Breeding Canola (Brassica napus L.) for Protein in Feed and Food

Mapping of quantitative trait loci (QTL) in Brassica napus L. for tolerance to water stress

Brassica napus L. plants are sensitive to water stress conditions throughout their life cycle from seed germination to seed setting. This study aims at identifying quantitative trait loci (QTL) linked to B. napus tolerance to water stress mimicked by applications of 10% polyethylene glycol-6000 (PEG-6000). Two doubled haploid populations, each consisting of 150 genotypes, were used for this research. Plants at the two true leaf stage of development were grown in the absence (control) or presence (stress) of PEG-6000 under controlled environmental conditions for 48 h, and the drought stress index was calculated for each genotype. All genotypes, along with their parents, were genotyped using the Brassica Infinium 90K SNP BeadChip Array. Inclusive composite interval mapping was used to identify QTL. Six QTL and 12 putative QTL associated with water stress tolerance were identified across six chromosomes (A2, A3, A4, A9, C3, and C7). Collectively, 2154 candidate genes for water stress tolerance were identified for all the identified QTL. Among them, 213 genes were identified as being directly associated with water stress (imposed by PEG-6000) tolerance based on nine functional annotations. These results can be incorporated into future breeding initiatives to select plant material with the ability to cope effectively with water stress.

Breeding and biotechnology approaches to enhance the nutritional quality of rapeseed byproducts for sustainable alternative protein sources- a critical review

Global protein consumption is increasing exponentially, which requires efficient identification of potential, healthy, and simple protein sources to fulfil the demands. The existing sources of animal proteins are high in fat and low in fiber composition, which might cause serious health risks when consumed regularly. Moreover, protein production from animal sources can negatively affect the environment, as it often requires more energy and natural resources and contributes to greenhouse gas emissions. Thus, finding alternative plant-based protein sources becomes indispensable. Rapeseed is an important oilseed crop and the world's third leading oil source. Rapeseed byproducts, such as seed cakes or meals, are considered the best alternative protein source after soybean owing to their promising protein profile (30%-60% crude protein) to supplement dietary requirements. After oil extraction, these rapeseed byproducts can be utilized as food for human consumption and animal feed. However, anti-nutritional factors (ANFs) like glucosinolates, phytic acid, tannins, and sinapines make them unsuitable for direct consumption. Techniques like microbial fermentation, advanced breeding, and genome editing can improve protein quality, reduce ANFs in rapeseed byproducts, and facilitate their usage in the food and feed industry. This review summarizes these approaches and offers the best bio-nutrition breakthroughs to develop nutrient-rich rapeseed byproducts as plant-based protein sources.

The Brassica napus phytoglobin 1 (BnPgb1) mitigates the decrease in plant fertility resulting from high temperature stress

High temperature stress during flowering adversely affects plant fertility, decreasing plant productivity. Daily cycles of heat stress (HS), imposed on Brassica napus L. plants by slowly ramping the temperature from 23 °C to 35 °C before lowering back to pre-stress conditions, inhibited flower and silique formation, with fewer seeds per silique during the stress period, as well as decreased pollen viability. Heat stress also elevated the transcripts and protein levels of class 1 phytoglobin BnPgb1, with the protein accumulating preferentially within the anther walls. Over-expression of BnPgb1 was sufficient to attenuate the reduction in plant fertility at high temperatures while its down-regulation exacerbated the effects of HS. Relative to WT anthers, the rise in ROS and ROS-induced damage caused by HS was limited when BnPgb1 was over-expressed, and this was linked to changes in antioxidant responses. High temperatures reduced the level of ascorbic acid (AsA) in anthers by favoring its oxidation via ascorbate oxidase (AOA) and limiting its regeneration through suppression of monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR). Anthers of heat-stressed plants over-expressing BnPgb1 retained a higher AsA content with concomitant increased activities of DHAR, MDHAR, ascorbate peroxidase (APX) and superoxide dismutase (SOD). These changes suggest that BnPgb1 potentiates antioxidant responses during HS which mitigate the depression of fertility.

Predicting metabolizable energy of soybean meal and rapeseed meal from chemical composition in broilers of different ages

