Time maters: Exploring the dynamics of bioactive compounds content, bioaccessibility and antioxidant activity during Lupinus angustifolius germination.

Germination is a process that enhances the content of health-promoting secondary metabolites. However, the bioaccessibility of these compounds depends on their stability and solubility throughout the gastrointestinal tract. The study aimed to explore how germination time influences the content and bioaccessibility of γ-aminobutyric acid and polyphenols and antioxidant capacity of lupin (Lupinus angustifolius L.) sprouts during simulated gastrointestinal digestion. Gamma-aminobutyric acid showed a decrease following gastrointestinal digestion (GID) whereas phenolic acids and flavonoids exhibited bioaccessibilities of up to 82.56 and 114.20%, respectively. Although the digestion process affected the profile of phenolic acids and flavonoids, certain isoflavonoids identified in 7-day sprouts (G7) showed resistance to GID. Germination not only favored antioxidant activity but also resulted in germinated samples exhibiting greater antioxidant properties than ungerminated counter parts after GID. Intestinal digests from G7 did not show cytotoxicity in RAW 264.7 macrophages, and notably, they showed an outstanding ability to inhibit the production of reactive oxygen species. This suggests potential benefit in mitigating oxidative stress. These findings contribute to understand the dynamic interplay between bioprocessing and digestion in modulating the bioaccessibility of bioactive compounds in lupin, thereby impacting health.

Lupin as a Source of Bioactive Antioxidant Compounds for Food Products.

Four species of lupin (white lupin, yellow lupin, blue lupin and Andean lupin) are widely cropped thanks to the excellent nutritional composition of their seeds: high protein content (28-48 g/100 g); good lipid content (4.6-13.5 g/100 g, but up to 20.0 g/100 g in Andean lupin), especially unsaturated triacylglycerols; and richness in antioxidant compounds like carotenoids, tocols and phenolics. Particularly relevant is the amount of free phenolics, highly bioaccessible in the small intestine. However, the typical bitter and toxic alkaloids must be eliminated before lupin consumption, hindering its diffusion and affecting its nutritional value. This review summarises the results of recent research in lupin composition for the above-mentioned three classes of antioxidant compounds, both in non-debittered and debittered seeds. Additionally, the influence of technological processes to further increase their nutritional value as well as the effects of food manufacturing on antioxidant content were scrutinised. Lupin has been demonstrated to be an outstanding raw material source, superior to most crops and suitable for manufacturing foods with good antioxidant and nutritional properties. The bioaccessibility of lupin antioxidants after digestion of ready-to-eat products still emerges as a dearth in current research.

Functional Association between Storage Protein Mobilization and Redox Signaling in Narrow-Leafed Lupin (Lupinus angustifolius L.) Seed Germination and Seedling Development.

(1) Background: Seed storage mobilization, together with oxidative metabolism, with the ascorbate-glutathione (AsA-GSH) cycle as a crucial signaling and metabolic functional crossroad, is one of the main regulators of the control of cell morphogenesis and division, a fundamental physiological process driving seed germination and seedling growth. This study aims to characterize the cellular changes, composition, and patterns of the protein mobilization and ROS-dependent gene expression of redox metabolism in Lupinus angustifolius L. (narrow-leafed lupin, NLL) cotyledons during seed germination. (2) Methods: We performed gene expression analyses via RT-qPCR for conglutins α (1, 2, and 3), ß (1, 2, and 5), γ (1, 2), and δ (2 and 4), including a ubiquitin gene as a control, and for redox metabolism-related genes; GADPH was used as a control gene. A microscopic study was developed on cotyledon samples from different germination stages, including as IMB (imbibition), and 2-5, 7, 9, and 11 DAI (days after imbibition), which were processed for light microscopy. SDS-PAGE and immunocytochemistry assays were performed using an anti-ß-conglutin antibody (Agrisera), and an anti-rabbit IgG Daylight 488-conjugated secondary antibody. The controls were made while omitting primary Ab. (3) Results and Discussion: Our results showed that a large amount of seed storage protein (SSP) accumulates in protein bodies (PBs) and mobilizes during germination. Families of conglutins (ß and γ) may play important roles as functional and signaling molecules, beyond the storage function, at intermediate steps of the seed germination process. In this regard, metabolic activities are closely associated with the regulation of oxidative homeostasis through AsA-GSH activities (γ-L-Glutamyl-L-cysteine synthetase, NOS, Catalase, Cu/Zn-SOD, GPx, GR, GS, GsT) after the imbibition of NLL mature seeds, metabolism activation, and dormancy breakage, which are key molecular and regulatory signaling pathways with particular importance in morphogenesis and developmental processes. (4) Conclusions: The knowledge generated in this study provides evidence for the functional changes and cellular tightly regulated events occurring in the NLL seed cotyledon, orchestrated by the oxidative-related metabolic machinery involved in seed germination advancement.

