Advances in Crop Improvement and Delivery Research for Nutritional Quality and Health Benefits of Groundnut (Arachis hypogaea L.)

Groundnut is an important global food and oil crop that underpins agriculture-dependent livelihood strategies meeting food, nutrition, and income security. Aflatoxins, pose a major challenge to increased competitiveness of groundnut limiting access to lucrative markets and affecting populations that consume it. Other drivers of low competitiveness include allergens and limited shelf life occasioned by low oleic acid profile in the oil. Thus grain off-takers such as consumers, domestic, and export markets as well as processors need solutions to increase profitability of the grain. There are some technological solutions to these challenges and this review paper highlights advances in crop improvement to enhance groundnut grain quality and nutrient profile for food, nutrition, and economic benefits. Significant advances have been made in setting the stage for marker-assisted allele pyramiding for different aflatoxin resistance mechanisms—in vitro seed colonization, pre-harvest aflatoxin contamination, and aflatoxin production—which, together with pre- and post-harvest management practices, will go a long way in mitigating the aflatoxin menace. A breakthrough in aflatoxin control is in sight with overexpression of antifungal plant defensins, and through host-induced gene silencing in the aflatoxin biosynthetic pathway. Similarly, genomic and biochemical approaches to allergen control are in good progress, with the identification of homologs of the allergen encoding genes and development of monoclonal antibody based ELISA protocol to screen for and quantify major allergens. Double mutation of the allotetraploid homeologous genes, FAD2A and FAD2B, has shown potential for achieving >75% oleic acid as demonstrated among introgression lines. Significant advances have been made in seed systems research to bridge the gap between trait discovery, deployment, and delivery through innovative partnerships and action learning

G × E interactions in QTL introgression lines of Spanish-type groundnut (Arachis hypogaea L.)

Multi-environment testing at five locations for rust and late leaf spot (LLS) resistance with 41 introgressed lines (ILs) bred using marker-assisted backcross breeding in the genetic background Spanish- type groundnut varieties identified significant genotype, and genotype 9 environment interactions (GEI) for LLS disease resistance and yield parameters. Significant GEI effects suggest the need to identify location specific breeding lines to achieve gains in pod yield and LLS resistance. The observed variable LLS disease reaction among the ILs in part suggests influence of background genotype on the level of resistance. A breeding scheme with early generation selection using molecular markers followed by phenotyping for LLS, and multi-location testing of fixed breeding lines was optimized to enhance selection intensity and accuracy in groundnut breeding. The ILs, ICGVs 14431, 14436 and 14438 with pooled LLS score at 90 DAS of 3.5–3.7 were superior to respective recurrent parent for pod yield, with early maturing similar to recurrent parents. The pod yield advantage in ILs is attributed by more number of pods, besides resistance to LLS that contributes to better filling

Genomic Tools in Groundnut Breeding Program: Status and Perspectives

Groundnut, a nutrient-rich food legume, is cultivated world over. It is valued for its good quality cooking oil, energy and protein rich food, and nutrient-rich fodder. Globally, groundnut improvement programs have developed varieties to meet the preferences of farmers, traders, processors, and consumers. Enhanced yield, tolerance to biotic and abiotic stresses and quality parameters have been the target traits. Spurt in genetic information of groundnut was facilitated by development of molecular markers, genetic, and physical maps, generation of expressed sequence tags (EST), discovery of genes, and identification of quantitative trait loci (QTL) for some important biotic and abiotic stresses and quality traits. The first groundnut variety developed using marker assisted breeding (MAB) was registered in 2003. Since then, USA, China, Japan, and India have begun to use genomic tools in routine groundnut improvement programs. Introgression lines that combine foliar fungal disease resistance and early maturity were developed using MAB. Establishment of marker-trait associations (MTA) paved way to integrate genomic tools in groundnut breeding for accelerated genetic gain. Genomic Selection (GS) tools are employed to improve drought tolerance and pod yield, governed by several minor effect QTLs. Draft genome sequence and low cost genotyping tools such as genotyping by sequencing (GBS) are expected to accelerate use of genomic tools to enhance genetic gains for target traits in groundnut

Genotyping-by-sequencing based genetic mapping reveals large number of epistatic interactions for stem rot resistance in groundnut

Key message Genetic mapping identified large number of epistatic interactions indicating the complex genetic architecture for stem rot disease resistance. Abstract Groundnut (Arachis hypogaea) is an important global crop commodity and serves as a major source of cooking oil, diverse confectionery preparations and livestock feed. Stem rot disease caused by Sclerotium rolfsii is the most devastating disease of groundnut and can cause up to 100% yield loss. Genomic-assisted breeding (GAB) has potential for accelerated development of stem rot resistance varieties in short period with more precision. In this context, linkage analysis and quantitative trait locus (QTL) mapping for resistance to stem rot disease was performed in a bi-parental recombinant inbred line population developed from TG37A (susceptible) × NRCG-CS85 (resistant) comprising of 270 individuals. Genotyping-by-sequencing approach was deployed to generate single nucleotide polymorphism (SNP) genotyping data leading to development of a genetic map with 585 SNP loci spanning map distance of 2430 cM. QTL analysis using multi-season phenotyping and genotyping data could not detect any major main-effect QTL but identified 44 major epistatic QTLs with phenotypic variation explained ranging from 14.32 to 67.95%. Large number interactions indicate the complexity of genetic architecture of resistance to stem rot disease. A QTL of physical map length 5.2 Mb identified on B04 comprising 170 different genes especially leucine reach repeats, zinc finger motifs and ethyleneresponsive factors, etc., was identified. The identified genomic regions and candidate genes will further validate and facilitate marker development to deploy GAB for developing stem rot disease resistance groundnut varieties

