Seed Coat Pigmentation Research Articles

Seed color patterns in domesticated common bean are regulated by MYB-bHLH-WD40 transcription factors and temperature.

Seed colors and color patterns are critical for the survival of wild plants and the consumer appeal of crops. In common bean, a major global staple, these patterns are also essential in determining market classes, yet the genetic and environmental control of many pigmentation patterns remains unresolved. In this study, we genetically mapped variation for several important seed pattern loci, including T, Bip, phbw, and Z, which co-segregated with candidate genes PvTTG1, PvMYC1, PvTT8, and PvTT2, respectively. Proteins encoded by these genes are predicted to work together in MYB-bHLH-WD40 (MBW) complexes, propagating flavonoid biosynthesis across the seed coat as observed in Arabidopsis. Whole-genome sequencing of 37 accessions identified mutations, including seven unique parallel mutations in T (PvTTG1) and non-synonymous SNPs in highly conserved residues in bipana (PvMYC1) and z (PvTT2). A 612 bp intron deletion in phbw (PvTT8) eliminated motifs conserved since the Papilionoideae origin and corresponded to a 20-fold reduction in transcript abundance. In multi-location field trials of seven varieties with partial seed coat pigmentation patterning, the pigmented seed coat area correlated positively with ambient temperature, with up to 11-fold increases in the pigmented area from the coolest to the warmest environments. In controlled growth chamber conditions, an increase of 4°C was sufficient to cause pigmentation on an average additional 21% of the seed coat area. Our results shed light on key steps of flavonoid biosynthesis in common bean. They will inform breeding efforts for seed coat color/patterning to improve consumer appeal in this nutritious staple crop.

Seed-Coat Pigmentation Plays a Crucial Role in Partner Selection and N2 Fixation in Legume-Root-Microbe Associations in African Soils.

Legume-rhizobia symbiosis is the most important plant-microbe interaction in sustainable agriculture due to its ability to provide much needed N in cropping systems. This interaction is mediated by the mutual recognition of signaling molecules from the two partners, namely legumes and rhizobia. In legumes, these molecules are in the form of flavonoids and anthocyanins, which are responsible for the pigmentation of plant organs, such as seeds, flowers, fruits, and even leaves. Seed-coat pigmentation in legumes is a dominant factor influencing gene expression relating to N2 fixation and may be responsible for the different N2-fixing abilities observed among legume genotypes under field conditions in African soils. Common bean, cowpea, Kersting's groundnut, and Bambara groundnut landraces with black seed-coat color are reported to release higher concentrations of nod-gene-inducing flavonoids and anthocyanins compared with the Red and Cream landraces. Black seed-coat pigmentation is considered a biomarker for enhanced nodulation and N2 fixation in legumes. Cowpea, Bambara groundnut, and Kersting's bean with differing seed-coat colors are known to attract different soil rhizobia based on PCR-RFLP analysis of bacterial DNA. Even when seeds of the same legume with diverse seed-coat colors were planted together in one hole, the nodulating bradyrhizobia clustered differently in the PCR-RFLP dendrogram. Kersting's groundnut, Bambara groundnut, and cowpea with differing seed-coat colors were selectively nodulated by different bradyrhizobial species. The 16S rRNA amplicon sequencing also found significant selective influences of seed-coat pigmentation on microbial community structure in the rhizosphere of five Kersting's groundnut landraces. Seed-coat color therefore plays a dominant role in the selection of the bacterial partner in the legume-rhizobia symbiosis.

The pattern of genetic variability in a core collection of 2,021 cowpea accessions.

Cowpea is a highly drought-adapted leguminous crop with great promise for improving agricultural sustainability and food security. Here, we report analyses derived from array-based genotyping of 2,021 accessions constituting a core subset of the world's largest cowpea collection, held at the International Institute of Tropical Agriculture (IITA) in Ibadan, Nigeria. We used this dataset to examine genetic variation and population structure in worldwide cowpea. We confirm that the primary pattern of population structure is two geographically defined subpopulations originating in West and East Africa, respectively, and that population structure is associated with shifts in phenotypic distribution. Furthermore, we establish the cowpea core collection as a resource for genome-wide association studies by mapping the genetic basis of several phenotypes, with a focus on seed coat pigmentation patterning and color. We anticipate that the genotyped IITA Cowpea Core Collection will serve as a powerful tool for mapping complex traits, facilitating the acceleration of breeding programs to enhance the resilience of this crop in the face of rapid global climate change.