Abscisic acid- and ethylene-induced abscission of yellow lupine flowers is mediated by jasmonates.

The appropriate timing of organ abscission determines plant growth, development, reproductive success, and yield in relation to crop species. Among these, yellow lupine is an example of a crop species that loses many fully developed flowers, which limits the formation of pods with high-protein seeds and affects its economic value. Lupine flower abscission, similarly to the separation of other organs, depends on a complex regulatory network functioning in the cells of the abscission zone (AZ). In the present study, genetic, biochemical, and cellular methods were used to highlight the complexity of the interactions among strong hormonal stimulators of abscission, including abscisic acid (ABA), ethylene, and jasmonates (JAs) precisely in the AZ cells, with all results supporting that the JA-related pathway has an important role in the phytohormonal cross-talk leading to flower abscission in yellow lupine. Based on obtained results, we conclude that ABA and ET have positive influence on JAs biosynthesis and signaling pathway in time-dependent manner. Both phytohormones changes lipoxygenase (LOX) gene expression, affects LOX protein abundance, and JA accumulation in AZ cells. We have also shown that the signaling pathway of JA is highly sensitive to ABA and ET, given the accumulation of COI1 receptor and MYC2 transcription factor in response to these phytohormones. The results presented provide novel information about the JAs-dependent separation of organs and provide insight and details about the phytohormone-related mechanisms of lupine flower abscission.

A not-glycosylated isoform of γ-conglutin, a hexameric glycoprotein of Lupinus albus seed, participates in the oligomerization equilibrium.

γ-conglutin (γ-C) is a hexameric glycoprotein accumulated in lupin seeds and has long been considered as a storage protein. Recently, it has been investigated for its possible postprandial glycaemic regulating action in human nutrition and for its physiological role in plant defence. The quaternary structure of γ-C results from the assembly of six monomers in reversible pH-dependent association/dissociation equilibrium. Our working hypothesis was that the γ-C hexamer is made up of glycosylated subunits in association with not-glycosylated isoforms, that seem to have 'escaped' the correct glycosylation process in the Golgi. Here we describe the isolation of not-glycosylated γ-C monomers in native condition by two in tandem lectin-based affinity chromatography and the characterization of their oligomerization capacity. We report, for the first time, the observation that a plant multimeric protein may be formed by identical polypeptide chains that have undergone different post-translational modifications. All obtained considered, the results strongly suggest that the not-glycosylated isoform can also take part in the oligomerization equilibrium of the protein.

GPETAFLR, a peptide from Lupinus angustifolius L. prevents inflammation in microglial cells and confers neuroprotection in brain.

