Triterpene Alcohols and Sterols in the Seeds of Brassica napus

Nine triterpene alcohols, sixteen 4α-methylsterols and ten 4-desmethylsterols were identified in the unsaponifiable matter of the seed oil of Brassica napus (Cruciferae). The occurrence of three Δ⁸-lanostane triterpenes, which are unusual in higher plants, i.e., lanost-8-en-3β-ol, lanosterol and 24-methylenelanost-8-en-3α-ol, besides the corresponding 9β,19-cyclopropyl isomers, is of significance.     

Discovery of Genomic Regions and Candidate Genes Controlling Root Development Using a Recombinant Inbred Line Population in Rapeseed (Brassica napus L.)

Marker-assisted selection enables breeders to quickly select excellent root architectural variations, which play an essential role in plant productivity. Here, ten root-related and shoot biomass traits of a new F₆ recombinant inbred line (RIL) population were investigated under hydroponics and resulted in high heritabilities from 0.61 to 0.83. A high-density linkage map of the RIL population was constructed using a Brassica napus 50k Illumina single nucleotide polymorphism (SNP) array. A total of 86 quantitative trait loci (QTLs) explaining 4.16–14.1% of the phenotypic variances were detected and integrated into eight stable QTL clusters, which were repeatedly detected in different experiments. The codominant markers were developed to be tightly linked with three major QTL clusters, qcA09-2, qcC08-2, and qcC08-3, which controlled both root-related and shoot biomass traits and had phenotypic contributions greater than 10%. Among these, qcA09-2, renamed RT.A09, was further fine-mapped to a 129-kb interval with 19 annotated genes in the B. napus reference genome. By integrating the results of real-time PCR and comparative sequencing, five genes with expression differences and/or amino acid differences were identified as important candidate genes for RT.A09. Our findings laid the foundation for revealing the molecular mechanism of root development and developed valuable markers for root genetic improvement in rapeseed.     

Ability of honeybee,Apis mellifera,to detect and discriminate odors of varieties of canola (Brassica rapa and Brassica napus) and snapdragon flowers (Antirrhinum majus)

Honeybees (Apis mellifera) use odors to identify and discriminate among flowers during foraging. This series of experiments examined the ability of bees to detect and discriminate among the floral odors of different varieties of two species of canola (Brassica rapa and Brassica napus) and also among three varieties of snapdragons (Antirhinnum majus). Individual worker honeybees were trained using a proboscis extension assay. The ability of bees to distinguish a floral odor from an air stimulus during training increased as the number of flowers used during training increased. Bees conditioned to the odor of one variety of flower were asked to discriminate it from the odors of other flowers in two different training assays. Bees were unable to discriminate among flowers at the level of variety in a randomized presentation of a reinforced floral odor and an unreinforced floral odor. In the second type of assay, bees were trained with one floral variety for 40 trials without reinforcement and then tested with the same variety or with other varieties and species. If a bee had been trained with a variety of canola, it was unable to differentiate the odor of one canola flower from the odor of other canola flowers, but it could differentiate canola from the odor of a snapdragon flower. Bees trained with the odor of snapdragon flowers readily differentiated the odor of one variety of a snapdragon from the odor of other varieties of snapdragons and also canola flowers. Our study suggests that both intensity and odor quality affect the ability of honeybees to differentiate among floral perfumes.     

Evaluation of bio-char as porous catalyst support in the pyrolysis of Brassica napus subsp. napus cake

Journal of Porous Materials - It is very important to produce carbonaceous porous material from sustainable biomass resource and to investigate its different application areas. In this study, it...     