Genetic Dissection of Diverse Seed Coat Patterns in Cowpea through a Comprehensive GWAS Approach.

This study investigates the genetic determinants of seed coat color and pattern variations in cowpea (Vigna unguiculata), employing a genome-wide association approach. Analyzing a mapping panel of 296 cowpea varieties with 110,000 single nucleotide polymorphisms (SNPs), we focused on eight unique coat patterns: (1) Red and (2) Cream seed; (3) White and (4) Brown/Tan seed coat; (5) Pink, (6) Black, (7) Browneye and (8) Red/Brown Holstein. Across six GWAS models (GLM, SRM, MLM, MLMM, FarmCPU from GAPIT3, and TASSEL5), 13 significant SNP markers were identified and led to the discovery of 23 candidate genes. Among these, four specific genes may play a direct role in determining seed coat pigment. These findings lay a foundational basis for future breeding programs aimed at creating cowpea varieties aligned with consumer preferences and market requirements.

Genetic mapping of QTLs controlling brown seed coat traits by genome resequencing in sesame (Sesamum indicum L.).

Sesame seeds have become an irreplaceable source of edible oils and food products with rich nutrients and a unique flavor, and their metabolite contents and physiological functions vary widely across different seed coat colors. Although the quantitative trait loci (QTLs) for genetic variation in seed coat color have been extensively investigated, the identification of unique genetic loci for intermediate colors such as brown has not been reported due to their complexity. Here, we crossed the white sesame 'Yuzhi No. 8' (YZ8) and the brown sesame 'Yanzhou Erhongpi' (YZEHP) to construct a recombinant inbred line (RIL) population with consecutive self-fertilization for ten generations. The selfed F1 seeds were brown which was controlled by a dominant gene. Based on the genotyping by whole-genome resequencing of the RILs, a major-effect QTL for brown coat color was identified through both bulk segregant analysis (BSA) and genetic linkage mapping in sesame, which was located within a 1.19 Mb interval on chromosome 6 (qBSCchr6). Moreover, we found that the YZEHP seed coat initially became pigmented at 20 days post-anthesis (DPA) and was substantially colored at 30 DPA. We screened 13 possible candidate genes based on the effects of genetic variants on protein coding and predicted gene functions. Furthermore, qRT‒PCR was used to verify the expression patterns of these genes in different post-anthesis developmental periods. We noted that in comparison to YZ8 seeds, YZEHP seeds had expression of SIN_1023239 that was significantly up-regulated 2.5-, 9.41-, 6.0-, and 5.9-fold at 15, 20, 25, and 30 DPA, respectively, which was consistent with the pattern of brown seed coat pigment accumulation. This study identified the first major-effect QTL for the control of the brown seed coat trait in sesame. This finding lays the foundation for further fine mapping and cloning as well as investigating the regulatory mechanism of seed coat color in sesame.

Pumpkin seed coat pigments affected aqueous enzymatic extraction processing through interaction with its interfacial protein

In this study, the oil recovery from pumpkin seed with or without the presence of pigment was evaluated during the aqueous enzymatic extraction process (AEEP). Additionally, the interaction of pumpkin seed coat pigment—protochlorophyll (Pchl) with interfacial proteins (globulin-O/W, globulin-W, and albumin-W) during the aqueous extraction process was investigated. When Pchl was removed from pumpkin seeds, the yield of free oil was significantly increased by 50.71% after the first centrifugation. And the total oil recovery increased from 68.59% to 89.91% using enzymatic demulsification. The β-sheet percentage of globulin-O/W decreased by 5.6% with the presence of Pchl based on the circular dichroism spectra analysis. The particle size of globulin-W and albumin-W significantly increased in contrast to globulin-O/W. In addition, the increase of surface hydrophobicity and surface sulfhydryl group showed a conformational change of three protein extracts. Fluorescence spectra analyses showed that Pchl quenched the intrinsic fluorescence of globulin-W, albumin-W, and globulin-O/W in a static mode. Thermodynamic analyses indicated that the main force between Pchl and proteins was hydrophobic interactions. The hydrolysis efficiency of Papain was reduced during demulsification in AEEP with the presence of Pchl. Therefore, the removal of pumpkin seed coat pigments facilitated the aqueous extraction of seed oil by getting rid of the interaction of Pchl with its interfacial protein.

