A comparative study of convicilin storage protein gene sequences in species of the tribe Vicieae

Associating Compositional, Nutritional and Techno-Functional Characteristics of Faba Bean (Vicia faba L.) Protein Isolates and Their Production Side-Streams with Potential Food Applications

Faba beans (Vicia faba L.) show exciting prospects as a sustainable source of protein and fibre, with the potential to transition to a more sustainable food production. This study reveals the compositional, nutritional and techno-functional characteristics of two protein isolates from faba beans (Vicia faba L.), a high-starch fraction and a high-fibre side-stream. During the analysis of those four ingredients, particular attention was paid to the isolates' protein profile and the side-streams' carbohydrate composition. The isoelectric precipitated protein isolate 1 showed a protein content of 72.64 ± 0.31% DM. It exhibited low solubility but superior digestibility and high foam stability. High foaming capacity and low protein digestibility were observed for protein isolate 2, with a protein content of 71.37 ± 0.93% DM. This fraction was highly soluble and consisted primarily of low molecular weight proteins. The high-starch fraction contained 83.87 ± 3.07% DM starch, of which about 66% was resistant starch. Over 65% of the high-fibre fraction was insoluble dietary fibre. The findings of this study provide a detailed understanding of different production fractions of faba beans, which is of great value for future product development.

Seed Development and Protein Accumulation Patterns in Faba Bean (Vicia faba, L.)

A major objective in faba bean breeding is to improve its protein quality by selecting cultivars with enhanced desirable physicochemical properties. However, the protein composition of the mature seed is determined by a series of biological processes occurring during seed growth. Thus, any attempt to explain the final seed composition must consider the dynamics of the seed proteome during seed development. Here, we investigated the proteomic profile of developing faba bean seeds across 12 growth stages from 20 days after pollination (DAP) to full maturity. We analyzed trypsin-digested total protein extracts from the seeds at different growth stages by liquid chromatography-tandem mass spectrometry (LC-MS/MS), identifying 1217 proteins. The functional clusters of these proteins showed that, in early growth stages, proteins related to cell growth, division, and metabolism were most abundant compared to seed storage proteins that began to accumulate from 45 DAP. Moreover, label-free quantification of the relative abundance of seed proteins, including important globulin proteins, revealed several distinct temporal accumulation trends among the protein classes. These results suggest that these proteins are regulated differently and require further understanding of the impact of the different environmental stresses occurring at different grain filling stages on the expression and accumulation of these seed storage proteins.

Conformational Changes of Whey and Pea Proteins upon Emulsification Approached by Front-Surface Fluorescence

Proteins are widely used to stabilize emulsions, and plant proteins have raised increasing interest for this purpose. The interfacial and emulsifying properties of proteins depend largely on their molecular properties. We used fluorescence spectroscopy to characterize the conformation of food proteins from different biological origins (dairy or pea) and transformation processes (commercial or lab-made isolates) in solution and at the oil-water interface. The fourth derivative of fluorescence spectra provided insights in the local environment of tryptophan (Trp) residues and thus in the protein structure. In emulsions, whey proteins adsorbed with their Trp-rich region at the oil-water interface. Proteins in the commercial pea isolate were present as soluble aggregates, and no changes in the local environment of the Trp residues were detected upon emulsification, suggesting that these structures adsorb without conformational changes. The lab-purified pea proteins were less aggregated and a Trp-free region of the vicilin adsorbed at the oil-water interface.

Fava bean (Vicia faba L.) for food applications: From seed to ingredient processing and its effect on functional properties, antinutritional factors, flavor, and color

The food industry, along with the consumers, is interested in plant-based diet because of its health benefits and environmental sustainability. Vicia faba L. (V. faba) is a promising source of pulse proteins for the human diet and can yield potential nutritional and functional ingredients, namely, flours, concentrates, and isolates, which are relevant for industrial food applications. Different processes produce and functionalize V. faba ingredients relevant for industrial food applications, along with various alternatives within each unit operation used in their production. Processing modifies functional properties of the ingredients, which can occur by (i) changing in overall nutritional composition after processing steps and/or (ii) modifying the structure and conformation of protein and of other components present in the ingredients. Furthermore, V. faba limitations due to off-flavor, color, and antinutritional factors are influenced by ingredient production and processing that play a significant role in their consumer acceptability in foods. This review attempts to elucidate the influence of different ways of processing on the functional, sensory, and safety aspects of V. faba L. ingredients, highlighting the need for further research to better understand how the food industry could improve their utilization in the market.

Identification and Quantification of Major Faba Bean Seed Proteins

Faba bean (Vicia faba L.) holds great importance for human and animal nutrition for its high protein content. However, better understanding of its seed protein composition is required in order to develop cultivars that meet market demands for plant proteins with specific quality attributes. In this study, we screened 35 diverse Vicia faba genotypes by employing the one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (1D SDS-PAGE) method, and 35 major protein bands obtained from three genotypes with contrasting seed protein profiles were further analyzed by mass spectrometry (MS). Twenty-five of these protein bands (MW range: ∼ 9-107 kDa) had significant (p ≤ 0.05) matches to polypeptides in protein databases. MS analysis showed that most of the analyzed protein bands contained more than one protein type and, in total, over 100 proteins were identified. These included major seed storage proteins such as legumin, vicilin, and convicilin, as well as other protein classes like lipoxygenase, heat shock proteins, sucrose-binding proteins, albumin, and defensin. Furthermore, seed protein extracts were separated by size-exclusion high-performance liquid chromatography (SE-HPLC), and percentages of the major protein classes were determined. On average, legumin and vicilin/convicilin accounted for 50 and 27% of the total protein extract, respectively. However, the proportions of these proteins varied considerably among genotypes, with the ratio of legumin:vicilin/convicilin ranging from 1:1 to 1:3. In addition, there was a significant (p < 0.01) negative correlation between the contents of these major fractions (r = -0.83). This study significantly extends the number of identified Vicia faba seed proteins and reveals new qualitative and quantitative variation in seed protein composition, filling a significant gap in the literature. Moreover, the germplasm and screening methods presented here are expected to contribute in selecting varieties with improved protein content and quality.

