Finally, further functional identification in apple transgenic calli and subcellular localization confirmed that MdGSTU12 was of great significance in anthocyanin accumulation in apple.

스위트 오렌지 ‘Cara cara’, ‘Moro’, ‘Tarocco’의 성분 분석과 항산화 활성

This paper reports on the composition of pigment compound in three cultivars 'Cara Cara’, 'Moro', and 'Tarocco’ of Citrus sinensis. The present study investigated the variation in anthocyanins, carotenoids, total polyphenol, and flavonoids, and antioxidant activity in peel and flesh of C. sinensis. The flavonoid and carotenoid compositions were campared with HPLC method. TA content were highest in ‘Moro’ flesh (17.179 mg/100 g). TC were highest in Tarocco peel(17.087 mg/100g) and β -cryptoxanthine were highest in ‘Tarocco’ flesh(439 ug/100 g). TF were highest in ‘Cara Cara’ peel (209.2 mg/100 g) and all cultivar materials had high levels of hesperidin(‘Cara Cara’ 3.32 g/100 g; ‘Moro’, 2.012 g/100 g; ‘Taroco’, 2.06 g/100 g). These components had the highest antioxidant activity in the ‘Cara Cara’ peel, which had the highest flavonoid content in ABTS radical scavenging activity, as these components had an effect on antioxidant activity. When ‘Cara Cara’ peel extract was treated with 250 ug/mL, more than 70% of the radical scavenging activity could be measured. Therefore, these results suggest that fruits of ‘Cara Cara’, “Moro’, and ‘Tarocco’ are significant sourcse of antioxidant compounds such as phenolics, flavonoid, and β -cryptoxanthin.

Pathway-based analysis of anthocyanin diversity in diploid potato.

Anthocyanin biosynthesis is one of the most studied pathways in plants due to the important ecological role played by these compounds and the potential health benefits of anthocyanin consumption. Given the interest in identifying new genetic factors underlying anthocyanin content we studied a diverse collection of diploid potatoes by combining a genome-wide association study and pathway-based analyses. By using an expanded SNP dataset, we identified candidate genes that had not been associated with anthocyanin variation in potatoes, namely a Myb transcription factor, a Leucoanthocyanidin dioxygenase gene and a vacuolar membrane protein. Importantly, a genomic region in chromosome 10 harbored the SNPs with strongest associations with anthocyanin content in GWAS. Some of these SNPs were associated with multiple anthocyanin compounds and therefore could underline the existence of pleiotropic genes or anthocyanin biosynthetic clusters. We identified multiple anthocyanin homologs in this genomic region, including four transcription factors and five enzymes that could be governing anthocyanin variation. For instance, a SNP linked to the phenylalanine ammonia-lyase gene, encoding the first enzyme in the phenylpropanoid biosynthetic pathway, was associated with all of the five anthocyanins measured. Finally, we combined a pathway analysis and GWAS of other agronomic traits to identify pathways related to anthocyanin biosynthesis in potatoes. We found that methionine metabolism and the production of sugars and hydroxycinnamic acids are genetically correlated to anthocyanin biosynthesis. The results contribute to the understanding of anthocyanins regulation in potatoes and can be used in future breeding programs focused on nutraceutical food.

Chromosome-Level Genome Assembly of the American Cranberry (Vaccinium macrocarpon Ait.) and Its Wild Relative Vaccinium microcarpum.

The American cranberry (Vaccinium macrocarpon Ait.) is an iconic North American fruit crop of great cultural and economic importance. Cranberry can be considered a fruit crop model due to its unique fruit nutrient composition, overlapping generations, recent domestication, both sexual and asexual reproduction modes, and the existence of cross-compatible wild species. Development of cranberry molecular resources started very recently; however, further genetic studies are now being limited by the lack of a high-quality genome assembly. Here, we report the first chromosome-scale genome assembly of cranberry, cultivar Stevens, and a draft genome of its close wild relative species Vaccinium microcarpum. More than 92% of the estimated cranberry genome size (492 Mb) was assembled into 12 chromosomes, which enabled gene model prediction and chromosome-level comparative genomics. Our analysis revealed two polyploidization events, the ancient γ-triplication, and a more recent whole genome duplication shared with other members of the Ericaeae, Theaceae and Actinidiaceae families approximately 61 Mya. Furthermore, comparative genomics within the Vaccinium genus suggested cranberry-V. microcarpum divergence occurred 4.5 Mya, following their divergence from blueberry 10.4 Mya, which agrees with morphological differences between these species and previously identified duplication events. Finally, we identified a cluster of subgroup-6 R2R3 MYB transcription factors within a genomic region spanning a large QTL for anthocyanin variation in cranberry fruit. Phylogenetic analysis suggested these genes likely act as anthocyanin biosynthesis regulators in cranberry. Undoubtedly, these new cranberry genomic resources will facilitate the dissection of the genetic mechanisms governing agronomic traits and further breeding efforts at the molecular level.