Metabolomics combined with transcriptomics analyses of mechanism regulating testa pigmentation in peanut.

Peanut testa (seed coat) contains large amounts of flavonoids that significantly influence seed color, taste, and nutritional qualities. There are various colors of peanut testa, however, their precise flavonoid components and regulatory mechanism of pigmentation remain unclear. In this study, a total of 133 flavonoids were identified and absolutely quantified in the seed coat of four peanut cultivars with different testa color using a widely targeted metabolomic approach. Black peanut skin had more types and substantial higher levels of cyanidin-based anthocyanins, which possibly contribute to its testa coloration. Procyanidins and flavan-3-ols were the major co-pigmented flavonoids in the red, spot and black peanuts, while flavanols were the most abundant constitutes in white cultivar. Although the concentrations as well as composition characteristics varied, the content ratios of procyanidins to flavan-3-ols were similar in all samples except for white peanut. Furthermore, MYB-like transcription factors, anthocyanidin reductases (ANR), and UDP-glycosyltransferases (UGT) were found to be candidate genes involved in testa pigmentation via RNA-seq and weighted gene co-expression network analysis. It is proposed that UGTs and ANR compete for the substrate cyanidin and the prevalence of UGTs activities over ANR one will determine the color pattern of peanut testa. Our results provide a comprehensive report examining the absolute abundance of flavonoid profiles in peanut seed coat, and the finding are expected to be useful for further understanding of regulation mechanisms of seed coat pigmentation in peanut and other crops.

BnbHLH92a negatively regulates anthocyanin and proanthocyanidin biosynthesis in Brassica napus

Yellow seed trait is a desirable characteristic with potential for increasing seed quality and commercial value in rapeseed, and anthocyanin and proanthocyanidins (PAs) are major seed-coat pigments. Few transcription factors involved in the regulation of anthocyanin and PAs biosynthesis have been characterized in rapeseed. In this study, we identified a transcription factor gene BnbHLH92a (BnaA06T0441000ZS) in rapeseed. Overexpressing BnbHLH92a both in Arabidopsis and in rapeseed reduced levels of anthocyanin and PAs. Correspondingly, the expression profiles of anthocyanin and PA biosynthesis genes (TT3, BAN, TT8, TT18, and TTG1) were shown by quantitative real-time PCR to be inhibited in BnbHLH92a-overexpressing Arabidopsis seeds, indicating that BnbHLH92a represses the anthocyanin and PA biosynthesis pathway in Arabidopsis. BnbHLH92a physically interacts with the BnTTG1 protein and represses the biosynthesis of anthocyanins and PAs in rapeseed. BnbHLH92a also binds directly to the BnTT18 promoter and represses its expression. These results suggest that BnbHLH92a is a novel upstream regulator of flavonoid biosynthesis in B. napus.

The Analysis of Partial Sequences of the Flavonone 3 Hydroxylase Gene in Lupinus mutabilis Reveals Differential Expression of Two Paralogues Potentially Related to Seed Coat Colour