This study determined metabolizable energy (ME) and developed ME prediction equations for broilers based on chemical composition of soybean meal (SBM) and rapeseed meal (RSM) using a 2 × 10 factorial arrangement of age (11 to 14 or 25 to 28 d of age) and 10 sources of each ingredient. Each treatment contained 6 replicates of 8 broilers. The ME values were determined by total collection of feces and urine. Principal components analysis (PCA) of the chemical composition clearly revealed distinct differences in SBM and RSM based on a principal components (PC) score plot. The nitrogen-corrected apparent metabolizable energy (AMEn) of SBM was higher in broilers from 25 to 28 than 11 to 14 d of age (P = 0.013). Interactions between broiler age and ingredient source affected apparent metabolizable energy (AME) of SBM and ME of RSM (P < 0.05). The ME of SBM in 11 to 14 and 25 to 28-day-old broilers were estimated by crude protein (CP) content (R2≥ 0.782; SEP ≤ 83 kcal/kg DM; P < 0.001). The AME and AMEn of RSM in 11 to 14-day-old broilers were estimated by ether extract (EE), ash and acid detergent fiber (ADF) (R2 = 0.897, SEP = 106 kcal/kg DM; P = 0.002), and by EE and ash (R2 = 0.885, SEP = 98 kcal/kg DM; P = 0.001), respectively. The AME and AMEn of RSM in 25 to 28-day-old broilers were estimated by ash and ADF (R2 = 0.925, SEP = 104 kcal/kg DM; P < 0.001) and by ash and neutral detergent fiber (NDF) (R2 = 0.921, SEP = 91 kcal/kg DM; P < 0.001), respectively. These results indicate that ME of these 2 plant protein ingredients are affected interactively by chemical composition and age of broilers. This study developed robust, age-specific prediction equations of ME for broilers based on chemical composition for SBM and RSM. Overall, ME values can be predicted from CP content for SBM, or EE, ash, ADF, and NDF for RSM.

Plasma Treatment Modifies Element Distribution in Seed Coating and Affects Further Germination and Plant Growth through Interaction with Soil Microbiome

This study investigates the impact of plasma-seed interaction on germination and early plant development, focusing on Arabidopsis thaliana and Brassica napus. The investigation delves into changes in chemical composition, water absorption, and surface morphology induced by plasma filaments generated in synthetic air. These analyses were conducted using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Although plasma treatment enhanced water absorption and modified surface chemistry, its impact on germination demonstrated species- and context-dependent variations. Notably, the accelerated germination and morphogenesis of seedlings in microbiome-enriched (MB+) soil could be achieved also in microbiome-deprived (MB-) soil by short-term plasma treatment of seeds. Remarkably, the positive effects of plasma treatment on early developmental events (germination, morphogenesis) and later events (formation of inflorescences) were more pronounced in the context of MB- soil but were accompanied by a slight decrease in disease resistance, which was not detected in MB+ soil. The results underscore the intricate dynamics of plasma-plant interactions and stress the significance of accounting for the soil microbiome while designing experiments with potential field application.

Targeted editing of multiple homologues of GTR1 and GTR2 genes provides the ideal low-seed, high-leaf glucosinolate oilseed mustard with uncompromised defence and yield

Glucosinolate content in the two major oilseed Brassica crops-rapeseed and mustard has been reduced to the globally accepted Canola quality level (<30 μmoles/g of seed dry weight, DW), making the protein-rich seed meal useful as animal feed. However, the overall lower glucosinolate content in seeds as well as in the other parts of such plants renders them vulnerable to biotic challenges. We report CRISPR/Cas9-based editing of glucosinolate transporter (GTR) family genes in mustard (Brassica juncea) to develop ideal lines with the desired low seed glucosinolate content (SGC) while maintaining high glucosinolate levels in the other plant parts for uncompromised plant defence. Use of three gRNAs provided highly efficient and precise editing of four BjuGTR1 and six BjuGTR2 homologues leading to a reduction of SGC from 146.09 μmoles/g DW to as low as 6.21 μmoles/g DW. Detailed analysis of the GTR-edited lines showed higher accumulation and distributional changes of glucosinolates in the foliar parts. However, the changes did not affect the plant defence and yield parameters. When tested against the pathogen Sclerotinia sclerotiorum and generalist pest Spodoptera litura, the GTR-edited lines displayed a defence response at par or better than that of the wild-type line. The GTR-edited lines were equivalent to the wild-type line for various seed yield and seed quality traits. Our results demonstrate that simultaneous editing of multiple GTR1 and GTR2 homologues in mustard can provide the desired low-seed, high-leaf glucosinolate lines with an uncompromised defence and yield.

Characterization of novel loci controlling seed oil content in Brassica napus by marker metabolite-based multi-omics analysis

BACKGROUND

Seed oil content is an important agronomic trait of Brassica napus (B. napus), and metabolites are considered as the bridge between genotype and phenotype for physical traits.

RESULTS

Using a widely targeted metabolomics analysis in a natural population of 388 B. napus inbred lines, we quantify 2172 metabolites in mature seeds by liquid chromatography mass spectrometry, in which 131 marker metabolites are identified to be correlated with seed oil content. These metabolites are then selected for further metabolite genome-wide association study and metabolite transcriptome-wide association study. Combined with weighted correlation network analysis, we construct a triple relationship network, which includes 21,000 edges and 4384 nodes among metabolites, metabolite quantitative trait loci, genes, and co-expression modules. We validate the function of BnaA03.TT4, BnaC02.TT4, and BnaC05.UK, three candidate genes predicted by multi-omics analysis, which show significant impacts on seed oil content through regulating flavonoid metabolism in B. napus.