OBJECTIVES: Neuroinflammation is a complex inflammatory process in the central nervous system (CNS) where microglia may play a critical role. GPETAFLR is a peptide isolated from Lupinus angustifolius L. protein hydrolysates with functional activity in mononuclear phagocytes. However, it is unknown whether GPETAFLR has neuroprotective effects. METHODS: We analysed the potential anti-neuroinflammatory activity of GPETAFLR by using two different models of neuroinflammation: BV-2 microglial cells and mice with high-fat diet (HFD)-induced obesity. RESULTS: GPETAFLR hampered LPS-induced upregulation of pro-inflammatory and M1 marker genes in BV-2 cells. This effect was accompanied by an unchanged expression of anti-inflammatory IL-10 gene and by an increased expression of M2 marker genes. GPETAFLR also increased the transcriptional activity of M2 marker genes, while the microglia population remained unchanged in number and M1/M2 status in brain of mice with high-fat diet (HFD)-induced obesity. Furthermore, GPETAFLR counteracted HFD-induced downregulation of IL-10 and upregulation of pro-inflammatory markers in the mouse brain, both at gene and protein levels. DISCUSSION: This is the first report describing that a peptide from plant origin robustly restrained the pro-inflammatory activation of microglial cells in cultures and in brain. Our data suggest that GPETAFLR might be instrumental in maintaining CNS homeostasis by inhibiting neuroinflammation.

Identification and characterization of unique 5-hydroxyisoflavonoid biosynthetic key enzyme genes in Lupinus albus.

KEY MESSAGE: 5-Hydroxyisoflavonoids, no 5-deoxyisoflavonoids, in Lupinus species, are due to lack of CHRs and Type II CHIs, and the key enzymes of isoflavonoid biosynthetic pathway in white lupin were identified. White lupin (Lupinus albus) is used as food ingredients owing to rich protein, low starch, and rich bioactive compounds such as isoflavonoids. The isoflavonoids biosynthetic pathway in white lupin still remains unclear. In this study, only 5-hydroxyisoflavonoids, but no 5-deoxyisoflavonoids, were detected in white lupin and other Lupinus species. No 5-deoxyisoflavonoids in Lupinus species are due to lack of CHRs and Type II CHIs. We further found that the CHI gene cluster containing both Type I and Type II CHIs possibly arose after the divergence of Lupinus with other legume clade. LaCHI1 and LaCHI2 identified from white lupin metabolized naringenin chalcone to naringenin in yeast and tobacco (Nicotiana benthamiana), and were bona fide Type I CHIs. We further identified two isoflavone synthases (LaIFS1 and LaIFS2), catalyzing flavanone naringenin into isoflavone genistein and also catalyzing liquiritigenin into daidzein in yeast and tobacco. In addition, LaG6DT1 and LaG6DT2 prenylated genistein at the C-6 position into wighteone. Two glucosyltransferases LaUGT1 and LaUGT2 metabolized genistein and wighteone into its 7-O-glucosides. Taken together, our study not only revealed that exclusive 5-hydroxyisoflavonoids do exist in Lupinus species, but also identified key enzymes in the isoflavonoid biosynthetic pathway in white lupin.

Lupinus albus Protein Components Inhibit MMP-2 and MMP-9 Gelatinolytic Activity In Vitro and In Vivo.

Matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9) are regarded as important clinical targets due to their nodal-point role in inflammatory and oncological diseases. Here, we aimed at isolating and characterizing am MMP-2 and-9 inhibitor (MMPI) from Lupinus albus and at assessing its efficacy in vitro and in vivo. The protein was isolated using chromatographic and 2-D electrophoretic procedures and sequenced by using MALDI-TOF TOF and MS/MS analysis. In vitro MMP-2 and 9 inhibitions were determined on colon adenocarcinoma (HT29) cells, as well as by measuring the expression levels of genes related to these enzymes. Inhibitory activities were also confirmed in vivo using a model of experimental TNBS-induced colitis in mice, with oral administrations of 15 mg·kg-1. After chromatographic and electrophoretic isolation, the L. albus MMP-9 inhibitor was found to comprise a large fragment from δ-conglutin and, to a lower extent, small fragments of ß-conglutin. In vitro studies showed that the MMPI successfully inhibited MMP-9 activity in a dose-dependent manner in colon cancer cells, with an IC50 of 10 µg·mL-1 without impairing gene expression nor cell growth. In vivo studies showed that the MMPI maintained its bioactivities when administered orally and significantly reduced colitis symptoms, along with a very significant inhibition of MMP-2 and -9 activities. Overall, results reveal a novel type of MMPI in lupine that is edible, proteinaceous in nature and soluble in water, and effective in vivo, suggesting a high potential application as a nutraceutical or a functional food in pathologies related to abnormally high MMP-9 activity in the digestive system.