Flavonone 3 hydroxylases (EC 1.14.11.9) are key enzymes in the synthesis of anthocyanins and other flavonoids. Such compounds are involved in seed coat colour and stem pigmentation. Lupinus mutabilis (tarwi) is a legume crop domesticated in the Andean region, valued for the high protein and oil content of its seeds. Tarwi accessions are being selected for cultivation in Europe under defined breeding criteria. Seed coat colour patterns are relevant breeding traits in tarwi, and these are conditioned by anthocyanin content. We identified and isolated part of the tarwi flavonone 3-hydroxylase gene (LmF3h) from two accessions with distinct seed coat colour patterns. Two partial LmF3h paralogues, with predicted 20% amino-acid changes but little predicted tertiary structure alterations, were identified in the coloured seed genotype, while only one was present in the white seed genotype. Upon selection and validation of appropriate reference genes, a RT-qPCR analysis showed that these paralogues have different levels of expression during seed development in both genotypes, although they follow the same expression patterns. DNA and transcription analyses enabled to highlight potential F3H paralogues relatable to seed coat pigmentation in tarwi and, upon biochemical and genetic confirmation, prompt marker-assisted breeding for relevant phenotypic traits associated with flavonoid synthesis.

Transcriptome Analysis of MYB Genes and Patterns of Anthocyanin Accumulation During Seed Development in Wheat.

Plants accumulate key metabolites as a response of biotic/abiotic stress conditions. In seed coats, anthocyanins, carotenoids, and chlorophylls can be found. They have been associated as important antioxidants that affect germination. In wheat, anthocyanins can impart the seed coat color which have been recognized as health-promoting nutrients. Transcription factors act as master regulators of cellular processes. Transcription complexes such as MYB-bHLH-WD40 (MBW) regulate the expression of multiple target genes in various plant species. In this study, the spatiotemporal accumulation of seed coat pigments in different developmental stages (10, 20, 30, and 40 days after pollination) was analyzed using cryo-cuts. Moreover, the accumulation of phenolic, anthocyanin, and chlorophyll contents was quantified, and the expression of flavonoid biosynthetic genes was evaluated. Finally, transcriptome analysis was performed to analyze putative MYB genes related to seed coat color, followed by further characterization of putative genes. TaTCL2, an MYB gene, was cloned and sequenced. It was determined that TaTCL2 contains a SANT domain, which is often present in proteins participating in the response to anthocyanin accumulation. Moreover, TaTCL2 transcript levels were shown to be influenced by anthocyanin accumulation during grain development. Interaction network analysis showed interactions with GL2 (HD-ZIP IV), EGL3 (bHLH), and TTG1 (WD40). The findings of this study elucidate the mechanisms underlying color formation in Triticum aestivum L. seed coats.

Pumpkin seed coat pigments affected aqueous enzymatic extraction processing through interaction with its interfacial protein

Pumpkin seed coat pigments affected aqueous enzymatic extraction processing through interaction with its interfacial protein

Two types of cinnamoyl-CoA reductase function divergently in accumulation of lignins, flavonoids and glucosinolates and enhance lodging resistance in Brassica napus

Brassica crops, which are of worldwide importance, provide various oil, vegetable and ornamental products, as well as feedstocks for animal husbandry and biofuel industry. Cinnamoyl-CoA reductase (CCR) is the entry point to the lignin pathway and a crucial locus in manipulation of associated traits, but CCR-associated metabolism and traits in Brassica crops have remained largely unstudied except in Arabidopsis thaliana. We report the identification of 16 CCR genes from Brassica napus and its parental species B. rapa and B. oleracea. The BnCCR1 and BnCCR2 subfamilies displayed divergent organ-specificity and participation in the yellow-seed trait. Their functions were dissected via overexpression of representative paralogs in B. napus. BnCCR1 was expressed preferentially in G- and H-lignin biosynthesis and vascular development, while BnCCR2 was expressed in S-lignin biosynthesis and interfascicular fiber development. BnCCR1 showed stronger effects on lignification-related development, lodging resistance, phenylpropanoid flux control, and seed coat pigmentation, whereas BnCCR2 showed a stronger effect on sinapate biosynthesis. BnCCR1 upregulation delayed bolting and flowering time, while BnCCR2 upregulation weakened the leaf vascular system in consequence of suppressed G-lignin accumulation. BnCCR1 and BnCCR2 were closely but almost oppositely linked with glucosinolate metabolism via inter-pathway crosstalk. We conclude that BnCCR1 and BnCCR2 subfamilies offer great but differing potential for manipulating traits associated with phenylpropanoids and glucosinolates. This study reveals the CCR1–CCR2 divergence in Brassicaceae and offers a resource for rapeseed breeding for lodging resistance, yellow-seed traits, and glucosinolate traits.