Environmental and Developmental Regulation of Trypsin Inhibitor Activity in Brassica napus

We examined several environmental and developmental influences on trypsin inhibitor (TI) activity in leaves of young Brassica napus seedlings in a series of greenhouse experiments. In seedlings of B. napus cv. Westar, TI activity is constitutively present and exhibits a rise then fall through time in the first true leaves of young plants. TI activity is induced by wounding in the first true leaves, but the degree of induction is relatively insensitive to the degree of wounding over a gradient of 5–15% of leaf area damage. TI activity is enhanced in first true leaves of plants in which the cotyledons have been wounded relative to plants in which the cotyledons have not been wounded. TI activity is also enhanced in the second true leaves on plants in which the first true leaves have been wounded. The degree of systemic induction in second true leaves declines additively with plant age, but local induction in the first true leaves is not affected by age. In B. napus cv. Gido, TI activity is constitutively present but is not locally wound-inducible in first true leaves of young plants exposed to the same wounding gradient as cv. Westar. In unwounded plants at the six-leaf stage, TI activity is higher in second true leaves than in fifth true leaves, indicating that TI activity is developmentally regulated in this cultivar.     

The Flavonoid Biosynthesis and Regulation in Brassica napus: A Review

Brassica napus is an important crop for edible oil, vegetables, biofuel, and animal food. It is also an ornamental crop for its various petal colors. Flavonoids are a group of secondary metabolites with antioxidant activities and medicinal values, and are important to plant pigmentation, disease resistance, and abiotic stress responses. The yellow seed coat, purple leaf and inflorescence, and colorful petals of B. napus have been bred for improved nutritional value, tourism and city ornamentation. The putative loci and genes regulating flavonoid biosynthesis in B. napus have been identified using germplasms with various seed, petal, leaf, and stem colors, or different flavonoid contents under stress conditions. This review introduces the advances of flavonoid profiling, biosynthesis, and regulation during development and stress responses of B. napus, and hopes to help with the breeding of B. napus with better quality, ornamental value, and stress resistances.     

Trierucoylglycerol Biosynthesis in Transgenic Plants of Rapeseed (Brassica napus L.)

The erucoyl-CoA specific sn-1-acylglycerol-3-phosphate acyltransferase (LPAAT) of Limnanthes douglasii was functionally expressed in developing seeds of differing high-erucic acid rapeseed genotypes, namely resynthesized lines and cultivars. Lipid analysis revealed that seed oil of transgenic plants in contrast to that of control plants contained trierucoylglycerol as well as a molecular species with two erucoyl groups and one eicosenoyl group. The proportion of trierucoylglycerol was distinctly higher in the seeds from transgenic resynthesized plants than in those from transgenic cultivars. In pooled seed oil fractions, up to 9% trierucoylglycerol (trierucin) was determined and the fatty acid composition at the sn-2 position was found to consist of more than 40% erucic acid. Since the pooled seeds were segregating for the presence of the L. douglasii gene, the analysis of single seeds gave even higher levels of up to 13% trierucin.     

Effect of age and cholestyramine feeding on rat liver 3-hydroxy-3-methyl glutaryl CoA reductase,sterol carrier protein 1 and sterol carrier protein 2 activities

The rate of formation of sterol from squalene in livers from suckling rats was less than one-third that of adults. This difference was due to a lesser activity of microsomal enzymes in the suckling rat livers, and not to any difference in cytosolic sterol carrier protein 1. The microsomal enzymes and sterol carrier protein 2 of the cytosol required for the conversion 7-dehydrocholesterol to cholesterol were both lower in suckling rats compared to adults. Both those activities paralleled the differences in HMG-CoA reductase activities between suckling and adult rats. Feeding of cholestryamine to adult rats increased the activities of the microsomal enzymes, sterol carrier protein 1 and sterol carrier protein 2 involved in the conversion of squalene to cholesterol.     