Variation in anthocyanins of different varieties of purple carrots

The composition and content of anthocyanins were investigated in nine varieties of purple carrots to reveal the diversity of the anthocyanins among different varieties of purple carrots. The results showed the significant differences of the composition and content of anthocyanins were found between nine varieties of purple carrots. Five anthocyanins were detected in purple carrots, including cyanidin 3-xylosyl(glucosyl), cyanidin 3-xylosylgalactoside, cyanidin 3-xylosyl (sinapoylglucosyl)galactoside, cyanidin 3-xylosyl(feruloylglucosyl)galactoside, and cyanidin 3-xylosyl(coumaroylglucosyl)galactoside. Only four of the five anthocyanins were detected in Caohaihong, Zhongzidan, and Yanzi, whereas 3-xylosyl(coumaroylglucosyl)galactoside were not detected. The highest content of total anthocyanins was found in Tianzi. In addition, the highest contents of individual anthocyanins except for cyanidin 3-xylosyl(sinapoylglucosyl)galactoside, were also in Tianzi, and the highest content of 3-xylosyl(sinapoylglucosyl)galactoside was found in Zishengzi. In summary, these findings provide a theoretical reference for the scientific consumption and a foundation for the further study of purple carrots in the future.

Genome-wide analysis of auxin response factor (ARF) genes and functional identification of MdARF2 reveals the involvement in the regulation of anthocyanin accumulation in apple

ABSTRACT Auxin response factors (ARFs) mediate auxin response gene transcription by directly binding with AuxREs. However, whether ARF family genes involved in anthocyanin accumulation in apple is largely unexplored. In this study, thirty-three MdARF family members were identified in the apple (Malus × domestica) genome (HFTH1 Whole Genome v1.0) based on the sequence similarity with ARF family members of Arabidopsis. Phylogenetic analysis revealed that thirty-three MdARF members were clustered into Class I, Class II and Class III. Functional domain analysis showed that MdARF proteins have some typical domains such as B3-like DNA-binding domain and Auxin_resp domain, as well as motif III and motif IV. Chromosome localisation analysis demonstrated that apple ARF members were widely distributed in the genome. Among these MdARF genes, MdARF2 was significantly correlated with anthocyanin variation according to extracting expression profiles from published RNA-seq data. Further functional identification in apple calli suggested that MdARF2 functions as a transcriptional repressor of anthocyanin biosynthesis. These findings provide evidence that MdARF family members play a role in the regulation of anthocyanin accumulation in apple.

Erratum: Parra-Galindo, M.A., et al. Chromosomes I and X Harbor Consistent Genetic Factors Associated with the Anthocyanin Variation in Potato Agronomy 2019, 9, 366

The authors would like to make the following correction to the published paper [...]

Leaf resistance traits influence endophytic fungi colonization and community composition in a South American temperate rainforest

Abstract Despite the ubiquitous presence of fungal endophytes in woody plants, mechanisms underlying variation in foliar fungal endophyte communities are poorly understood. Given that endophytes in woody plants are predominantly horizontally transmitted, fungal endophyte colonization of foliar tissues is likely to be influenced by plant resistance traits. Here, we evaluated the association between leaf resistance traits and colonization and community composition of horizontally transmitted endophytes (HTE) in 10 dominant trees species in a temperate rainforest in Southern Chile. Because resistance traits might restrict colonization of HTE, it was hypothesized that host trees with similar leaf resistance traits would show similar HTE communities. We measured leaf traits with reported roles in plant resistance against pathogens and/or herbivores: cell wall polysaccharides, leaf toughness, flavonoids, anthocyanins, terpenoids and chitinases. We also determined variation in fungal read counts, number of operational taxonomic units (OTUs), diversity and community structure across tree species. Foliar fungal endophyte communities were characterized using Illumina MiSeq sequencing of tagged amplicons of the ITS1 region. Fungal read counts were significantly different among host trees, while number of OTUs and diversity were similar among them. Multivariate analyses showed that community composition of endophytic fungi significantly differed among hosts, and that variation in cell wall, flavonoids, anthocyanins and terpenoids was associated with differences in HTE communities. We found that host trees sharing leaf resistance traits harbour similar HTE communities. Fungal read counts decreased with increasing content of cell wall polysaccharides, while endophyte diversity decreased with increasing anthocyanin levels. Fungal read counts, in contrast, were positively associated with terpenoids. Additionally, culture‐based data indicated that some HTE strains inhibited the growth of the common fungal pathogen Botrytis cinerea. Synthesis. Overall, we found that leaf resistance traits may influence fungal endophyte colonization and community composition in tree species, likely through deterrent effects of structural and chemical traits. We suggest that endophytic fungi that overcome resistance traits might play a role in plant protection.