Isolation and characterization of Korean pine (Pinus koraiensis) convicilin

A vicilin-like globulin seed storage protein, termed convicilin, was isolated for the first time from Korean pine (Pinus koraiensis). SDS-PAGE analysis revealed that Korean pine convicilin was post-translationally processed. The N-terminal peptide sequences of its components were determined. These peptides could be mapped to a protein translated from an embryo abundant transcript isolated in this study. Similar to vicilin, native convicilin appeared to be homotrimeric. Differential scanning calorimetry (DSC) analyses revealed that this protein is less resistant to thermal treatment than Korean pine vicilin. Its transition temperature was 75.57 °C compared with 84.13 °C for vicilin. The urea induced folding-unfolding equilibrium of pine convicilin monitored by intrinsic fluorescence could be interpreted in terms of a two-state model, with a Cm of 4.41 ± 0.15 M.

Lathyrus diversity: available resources with relevance to crop improvement--L. sativus and L. cicera as case studies

BACKGROUND

The Lathyrus genus includes 160 species, some of which have economic importance as food, fodder and ornamental crops (mainly L. sativus, L. cicera and L. odoratus, respectively) and are cultivated in >1·5 Mha worldwide. However, in spite of their well-recognized robustness and potential as a source of calories and protein for populations in drought-prone and marginal areas, cultivation is in decline and there is a high risk of genetic erosion.

SCOPE

In this review, current and past taxonomic treatments of the Lathyrus genus are assessed and its current status is examined together with future prospects for germplasm conservation, characterization and utilization. A particular emphasis is placed on the importance of diversity analysis for breeding of L. sativus and L. cicera.

CONCLUSIONS

Efforts for improvement of L. sativus and L. cicera should concentrate on the development of publicly available joint core collections, and on high-resolution genotyping. This will be critical for permitting decentralized phenotyping. Such a co-ordinated international effort should result in more efficient and faster breeding approaches, which are particularly needed for these neglected, underutilized Lathyrus species.

Amaranth (Amaranthus hypochondriacus) vicilin subunit structure

The 7S-globulin fraction is a minor component of the amaranth storage proteins. The present work provides new information about this protein. The amaranth 7S-globulin or vicilin presented a sedimentation coefficient of 8.6 ± 0.6 S and was composed of main subunits of 66, 52, 38, and 16 kDa. On the basis of mass spectrometry (MS) analysis of tryptic fragments, the 52, 38, and 16 kDa subunits presented sequence homology with sesame vicilin, whereas the 66 kDa subunit showed sequence similarity with a putative vicilin. Several characteristics of the 66 kDa subunit were similar to members of the convicilin family. Results support the hypothesis that the 7S-globulin molecules are composed of subunits coming from at least two gene families with primary products of 66 and 52 kDa, respectively. According to the present information, amaranth vicilin may be classified into the vicilin group that includes pea, broad bean, and sesame vicilins, among others.

The proteome of seed development in the model legume Lotus japonicus

We have characterized the development of seeds in the model legume Lotus japonicus. Like soybean (Glycine max) and pea (Pisum sativum), Lotus develops straight seed pods and each pod contains approximately 20 seeds that reach maturity within 40 days. Histological sections show the characteristic three developmental phases of legume seeds and the presence of embryo, endosperm, and seed coat in desiccated seeds. Furthermore, protein, oil, starch, phytic acid, and ash contents were determined, and this indicates that the composition of mature Lotus seed is more similar to soybean than to pea. In a first attempt to determine the seed proteome, both a two-dimensional polyacrylamide gel electrophoresis approach and a gel-based liquid chromatography-mass spectrometry approach were used. Globulins were analyzed by two-dimensional polyacrylamide gel electrophoresis, and five legumins, LLP1 to LLP5, and two convicilins, LCP1 and LCP2, were identified by matrix-assisted laser desorption ionization quadrupole/time-of-flight mass spectrometry. For two distinct developmental phases, seed filling and desiccation, a gel-based liquid chromatography-mass spectrometry approach was used, and 665 and 181 unique proteins corresponding to gene accession numbers were identified for the two phases, respectively. All of the proteome data, including the experimental data and mass spectrometry spectra peaks, were collected in a database that is available to the scientific community via a Web interface (http://www.cbs.dtu.dk/cgi-bin/lotus/db.cgi). This database establishes the basis for relating physiology, biochemistry, and regulation of seed development in Lotus. Together with a new Web interface (http://bioinfoserver.rsbs.anu.edu.au/utils/PathExpress4legumes/) collecting all protein identifications for Lotus, Medicago, and soybean seed proteomes, this database is a valuable resource for comparative seed proteomics and pathway analysis within and beyond the legume family.