CONCLUSIONS

This study demonstrates the advantage of utilizing marker metabolites integrated with multi-omics analysis to dissect the genetic basis of agronomic traits in crops.

Factors Affecting the Quality of Canola Grains and Their Implications for Grain-Based Foods

Canola, Brassica napus L., is a major oilseed crop that has various uses in the food, feed, and industrial sectors. It is one of the most widely produced and consumed oilseeds in the world because of its high oil content and favorable fatty acid composition. Canola grains and their derived products, such as canola oil, meal, flour, and bakery products, have a high potential for food applications as they offer various nutritional and functional benefits. However, they are affected by various factors during the production cycle, post-harvest processing, and storage. These factors may compromise their quality and quantity by affecting their chemical composition, physical properties, functional characteristics, and sensory attributes. Therefore, it is important to optimize the production and processing methods of canola grains and their derived products to ensure their safety, stability, and suitability for different food applications. This literature review provides a comprehensive overview of how these factors affect the quality of canola grains and their derived products. The review also suggests future research needs and challenges for enhancing canola quality and its utilization in food.

Genome-Wide Identification of Brassica napus PEN1-LIKE Genes and Their Expression Profiling in Insect-Susceptible and Resistant Cultivars

Recently, it has been reported that a gene (PEN1) in Arabidopsis thaliana is highly resistant to Plutella xylostella. We screened all the homologous genes of PEN1 in Arabidopsis thaliana and found that the motif of these genes was very conserved. At present, few insect resistance genes have been identified and characterized in Brassica napus. Therefore, we screened all the homologous genes containing this motif in the Brassica napus genome and systematically analyzed the basic information, conserved domain, evolutionary relationship, chromosomal localization and expression analysis of these genes. In this study, 12 PEN1 homologous genes were identified in the Brassica napus genome, which is more than the number in Arabidopsis thaliana. These genes are unevenly distributed on the 12 chromosomes in Brassica napus. Furthermore, all the PEN1 homologous genes contained light responsiveness elements, and most of the genes contained gibberellin-responsive elements, meJA-responsive elements and abscisic-acid-responsive elements. The results will provide a theoretical basis for screening insect resistance genes from the genome of Brassica napus and analyzing the molecular mechanism of insect resistance in Brassica napus.

Multiple Functions of MiRNAs in Brassica napus L

The worldwide climate changes every year due to global warming, waterlogging, drought, salinity, pests, and pathogens, impeding crop productivity. Brassica napus is one of the most important oil crops in the world, and rapeseed oil is considered one of the most health-beneficial edible vegetable oils. Recently, miRNAs have been found and confirmed to control the expression of targets under disruptive environmental conditions. The mechanism is through the formation of the silencing complex that mediates post-transcriptional gene silencing, which pairs the target mRNA and target cleavage and/or translation inhibition. However, the functional role of miRNAs and targets in B. napus is still not clarified. This review focuses on the current knowledge of miRNAs concerning development regulation and biotic and abiotic stress responses in B. napus. Moreover, more strategies for miRNA manipulation in plants are discussed, along with future perspectives, and the enormous amount of transcriptome data available provides cues for miRNA functions in B. napus. Finally, the construction of the miRNA regulatory network can lead to the significant development of climate change-tolerant B. napus through miRNA manipulation.

Genetic variation and structural diversity in major seed proteins among and within Camelina species

Genetic variation in seed protein composition, seed protein gene expression and predictions of seed protein physiochemical properties were documented in C. sativa and other Camelina species. Seed protein diversity was examined in six Camelina species (C. hispida, C. laxa, C. microcarpa, C. neglecta, C. rumelica and C. sativa). Differences were observed in seed protein electrophoretic profiles, total seed protein content and amino acid composition between the species. Genes encoding major seed proteins (cruciferins, napins, oleosins and vicilins) were catalogued for C. sativa and RNA-Seq analysis established the expression patterns of these and other genes in developing seed from anthesis through to maturation. Examination of 187 C. sativa accessions revealed limited variation in seed protein electrophoretic profiles, though sufficient to group the majority into classes based on high MW protein profiles corresponding to the cruciferin region. C. sativa possessed four distinct types of cruciferins, named CsCRA, CsCRB, CsCRC and CsCRD, which corresponded to orthologues in Arabidopsis thaliana with members of each type encoded by homeologous genes on the three C. sativa sub-genomes. Total protein content and amino acid composition varied only slightly; however, RNA-Seq analysis revealed that CsCRA and CsCRB genes contributed > 95% of the cruciferin transcripts in most lines, whereas CsCRC genes were the most highly expressed cruciferin genes in others, including the type cultivar DH55. This was confirmed by proteomics analyses. Cruciferin is the most abundant seed protein and contributes the most to functionality. Modelling of the C. sativa cruciferins indicated that each type possesses different physiochemical attributes that were predicted to impart unique functional properties. As such, opportunities exist to create C. sativa cultivars with seed protein profiles tailored to specific technical applications.