Chromosomes I and X Harbor Consistent Genetic Factors Associated with the Anthocyanin Variation in Potato

Potatoes are an important staple food worldwide and are the third main source of antioxidants in the human diet. One of the most important antioxidant compounds in potatoes is the anthocyanin pigments. Some reports indicate a high positive correlation between color intensity, anthocyanins content, and antioxidant level in potato tubers. The variation in anthocyanins composition and content in potato tubers among diverse germplasm sources has important nutritional and health implications and constitutes an interesting trait for potato breeding programs focused on enhancing the anthocyanin and antioxidant contents of potato materials. We identified and quantified five anthocyanidins (delphinidin, cyanidin, petunidin, pelargonidin, and peonidin) on tubers from the Colombian germplasm collection of Solanum tuberosum L. Group Phureja. The phenotypic data were merged into a genome-wide association study in order to identify genomic regions associated with the nutritional compounds’ variation in potatoes. The association was conducted using a 7520 single nucleotide polymorphisms markers matrix. Seven quantitative trait loci were identified. Chromosomes I and X harbored the most stable quantitative trait loci (QTL). Three quantitative trait loci were identified close to previously reported genes involved in the regulation of anthocyanins in potato tubers. The genomic regions of these QTL reveal presumptive candidate genes as genetic factors that are the basis for a better understanding of the genetic architecture of the regulation of nutritional compounds in potatoes.

Effect of domestic cooking methods on the anthocyanins and antioxidant activity of deeply purple-fleshed sweetpotato GZ9

Purple-fleshed sweetpotatoes (PFSPs) are considered to be a healthy food and there are many methods to process in family. This study aimed to investigate the effects of various domestic cooking on the anthocyanin variation and antioxidant activity of a newly bred purple-fleshed cultivar Guangzishu 9 (GZ9) with anthocyanin content up to 1,500 mg/100g dry weight. As a result, total 15 individual anthocyanins were separated and identified by using UPLC-QTOF-MS. Top three anthocyanins were cyanidin 3-dicaffeoyl sophoroside-5-glucoside, cyanidin 3-caffeoyl- p-coumaryl sophoroside-5-glucoside and peonidin 3-caffeoyl-p-hydroxybenzoyl sophoroside-5-glucoside, which accounting for 57.27% of the total anthocyanin content. Acylated anthocyanins were the major constituents in GZ9, and the type of anthocyanins was dominated by cyanidin. Boiling, steaming and mircrowaving had no significant effect on the total anthocyanin content. But baking, frying, air-frying and stir-frying reduced 11–45% of total anthocyanin content. Through ABTS+ radical scavenging capacity and reducing power, antioxidant variations were also observed during different family cooking, and the variation had a strong correlation with total anthocyanin content.

Variation of Anthocyanins, Proanthocyanidins, Flavonols, and Organic Acids in Cultivated and Wild Diploid Blueberry Species

The flavonoid and organic acid profiles of one cultivated tetraploid and six wild diploid blueberry species (Vaccinium spp.) were systematically investigated using high-performance liquid chromatography–electrospray ionization–tandem mass spectrometry (HPLC-ESI-MS-MS). Eighteen individual anthocyanins from five aglycone classes were characterized among species, with malvidin and delphinidin glycosides accounting for 31.4% and 29.1% of total anthocyanins. Twenty-three flavonol glycosides from six aglycone classes were identified, among which quercetin and myricetin glycosides accounted for more than 80% of total flavonols in most species. Both inter- and intraspecies differences in anthocyanin and flavonol composition were observed, as described by principal component analysis. Only B-type proanthocyanidins were found in blueberry species, and highly polymerized molecules with degree of polymerization greater than 10 appeared to be the most abundant fraction. Although overall proanthocyanidin levels varied from 27.7 to 146.3 mg/100 g fruit, all species exhibited similar proanthocyanidin composition. Citric, quinic, and shikimic acid were the major identified blueberry organic acids. However, their relative abundance varied across species. In certain species either citric acid (e.g., Vaccinium darrowii) or quinic acid (e.g., Vaccinium corymbosum) was lacking.

Genotypic Variation in Anthocyanins, Phenolic Compounds, and Antioxidant Activity in Cob and Husk of Purple Field Corn

Information on phytochemicals in the cob and husk of field corn is important for the use of corn waste in the production of value-added corn products. The objectives of this study were to evaluate the variation in monomeric anthocyanin content (MAC), total phenolic content (TPC), and antioxidant activity, as determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity and Trolox equivalent antioxidant capacity (TEAC) in 53 purple field corn genotypes, and to study the correlations of these traits with color parameters. Fifty-three corn genotypes were planted in a randomized complete block design with three replications in two locations in the dry season of 2015/2016. The effects of genotype, location, and the interaction between genotype and location were significant for most characters. Genotypic variation contributed to a large portion of the total variance for all traits, accounting for 63.9–86.9%. Corn genotypes were classified into six groups based on MAC, TPC, and antioxidant activity determined by the DPPH and the TEAC methods. The highest MAC, TPC, and antioxidant activity were obtained in TB/KND//PF3 and TB/KND//PF8 for husk, and only TB/KND//PF8 for cob. They should be used as parental lines to develop corn varieties with high phytochemicals. Chroma (C*) and hue (H°) of color parameters could potentially be used as an indirect selection criterion for improving MAC, TPC, and antioxidant activity in cob. The information is useful for the improvement of phytochemicals in cob and husk of field corn.