Chickpea – nutritional quality and role in alleviation of global malnourishment

Chickpea (Cicer arietinum L.) constitute a well-balanced source of carbohydrates, proteins, vitamins and minerals essential to combat malnourishment in human populations. The various seed constituents show large variations in abundance between genotypes, which allow selection of lines for both calorie-rich and calorie-reduced diets. Chickpea with a high protein content combined with high digestibility is preferred in diets where food is scarce. In diets of affluent cultures, chickpeas with good vitamin, fatty acid and mineral balance combined with low digestibility would have a preference. The major challenges in chickpea improvement are development of region-specific genotypes with reduced content of anti-nutritional constituents such as the raffinose family of oligosaccharides. This improvement would encourage a wider use of chickpea-based diets around the world

Co-localization of genomic regions associated with seed morphology and composition in a desi chickpea (Cicer arietinum L.) population varying in seed protein concentration

Key message Major QTL on LG 1 and 3 control seed filling and seed coat development, thereby affecting seed shape, size, color, composition and weight, key determinants of crop yield and quality. Abstract A chickpea (Cicer arietinum L.) population consisting of 189 recombinant inbred lines (RILs) derived from a cross between medium-protein ICC 995 and high-protein ICC 5912 genotypes of the desi market class was analyzed for seed properties. Seed from the parental lines and RILs was produced in four different environments for determination of seed shape (SS), 100-seed weight (100-SW), protein (PRO) and starch (STA) concentration. Polymorphic genetic markers for the population were identified by Genotyping by Sequencing and assembled into a 522.5 cM genetic map. Phenotype data from the different growth environments were analyzed by QTL mapping done by single and multi-environment analyses and in addition, single marker association mapping. The analyses identified in total 11 QTL, of which the most significant (P < 0.05) loci were located on LG 1 (q-1.1), LG 2 (q-2.1), LG 3 (q-3.2, q-3.3), LG 4 (q-4.2), and LG 5 (q-5.1). STA was mostly affected by q-1.1, which explained 19.0% of the phenotypic variance for the trait. The largest QTL effects were demonstrated by q-3.2 that explained 52.5% of the phenotypic variances for 100-SW, 44.3% for PRO, and 14.6% for SS. This locus was also highly associated with flower color (COL; 95.2% explained) and showed q-3.2 alleles from the ICC 5912 parent conferred the blue flower color and production of small, round seeds with relatively high protein concentration. Genes affecting seed filling at q-1.1 and seed coat development at q-3.2, respectively, were considered to underlie differences in seed composition and morphology in the RIL population

Variation in Seed-Quality Traits of Chickpea and Their Correlation to Raffinose Family Oligosaccharides Concentrations

Genetic resources with desired seed composition are needed to improve nutritional quality of chickpea (Cicer arietinum L.) seeds. A germplasm collection of 171 chickpea genotypes (desi and kabuli types) was characterized for selected seed quality traits (thousand-seed weight [TSW], starch, protein, and amylose) in one greenhouse and two field trials. Kabuli-type chickpea genotypes (115.7 to 537.4 g and 36.2 to 49.0%) had higher TSW and starch concentrations than desi types (114.6 to 332.4 g and 32.4 to 42.9%), respectively. Desi type chickpea genotypes (16.7 to 27.5%) showed a higher range for protein concentration than kabuli types (17.1 to 24.8%). However, amylose concentration did not vary significantly between desi (29.7 to 34.4%) and kabuli (29.2 to 35.0%) type chickpea genotypes. Genotype, environment, and their interaction showed a significant impact on selected seed-quality traits. Among the chickpea seed-quality traits studied, seed weight was the most heritable trait, and it showed significant positive correlation with starch concentration. Protein, amylose, and total raffinose family oligosaccharides (RFO) had significant negative correlation with TSW. However, total RFO concentration showed significant positive correlation to both starch and protein concentrations. The identified desi and kabuli genotypes can be used as new genetic resources in chickpea improvement programs to develop chickpea varieties with enhanced nutritional composition

Variation in important seed constituents among various chickpea genotypes

Chickpea (Cicer arietinum L.) is the third most important pulse crop and an excellent source of protein in the human diet (Garg et al., 2011). However, the presence of anti-nutritional factors like the raffinose family oligosaccharides (RFO) restrains its acceptability as food and feed (Olmedilla Alonso et al., 2010). Higher concentration of RFO in chickpea seeds affects human health negatively and plays an important physiological role in plants (Martinez-Villaluenga et al., 2008). Hence, there is a need to reduce RFO concentration in seeds without affecting plant growth. To achieve this objective, it is imperative to understand the biochemical mechanism and genetic basis of the RFO biosynthetic pathway. As a first step, we studied the variation in RFO concentration along with starch and protein in a germplasm collection of 152 genotypes. These genotypes were grown in the field for two consecutive years 2009 and 2010 at ICRISAT in India and in greenhouse in 2010 at the University of Saskatchewan, Canada. Enzymatic methods using commercial kits (Megazyme International) were used to determine starch and total RFO concentration. Protein concentration was determined by FP-528 Protein/Nitrogen Analyzer (Leco). To determine individual RFO profiles, we have developed a new high performance anion exchanged chromatography based gradient method. Results showed that lentil genotypes from greenhouse cultivation had significantly lower (1.58–4.67 mmoles/100 g-1) concentration of total RFO than that of their field grown counterparts. Stachyose was identified as a major RFO in chickpea seeds followed by raffinose and verbascose. Individual RFOs (raffinose, stachyose and verbascose) showed higher concentration in the ICRISAT 2009 set than that of the ICRiSAT 2010 and greenhouse sets. An obvious strong positive correlation was found among total RFO and individual members of the family. Starch concentration in chickpea genotypes ranged from 25.7 to 50.7% of total seed weight. ICRISAT 2009 set (29.4–50.7%) had a higher amount of starch than that in ICRISAT 2010 (25.7–44.5%) and the greenhouse set (28.2–44.4%). Starch concentration showed a positive correlation with total RFO. The chickpea seeds have 13.5–31.7% protein. Genotypes in the ICRISAT 2010 set had a higher amount of protein (17.92–31.73%) compared to the ICRISAT 2009 and greenhouse sets. A significant negative correlation was observed between protein and starch concentration. Analysis of variance revealed a significant effect (P < 0.001) of genotype, environment and genotype x environment on chickpea seed constituents. This study has revealed the RFO variation in chickpea genotypes and its correlation with other important seed constituents. These findings will be helpful in genotype screening for contrasting RFO concentration and in exploring the RFO biosynthetic pathway