Untargeted Phytochemical Profile, Antioxidant Capacity and Enzyme Inhibitory Activity of Cultivated and Wild Lupin Seeds from Tunisia.

Lupin seeds can represent a valuable source of phenolics and other antioxidant compounds. In this work, a comprehensive analysis of the phytochemical profile was performed on seeds from three Lupinus species, including one cultivar (Lupinus albus) and two wild accessions (Lupinus cossentinii and Lupinus luteus), collected from the northern region of Tunisia. Untargeted metabolomic profiling allowed to identify 249 compounds, with a great abundance of phenolics and alkaloids. In this regard, the species L. cossentinii showed the highest phenolic content, being 6.54 mg/g DW, followed by L. luteus (1.60 mg/g DW) and L. albus (1.14 mg/g DW). The in vitro antioxidant capacity measured by the ABTS assay on seed extracts ranged from 4.67 to 17.58 mg trolox equivalents (TE)/g, recording the highest values for L. albus and the lowest for L. luteus. The DPPH radical scavenging activity ranged from 0.39 to 3.50 mg TE/g. FRAP values varied between 4.11 and 5.75 mg TE/g. CUPRAC values for lupin seeds ranged from 7.20 to 8.95 mg TE/g, recording the highest for L. cossentinii. The results of phosphomolybdenum assay and metal chelation showed similarity between the three species of Lupinus. The acetylcholinesterase (AChE) inhibition activity was detected in each methanolic extract analyzed with similar results. Regarding the butyrylcholinesterase (BChE) enzyme, it was weakly inhibited by the Lupinus extracts; in particular, the highest activity values were recorded for L. albus (1.74 mg GALAE/g). Overall, our results showed that L. cossentinii was the most abundant source of polyphenols, consisting mainly in tyrosol equivalents (5.82 mg/g DW). Finally, significant correlations were outlined between the phenolic compounds and the in vitro biological activity measured, particularly when considering flavones, phenolic acids and lower-molecular-weight phenolics.

Identification of dipeptidyl peptidase IV (DPP-IV) inhibitory peptides from vegetable protein sources.

Vegetable proteins are appearing as a sustainable source for human consumption. Food-derived peptides are an important field of research in terms of bioactive molecules. In this study, seven vegetable proteins were enzymatically hydrolysed following an optimised treatment (sequential hydrolysis with subtilisin-trypsin-flavourzyme) to obtain dipeptidyl peptidase IV (DPP-IV) inhibitory peptides. Hydrolysates were fractionated by size exclusion chromatography and, from the most bioactive fractions (corresponding to Glycine max, Chenopodium quinoa and Lupinus albus proteins); peptides responsible for this bioactivity were identified by mass spectrometry. Peptides with adequate molecular features and based on in silico analysis were proposed as DPP-IV inhibitors from soy (EPAAV) lupine (NPLL), and quinoa (APFTVV). These vegetable protein sources are adequate to obtain protein hydrolysates for functional food.

Physiological and transcriptomic data highlight common features between iron and phosphorus acquisition mechanisms in white lupin roots.