Black Seedcoat Pigmentation Is a Marker for Enhanced Nodulation and N2 Fixation in Bambara Groundnut (Vigna Subterranea L. Verdc.) Landraces

Field studies on the effect of differing seedcoat colour on plant growth and symbiotic performance of three Bambara groundnut landraces using the 15N natural abundance technique and ureide analysis in the xylem stream and petiole extracts revealed a consistent pattern in nodule function between ureide levels and shoot δ15N values, as well as between ureide levels and percent N derived from fixation at Gbalahi, Kpalisogu, and Manga. At those three sites, where shoot δ15N was low and percent N derived from fixation high, ureide concentrations in the xylem sap and petiole extracts were also high, indicating that the two techniques were comparatively quite robust in estimating N2 fixation at a higher precision in the test Bambara groundnut landraces. A comparison of the effect of differing seedcoat pigmentation on the concentration of phenolics released by imbibed seeds showed that the Black landrace contained higher levels of flavonoids and anthocyanins, followed by the Red, and lowest in the Cream landrace. The Black landrace also recorded much higher nodule number and nodule fresh weight per plant, greater shoot biomass, lower shoot δ15N values, greater N derived from fixation, higher symbiotic N contribution, and increased water-use efficiency across all the five study sites, followed by the Red landrace, which produced the highest grain yield. Black seedcoat pigmentation in Bambara groundnut is therefore a marker for increased nodulation, N2 fixation, and plant growth that can be tapped in breeding programs for developing high N2-fixing, water-use efficient grain legumes for use by farmers in Africa.

MYB transcription factors GmMYBA2 and GmMYBR function in a feedback loop to control pigmentation of seed coat in soybean.

Soybean has undergone extensive selection pressures for seed nutrient composition and seed color during domestication, but the major genetic loci controlling seed coat color have not been completely understood, and the transcriptional regulation relationship among the loci remains elusive. Here, two major regulators, GmMYBA2 and GmMYBR, were functionally characterized as an anthocyanin activator and repressor, respectively. Ectopic expression of GmMYBA2 in soybean hairy roots conferred the enhanced accumulation of delphinidin and cyanidin types of anthocyanins in W1t and w1T backgrounds, respectively, through activating anthocyanin biosynthetic genes in the reported loci. The seed coat pigmentation of GmMYBA2-overexpressing transgenic plants in the W1 background mimicked the imperfect black phenotype (W1/w1, i, R, t), suggesting that GmMYBA2 was responsible for the R locus. Molecular and biochemical analysis showed that GmMYBA2 interacted with GmTT8a to directly activate anthocyanin biosynthetic genes. GmMYBA2 and GmMYBR might form a feedback loop to fine-tune seed coat coloration, which was confirmed in transgenic soybeans. Both GmTT8a and GmMYBR that were activated by GmMYBA2 in turn enhanced and obstructed the formation of the GmMYBA2-GmTT8a module, respectively. The results revealed the sophisticated regulatory network underlying the soybean seed coat pigmentation loci and shed light on the understanding of the seed coat coloration and other seed inclusions.

A feature collection of lentil (Lens culinaris Medik.) by nutritious value of seeds