Understanding the switchable solvent extraction of phospholipids from dairy by-products

Switchable solvents have been used for the extraction and subsequent separation of polar compounds. These solvents represent a new class of solvents having the capacity to change their polarity with an external stimulus. Recently, we have used a tertiary amine (N,N-dimethylcyclohexylamine, CyNMe2) as a switchable hydrophilicity solvent (SHS) for extracting phospholipids from different dairy matrices. The underlying principle behind the change in polarity is due to the formation of ammonium carbonate salt in the presence of CO2 . Upon removing the CO2 with nitrogen, the carbonate salt returns back to its original amine. Unfortunately, the extraction mechanism by which CyNMe2 acts is largely unknown, which may limit its further development. In this work, we extracted PLs from buttermilk and B-serum by CyNMe2. In addition, the extraction was systematically studied in terms of yield of PLs, gel electrophoresis, particle size, scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM). For comparison, the PLs were also extracted using Folch extraction. For buttermilk, the extraction of PLs by CyNMe2 resulted in yields remarkably higher (significantly different P \u3c 0.05 according to Tukey’s test) than the control treatment (99.96 ± 1.21 and 11.37 ± 2.31%, respectively). Similarly, the recovered PLs in B-serum by CyNMe2 (7.57 ± 0.59%) were significantly different (P \u3c 0.05 according to Tukey’s test) by then the control extraction (5.34 ± 0.61%). Analysis of gel electrophoresis revealed some degree of disruption of the protein matrix, being more extensive in the case of SHS. Images through CLSM of untreated samples showed aggregates of fat and protein entrapped, while the use of CyNMe2 resulted in disruption of such aggregates. Additionally, SEM images revealed the separation of the lipids from the protein network with the extraction by CyNMe2. Our results indicate that the extraction of PLs from buttermilk and B-serum is mainly ascribed to protein disruption, which may release the PLs into the aqueous medium. The outcomes of this study help to gain insights into the extraction mechanism by which CyNMe2 acts, and develop extraction strategies for protein matrices

Application of beta-serum in ice cream manufacturing

Beta-serum (BS) is the aqueous product (serum) produced after the phase inversion during the manufacture of anhydrous milk fat. Although its gross composition resembles that of nonfat dry milk (NFDM), BS contains about 6–8% of phospholipids (PLs) on dry basis. Such con- centration of PLs may improve the emulsification during ice cream. The objective of this work was to evaluate the effect of BS on selected quality parameters of ice cream. A secondary objective was to moni- tor the presence of PLs within the serum phase at different processing steps of ice cream manufacture, including mixing, pasteurization, freezing, and melting. An ice cream formulated with NFDM was used as a control treatment. Ice cream mix formulated with and without BS was centrifuged (4,000 rpm for 30 min) to separate the serum phase (upper phase) and solid phase (lower phase), which were analyzed for total lipids and total phospholipids. Additionally, the presence of PLs in both phases was monitored through confocal laser scanning micros- copy. Overall, the majority of PLs were found at the bottom phase during mixing, pasteurization, and melting. The particle size and zeta potential measurements were observed to be 474.6 ± 13.21 and 564.8 ± 12.7 nm, −37.9 ± 5.90 and −43.1 ± 4.90 mV for the control ice cream and B-serum ice cream, respectively. The PLs reported after meltdown using a sieve (0.833mm) for IC control and B-serum were 58.03 ± 4.10 and 63.47 ± 3.02%, respectively, while before meltdown it was reported 4.04 ± 1.49 and 11.27 ± 0.56%, respectively. The flow cure indicated a shear-thinning behavior for both samples. Therefore, results document the presence of PLs in the manufacturing of ice cream and significant quality attributes in ice cream with the addition of beta-serum

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Extraction of dairy phospholipids using switchable solvents: A feasibility study

Phospholipids (PLs) are found as lipid bilayers in all plant and animals cells membranes. Dairy PLs are located in the milk fat globule membrane, and they account for about 1–4% of the total milk fat depending on the season and lactation stage. The consumption of PLs has been associated with numerous health benefits including reducing heart disease, cholesterol adsorption, and improved immunological functions. Dairy foods and their byproducts represent a natural source of PLs with great potential for isolation and further commercialization. The current extraction of dairy PLs involves various steps (concentration, solvent separation, lipid recovery and fractionation) within the entire process, which results in low overall efficiency and economically unviable. This study aimed at evaluating the feasibility of a primary amine (N,N-dimethylcyclohexylamine) as a switchable hydrophilicity solvent (SHS) for extracting dairy PLs. For comparison, PLs were also extracted using the Folch method (FM) consisted of chloroform and methanol mixture, and Mojonnier method (MM). PLs were extracted from 4 different matrix (raw cream, buttermilk, b-serum and buttermilk concentrate), and they were qualitatively characterized by thin layer chromatography. The extraction was performed at room temperature using different SHS ratios (3/1, 6/1, and 12/1 wt/wt). After extraction, the solvent was removed from the extract by bubbling CO2 at atmospheric pressure. The lipid yield obtained from SHS method for raw cream was found to be higher (28.9 ± 1.3%) than FM and MM, 27.4 ± 1.6% and 29.2 ± 1.3%, respectively. Contrary, higher values of lipid yield were obtained for buttermilk, concentrated buttermilk, and B-serum using MM. Interestingly, the recovered fraction of PLs using the SHS extraction at a ratio of 12/1 was substantially higher than FM and MM. The recovered fraction of PLs for raw cream, b-serum, and buttermilk concentrated were 0.33, 7.5, 77.2, and 99.9%, respectively. These results demonstrated the feasibility of using SHS such as N,Ndimethylcyclohexylamine for the extraction of dairy PLs

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