In agricultural soil, the bioavailability of iron (Fe) and phosphorus (P) is often below the plant's requirement causing nutritional deficiency in crops. Under P-limiting conditions, white lupin (Lupinus albus L.) activates mechanisms that promote P solubility in the soil through morphological, physiological and molecular adaptations. Similar changes occur also in Fe-deficient white lupin roots; however, no information is available on the molecular bases of the response. In the present work, responses to Fe and P deficiency and their reciprocal interactions were studied. Transcriptomic analyses indicated that white lupin roots upregulated Fe-responsive genes ascribable to Strategy-I response, this behaviour was mainly evident in cluster roots. The upregulation of some components of Fe-acquisition mechanism occurred also in P-deficient cluster roots. Concerning P acquisition, some P-responsive genes (as phosphate transporters and transcription factors) were upregulated by P deficiency as well by Fe deficiency. These data indicate a strong cross-connection between the responses activated under Fe or P deficiency in white lupin. The activation of Fe- and P-acquisition mechanisms might play a crucial role to enhance the plant's capability to mobilize both nutrients in the rhizosphere, especially P from its associated metal cations.

Invasion windows for a global legume invader are revealed after joint examination of abiotic and biotic filters.

Successful alien plant invasion is influenced by both climate change and plant-plant interactions. We estimate the single and interactive effects of competition and extreme weather events on the performance of the global legume invader Lupinus polyphyllus (Lindl.). In three experimental studies we assessed (i) the stress tolerance of seedling and adult L. polyphyllus plants against extreme weather events (drought, fluctuating precipitation, late frost), (ii) the competitive effects of L. polyphyllus on native grassland species and vice versa, and (iii) the interactive effects of extreme weather events and competition on the performance of L. polyphyllus. Drought reduced growth and led to early senescence of L. polyphyllus but did not reduce adult survival. Fluctuating precipitation events and late frost reduced the length of inflorescences. Under control conditions, interspecific competition reduced photosynthetic activity and growth of L. polyphyllus. When subjected to competition during drought, L. polyphyllus conserved water while simultaneously maintaining high assimilation rates, demonstrating increased water use efficiency. Meanwhile, native species had reduced performance under drought. In summary, the invader gained an advantage under drought conditions through a smaller reduction in performance relative to its native competitors but was competitively inferior under control conditions. This provides evidence for a possible invasion window for this species. While regions of high elevation or latitude with regular severe late frost events might remain inaccessible for L. polyphyllus, further spread across Europe seems probable as the predicted increase in drought events may favour this non-native legume over native species.

The LaCEP1 peptide modulates cluster root morphology in Lupinus albus.

White lupin cluster roots are specialized brush-like root structures that are formed in some species under phosphorus (P)-deficient conditions. They intensely secrete protons and organic acid anions for solubilization and acquisition of sparingly soluble phosphates. Phytohormones and sucrose modulate cluster root number, but the molecular mechanisms of cluster root formation have been elusive. Here, a novel peptide phytohormone was identified that affects cluster root development. It belongs to the C-TERMINALLY-ENCODED PEPTIDE (CEP) family. Members of that family arrest root growth and modulate branching in model species. LaCEP1 was highly expressed in the pre-emergence zone of clusters. Over-expression of the gene encoding the LaCEP1 propeptide resulted in moderate inhibition of cluster root formation. The primary and lateral root lengths of lupin were little affected by the overexpression, but LaCEP1 reduced cluster rootlet and root hair elongation. Addition of a 15-mer core peptide derived from LaCEP1 similarly altered root morphology and modified cluster activity, suggesting that a core sequence of the propeptide is functionally sufficient. Stable overexpression in Arabidopsis confirmed the LaCEP1 function in root growth inhibition across species. Taken together, the root inhibitory effects of the LaCEP1 phytohormone suggest a role as of a regulatory module involved in cluster root development in white lupin.

Gibberellic acid affects the functioning of the flower abscission zone in Lupinus luteus via cooperation with the ethylene precursor independently of abscisic acid.