The study purpose was to summarize and analyze multi-year data on the nutritional quality of lentil (Lens culinaris Medik.) accessions from the basic collection of the National Center for Plant Genetic Resources of Ukraine (NCPGRU).Materials and methods. In 1992–2018, 555 accessions of the NCPGRU’s basic collection of lentils were studied. Lens culinaris Medik. accessions were represented by two subspecies: subsp. microsperma and subsp. macrosperma.The collection accessions of lentils were investigated and morphologically described; they were grouped by economic and biological features according to the Classifier of the genus Lens L.The protein content in seeds was determined by the Kjeldahl digestion in the Laboratory of Genetics, Biotechnology and Quality of the Plant Production Institute nd. a. VYa Yuriev NAAS.Results and discussion. The nutritional parameters of lentil seeds were evaluated in the full ripeness phase: protein content, cooking time, palatability, colors of cotyledons and seed coat, resistance to infuscation, and seed size.As to the protein content in seeds, the collection includes the following accessions: with a very high protein content (>30%) – one reference accession UD0600398 (Ukraine) with the protein content of 30.34%; with high protein content (29-30%) – 26 accessions; with medium protein content (26–28%) – 55 accessions; with low protein content (20–25%) – 79 accessions. As to the cooking boiling rate, the collection includes 154 accessions: with a very good rate (< 40 minutes) – 45 accessions; with a good rate (40–60 minutes) – 89 accessions; with a medium rate (61–80 minutes) – 20 accessions. Reference accessions for various levels of lentil palatability were distinguished and included in the collection: very low palatability (3 points) – LUG 330/04 (Ukraine); low palatability (5 points) – 1743 T 19 (Canada); high palatability (7 points) – Miledi, (Russia).The seed appearance is an important aspect of the market value of food lentils: the seed coat color, cotyledon color, resistance to infuscation. The accessions were grouped by cotyledon color as follows: yellow – 87 accessions; hot-yellow – 67 accessions; green – 6 accessions. In accordance with the Classifier of the genus Lens, there are currently eight types of the seed coat pigmentation; their references are listed below: white – LUG 45/09 (Ukraine); pink – LUG 116/09 (Ukraine); green – Zelenyy Chervonets (Ukraine); yellow-green – Krasnohradska 250 (Ukraine); gray – 1743 T 19 (Canada); gray-red – Elista (Slovakia); brown – UD0600444 (Ethiopia); and black – Beluga (Israel).Given the ability of the seed coat to infuscate, the reference accessions for this trait were chosen: infuscating – Krasnohradska 250 (Ukraine); non-infuscating – LUG 45/09 (Ukraine).

Arabidopsis ECHIDNA protein is involved in seed coloration, protein trafficking to vacuoles, and vacuolar biogenesis.

Flavonoids are a major group of plant-specific metabolites that determine flower and seed coloration. In plant cells, flavonoids are synthesized at the cytosolic surface of the endoplasmic reticulum and are sequestered in the vacuole. It is possible that membrane trafficking, including vesicle trafficking and organelle dynamics, contributes to flavonoid transport and accumulation. However, the underlying mechanism has yet to be fully elucidated. Here we show that the Arabidopsis ECHIDNA protein plays a role in flavonoid accumulation in the vacuole and protein trafficking to the vacuole. We found defective pigmentation patterns in echidna seed, possibly caused by reduced levels of proanthocyanidins, which determine seed coloration. The echidna mutant has defects in protein sorting to the protein storage vacuole as well as vacuole morphology. These findings indicate that ECHIDNA is involved in the vacuolar trafficking pathway as well as the previously described secretory pathway. In addition, we found a genetic interaction between echidna and green fluorescent seed 9 (gfs9), a membrane trafficking factor involved in flavonoid accumulation. Our findings suggest that vacuolar trafficking and/or vacuolar development, both of which are collectively regulated by ECHIDNA and GFS9, are required for flavonoid accumulation, resulting in seed coat pigmentation.

A major gene for tolerance to cold-induced seed coat discoloration relieves viral seed mottling in soybean.

In yellow soybeans, inhibition of seed coat pigmentation by RNA silencing of CHS genes is suppressed by low temperature and a viral suppressor, resulting in ‘cold-induced seed coat discoloration’ and ‘seed mottling’, respectively. Differences exist in the degree of cold-induced seed coat discoloration among Japanese yellow soybean cultivars; for example, Toyomusume is sensitive, Toyohomare has some tolerance, and Toyoharuka is highly tolerant. In this study, we compared the degree of seed mottling severity due to soybean mosaic virus (SMV) among these three soybean cultivars. Obvious differences were found, with the order of severity as follows: Toyohomare > Toyomusume > Toyoharuka. RNA gel blot analysis indicated that CHS transcript abundance in the seed coat, which was increased by SMV infection, was responsible for the severity of seed mottling. Quantitative reverse transcription PCR analysis revealed why mottling was most severe in SMV-infected Toyohomare: the SMV titer in its seed coat was higher than in the other two infected cultivars. We further suggest that a major gene (Ic) for tolerance to cold-induced seed coat discoloration can relieve the severity of seed mottling in SMV-infected Toyoharuka.