Calcium phosphate nanoparticles as intrinsic inorganic antimicrobials: In search of the key particle property

One of the main goals of materials science in the 21st century is the development of materials with rationally designed properties as substitutes for traditional pharmacotherapies. At the same time, there is a lack of understanding of the exact material properties that induce therapeutic effects in biological systems, which limits their rational optimization for the related medical applications. This study sets the foundation for a general approach for elucidating nanoparticle properties as determinants of antibacterial activity, with a particular focus on calcium phosphate nanoparticles. To that end, nine physicochemical effects were studied and a number of them were refuted, thus putting an end to frequently erred hypotheses in the literature. Rather than having one key particle property responsible for eliciting the antibacterial effect, a complex synergy of factors is shown to be at work, including (a) nanoscopic size; (b) elevated intracellular free calcium levels due to nanoparticle solubility; (c) diffusivity and favorable electrostatic properties of the nanoparticle surface, primarily low net charge and high charge density; and (d) the dynamics of perpetual exchange of ultrafine clusters across the particle/solution interface. On the positive side, this multifaceted mechanism is less prone to induce bacterial resistance to the therapy and can be a gateway to the sphere of personalized medicine. On a more problematic side, it implies a less intense effect compared to single-target molecular therapies and a difficulty of elucidating the exact mechanisms of action, while also making the rational design of theirs for this type of medical application a challenge

New Structural and Functional Contexts of the Dx[DN]xDG Linear Motif: Insights into Evolution of Calcium-Binding Proteins

Binding of calcium ions (Ca2+) to proteins can have profound effects on their structure and function. Common roles of calcium binding include structure stabilization and regulation of activity. It is known that diverse families – EF-hands being one of at least twelve – use a Dx[DN]xDG linear motif to bind calcium in near-identical fashion. Here, four novel structural contexts for the motif are described. Existing experimental data for one of them, a thermophilic archaeal subtilisin, demonstrate for the first time a role for Dx[DN]xDG-bound calcium in protein folding. An integrin-like embedding of the motif in the blade of a β-propeller fold – here named the calcium blade – is discovered in structures of bacterial and fungal proteins. Furthermore, sensitive database searches suggest a common origin for the calcium blade in β-propeller structures of different sizes and a pan-kingdom distribution of these proteins. Factors favouring the multiple convergent evolution of the motif appear to include its general Asp-richness, the regular spacing of the Asp residues and the fact that change of Asp into Gly and vice versa can occur though a single nucleotide change. Among the known structural contexts for the Dx[DN]xDG motif, only the calcium blade and the EF-hand are currently found intracellularly in large numbers, perhaps because the higher extracellular concentration of Ca2+ allows for easier fixing of newly evolved motifs that have acquired useful functions. The analysis presented here will inform ongoing efforts toward prediction of similar calcium-binding motifs from sequence information alone

Genotype and Growing Environment Interaction Shows a Positive Correlation between Substrates of Raffinose Family Oligosaccharides (RFO) Biosynthesis and Their Accumulation in Chickpea (Cicer arietinum L.) Seeds

To develop genetic improvement strategies to modulate raffinose family oligosaccharides (RFO) concentration in chickpea (Cicer arietinum L.) seeds, RFO and their precursor concentrations were analyzed in 171 chickpea genotypes from diverse geographical origins. The genotypes were grown in replicated trials over two years in the field (Patancheru, India) and in the greenhouse (Saskatoon, Canada). Analysis of variance revealed a significant impact of genotype, environment, and their interaction on RFO concentration in chickpea seeds. Total RFO concentration ranged from 1.58 to 5.31 mmol/100 g and from 2.11 to 5.83 mmol/100 g in desi and kabuli genotypes, respectively. Sucrose (0.60−3.59 g/100 g) and stachyose (0.18−2.38 g/ 100 g) were distinguished as the major soluble sugar and RFO, respectively. Correlation analysis revealed a significant positive correlation between substrate and product concentration in RFO biosynthesis. In chickpea seeds, raffinose, stachyose, and verbascose showed a moderate broad sense heritability (0.25−0.56), suggesting the use of a multilocation trials based approach in chickpea seed quality improvement programs

Edge excitation red-shift and excited-state proton association in acridine

Acridine in methanol shows an edge excitation red-shift. On shorter-wavelength excitation the emission from acridine is observed, while on red edge excitation the emission corresponds to acridinium. At room temperature the shift is abrupt with no effect of viscosity and solvent deuteration; however, at 80 K a slightly less abrupt shift is observed. The excited-state proton association is found to be wavelength-dependent. It seems that at room temperature with red edge excitation, protonation in the excited state is fast compared to the lifetime of the excited state, while the excess energy with shorter wavelength excitation may lead to non-promoting modes such that the proton transfer does not take place