The abscission of plant organs is a phytohormone-controlled process. Our study provides new insight into the involvement of gibberellic acid (GA3) in the functioning of the flower abscission zone (AZ) in yellow lupine (Lupinus luteus L.). Physiological studies demonstrated that GA3 stimulated flower abortion. Additionally, this phytohormone was abundantly presented in the AZ cells of naturally abscised flowers, especially in vascular bundles. Interesting interactions among GA3 and other modulators of flower separation were also investigated. GA3 accumulated after treatment with the ethylene (ET) precursor 1-aminocyclopropane-1-carboxylic acid (ACC). Abscisic acid (ABA) treatment did not cause such an effect. Furthermore, the expression of the newly identified LlGA20ox1 and LlGA2ox1 genes encoding 2-oxoglutarate-dependent dioxygenases fluctuated after ACC or ABA treatment which confirmed the existence of regulatory crosstalk. GA3 appears to cooperate with the ET precursor in the regulation of AZ function in L. luteus flowers; however, the presented mechanism is ABA-independent.

Biomolecules-mediated synthesis of selenium nanoparticles using Aspergillus oryzae fermented Lupin extract and gamma radiation for hindering the growth of some multidrug-resistant bacteria and pathogenic fungi.

Biosynthesis of nanoparticles by fermented plants using microbes is an eco-friendly and cost-effective process. In this study, we used the fungus Aspergillus orayzae for the fermentation process. The aqueous extract of fermented Lupin (AEFL) possesses the ability to reduce selenium ion in the presence of gamma rays evidenced by the color changes to red. Elemental composition, surface morphology, size determenation, and identity of selenium nanoparticles (SeNPs) were verified by UV-Vis., TEM, DLS, XRD, EDX, SEM and FT-IR. Antimicrobial activity of SeNPs was tested towards multidrug-resistant (MDR) bacteria, and some pathogenic fungi. TEM with DLS analysis confirmed the formation of sphere isotropic, poly-dispersed SeNPs with average particle size 55.0 nm. The nucleation and mechanism of SeNPs production was discussed. Our results revealed that, gamma ray (30.0 kGy) was played a significant role in SeNPs synthesis. The synthesized SeNPs were active towards Acinetobacter calcoaceticus (15.0 mm ZOI) and Staphylococcus aurus (16.6 mm ZOI). Additionally, SeNPs were inhibiting Candida albicans (15.3 mm ZOI) and mycotoxin producing Aspergillus flavus (29.6 mm ZOI). Depending on the unique characteristics, and the novelty in biosynthesis process of SeNPs, it must be candidates in biomedicine, prevent food spoilage, cosmetics, and pharmaceutics as green antimicrobial agent.

Phenolic contents and antioxidant capacities of wild and cultivated white lupin (Lupinus albus L.) seeds.

The aim of this study was to compare the antioxidant capacities and phenolic compound profiles of wild and cultivated Lupinus albus L. seeds. The total phenolic content (TPC), radical scavenging activity, ferric-reducing antioxidant power (FRAP) and antioxidant activity in an ß-carotene-linoleic acid emulsion were determined. Liquid chromatography-mass spectrometry was used to identify phenolics. The TPC of lupin seeds ranged from 4.36 to 7.24 mg gallic acid equivalent/g dry matter (d.m.). The dominant phenolics of all genotypes were two p-coumaric acid derivatives (0.74-1.61 and 0.66-1.63 mg/g d.m.) and apigenin-6,8-di-C-glucoside (1.13-1.31 mg/g d.m.). The results of antioxidant assays of wild lupin extracts were similar to or lower than those of the cultivated variety. FRAP and ABTS+ scavenging activity were correlated with the contents of the more polar p-coumaric acid derivative and apigenin-6,8-di-C-glucoside. Generally, significant differences between cultivated and wild L. albus seeds were not found in antioxidant capacities and phenolic compound contents.

Gas Chromatography/Mass Spectrometry-Based Metabolite Profiling of Nutrients and Antinutrients in Eight Lens and Lupinus Seeds (Fabaceae).