Diversity of genetic lesions characterizes new Arabidopsis flavonoid pigment mutant alleles from T-DNA collections

The visual phenotypes afforded by flavonoid pigments have provided invaluable tools for modern genetics. Many Arabidopsis transparent testa (tt) mutants lacking the characteristic proanthocyanidin (PA) seed coat pigmentation and often failing to accumulate anthocyanins in vegetative tissues have been characterized. These mutants have significantly contributed to our understanding of flavonoid biosynthesis, regulation, and transport. A comprehensive screening for tt mutants in available large T-DNA collection lines resulted in the identification of 16 independent lines lacking PAs and anthocyanins, or with seed coat pigmentation clearly distinct from wild type. Segregation analyses and the characterization of second alleles in the genes disrupted by the indexed T-DNA insertions demonstrated that all the lines contained at least one additional mutation responsible for the tt phenotypes. Using a combination of RNA-Seq and whole genome re-sequencing and confirmed through complementation, we show here that these mutations correspond to novel alleles of ttg1 (two alleles), tt3 (two alleles), tt5 (two alleles), ban (two alleles), tt1 (two alleles), and tt8 (six alleles), which harbored additional T-DNA insertions, indels, missense mutations, and large genomic deletion. Several of the identified alleles offer interesting perspectives on flavonoid biosynthesis and regulation.

Identification and quantification of anthocyanins in seeds of Kersting’s groundnut [Macrotyloma geocarpum (Harms) Marechal & Baudet] landraces of varying seed coat pigmentation

The present study identified and quantified the anthocyanin pigments in seed of eight Kersting’s groundnut [Macrotyloma geocarpum (Harms) Marechal & Baudet] landraces of variable seed coat pigmentation. The analysis was carried out using ultra-performance liquid chromatography coupled with a photodiode array detector and mass spectrometry. Although the findings revealed similar anthocyanin profiles in seeds of the eight landraces tested, the relative concentrations of the individual anthocyanin compounds showed marked variations. Delphinidin-3-O-glucoside, cyanidin-3-O-glucoside and peonidin-3-O-glucoside were the most abundant anthocyanins, with concentrations ranging between 21.4–239.0, 23.6–130.6 and 21.4–135.4 µg/g of dry seed, respectively in seeds of the test landraces, while total anthocyanins ranged between 95 and 505 µg/g of dry seed. The preponderance of delphinidin 3-O-glucoside was observed in the black and brown mottled seeds. This study is the first report regarding the profile and concentrations of anthocyanins in Kersting’s groundnut and suggests that the seeds of this underutilized grain legume can potentially be exploited as a natural source of anthocyanins for the development of cosmetic, food and pharmaceutical products.

Structure of two purple pigments, catechinopyranocyanidins A and B from the seed-coat of the small red bean, Vigna angularis

The small red bean, Vigna angularis, is primarily used to produce the “an-paste” component of Japanese sweets. Through the manufacturing process, the red seed-coat pigment is transferred to the colorless “an-particles”, imparting a purple color. However, the major pigment in the seed coat has not yet been identified, although it is historically presumed to be an anthocyanin. Here, we report the isolation and structural determination of two hydrophobic purple pigments in the seed coat via instrumental analysis and derivatization. The new pigments, catechinopyranocyanidins A and B, contain a novel pyranoanthocyanidin skeleton condensed with a catechin and cyanidin ring system, and no sugar moieties. Catechinopyranocyanidins A and B are diastereomers with a different configuration at the catechin moiety, and both are purple in color in strongly acidic-to-neutral media. Catechinopyranocyanidins A and B are very stable under dark conditions, but, labile to light and decompose to colorless compounds. Thus, these pigments exhibit quite different chemical properties compared to simple anthocyanidins.