Lens culinaris and several Lupinus species are two legumes regarded as potential protein resources aside from their richness in phytochemicals. Consequently, characterization of their metabolite composition seems warranted to be considered as a sustainable commercial functional food. This study presents a discriminatory holistic approach for metabolite profiling in accessions of four lentil cultivars and four Lupinus species via gas chromatography/mass spectrometry. A total of 107 metabolites were identified, encompassing organic and amino acids, sugars, and sterols, along with antinutrients, viz., alkaloids and sugar phosphates. Among the examined specimens, four nutritionally valuable accessions ought to be prioritized for future breeding to include Lupinus hispanicus, enriched in organic ( ca. 11.7%) and amino acids ( ca. 5%), and Lupinus angustifolius, rich in sucrose ( ca. 40%), along with two dark-colored lentil cultivars 'verte du Puy' and 'Black Beluga' enriched in peptides. Antinutrient chemicals were observed in Lupinus polyphyllus, owing to its high alkaloid content. Several species-specific markers were also revealed using multivariate data analyses.

Bioactivities of alternative protein sources and their potential health benefits.

Increasing the utilisation of plant proteins is needed to support the production of protein-rich foods that could replace animal proteins in the human diet so as to reduce the strain that intensive animal husbandry poses to the environment. Lupins, quinoa and hempseed are significant sources of energy, high quality proteins, fibre, vitamins and minerals. In addition, they contain compounds such as polyphenols and bioactive peptides that can increase the nutritional value of these plants. From the nutritional standpoint, the right combination of plant proteins can supply sufficient amounts of essential amino acids for human requirements. This review aims at providing an overview of the current knowledge of the nutritional properties, beneficial and non-nutritive compounds, storage proteins, and potential health benefits of lupins, quinoa and hempseed.

Calcium, Iron, and Zinc Bioaccessibilities of Australian Sweet Lupin (Lupinus angustifolius L.) Cultivars.

In this study, we aimed to determine the effect of the cultivar and dehulling on calcium, iron, and zinc bioaccessibilities of Australian sweet lupin (ASL). Ten ASL cultivars grown in 2011, 2012, and 2013 in Western Australia were used for the study. The bioaccessibilities of calcium, iron, and zinc in whole seed and dehulled lupin samples were determined using a dialysability method. The cultivar had significant effects on calcium, iron, and zinc contents and their bioaccessibilities. Average bioaccessibilities of 6% for calcium, 17% for iron, and 9% for zinc were found for whole seeds. Dehulled ASL had average calcium, iron, and zinc bioaccessibilities of 11%, 21%, and 12%, respectively. Compared to some other pulses, ASL had better iron bioaccessibility and poorer calcium and zinc bioaccessibilities. Dehulling increased calcium bioaccessibilities of almost all lupin cultivars. The effect of dehulling on iron and zinc bioaccessibilities depends on the ASL cultivar.

Iron plaque formed under aerobic conditions efficiently immobilizes arsenic in Lupinus albus L roots.

Arsenic is a non-threshold carcinogenic metalloid. Thus, human exposure should be minimised, e.g. by chemically stabilizing As in soil. Since iron is a potential As immobiliser, it was investigated whether root iron plaque, formed under aerobic conditions, affects As uptake, metabolism and distribution in Lupinus albus plants. White lupin plants were cultivated in a continuously aerated hydroponic culture containing Fe/EDDHA or FeSO4 and exposed to arsenate (5 or 20 µM). Only FeSO4 induced surficial iron plaque in roots. LA-ICP-MS analysis accomplished on root sections corroborated the association of As to this surficial Fe. Additionally, As(V) was the predominant species in FeSO4-treated roots, suggesting less efficient As uptake in the presence of iron plaque. Fe/EDDHA-exposed roots neither showed such surficial FeAs co-localisation nor As(V) accumulation; in contrast As(III) was the predominant species in root tissue. Furthermore, FeSO4-treated plants showed reduced shoot-to-root As ratios, which were >10-fold lower compared to Fe/EDDHA treatment. Our results highlight the role of an iron plaque formed in roots of white lupin under aerobic conditions on As immobilisation. These findings, to our knowledge, have not been addressed before for this plant and have potential implications on soil remediation (phytostabilisation) and food security (minimising As in crops).