Characterization of chlorophyll pigments in ripening canola seed (Brassica napus)

This study characterizes the chlorophyll pigments in ripeningBrassica napus seed. Seed samples, collected weekly as the crop ripened, were analyzed by high-performance liquid chromatography to characterize chlorophyll pigment composition. Chlorophyll A, chlorophyll B, pheophytin A and pheophytin B were the predominant pigments, while pheophorbide A, methylpheophorbide A and pyropheophytin A were minor components. No differences in pigment composition were observed between the three cultivars tested or between early and late seeding dates. There were differences in pigment composition between the two years of the study, which may result either from seed aging during storage or from environmental influences. Pigment composition was dependent on seed maturity, with physiologically mature green seeds containing both chlorophylls and pheophytins, but fully mature seeds containing only chlorophylls. Pheophytins and the minor components appeared transiently, presumably formed from the chlorophylls and subsequently degraded. The ratio of chlorophyll A/B increased during seed ripening, with fully mature canola seed having a chlorophyll A/B ratio twice that of physiologically mature green seed. The “B” derivatives degraded faster than the “A” derivatives, suggesting enzymatic reactions. The initial steps in the chlorophyll breakdown pathway in canola seed appear to be:      

Trans-22-Dehydrocholesterol and Stigmasta-5,25-dienol in Brassica napus Seed Oil

Three minor sterols found in the sterol fraction separated from the unsaponifiable matter of Brassica napus (Cruciferae) seed oil are identified as trans-22-dehydrocholesterol, stigmasta-5,25-dienol and fucosterol. The former two are regarded indeed as the natural products but fucosterol seems to be the artefact formed by isomerization from 28-isofucosterol, which occurs as one of the abundant sterol constituents of the fraction, during the extensive separation procedures by argentation thin layer chromatography.     

Identification and Fine Mapping of the Candidate Gene Controlling Multi-Inflorescence in Brassica napus

As a desirable agricultural trait, multi-inflorescence (MI) fulfills the requirement of mechanized harvesting and yield increase in rapeseed (Brassica napus L.). However, the genetic mechanism underlying the multi-inflorescence trait remain poorly understood. We previously identified a difference of one pair of dominant genes between the two mapping parental materials. In this study, phenotype and expression analysis indicated that the imbalance of the CLAVATA (CLV)-WUSCHEL (WUS) feedback loop may contribute to the abnormal development of the shoot apical meristem (SAM). BnaMI was fine-mapped to a 55 kb genomic region combining with genotype and phenotype of 5768 BCF₁ individuals using a traditional mapping approach. Through comparative and expression analyses, combined with the annotation in Arabidopsis, five genes in this interval were identified as candidate genes. The present findings may provide assistance in functional analysis of the mechanism associated with multi-inflorescence and yield increase in rapeseed.     

Genetic control of fatty acid biosynthesis in rapeseed (Brassica napus L.)

Isolation of rapeseed plants containing no erucic acid in their seed oil gave simultaneous selection for low eicosenoic acid. Genetic analy-sis of populations segregating for erucic acid content indicated that the synthesis of these fatty acids was controlled, in the developing embryo, by two genes which displayed no domi-nance and acted in an additive manner. As the genetic capacity for erucic acid synthesis de-creased, there was an increase in percentage of oleic acid with no corresponding decrease in total oil content. The percentage of eicosenoic acid re-mained relatively constant with decreasing erucic acid except in the zero erucic acid genotype where only 1% eicosenoic was detected instead of approx 12%. These observations were in-terpreted to mean that eicosenoic and erucic acids were formed by a genetically controlled carbon chain lengthening system operating by the addi-tion of acetate molecules to the carboxyl end of oleic acid. This hypothesis was supported by data obtained from the injection of radioactive sodium acetate into immature rapeseed pods. In the monoene fraction of the oil, eicosenoate had three times the specific activity of oleate and erucate had twice the activity of eicosenoate. On oxidation, the monocarboxylic fragments of these three acids had low and similar specific activities while in the dicarboxylic acids, where chain elongation has presumably taken place, activity increased in the ratio of 1:5:19. AOCS Bond Award, Fall 1963.     

Primary Metabolites and Polyphenols in Rapeseed (Brassica napus L.) Cultivars in China

Defatted meals of 10 rapeseed (Brassica napus L.) varieties were investigated for their total phenolic, phenolic acid (free, esterified, and insoluble-bound forms), and tannin contents. The antioxidant capacities (AC) of methanol extracts from samples were assessed using the 2,2′-diphenyl-1-picrylhydrazyl radical (DPPH•), Folin–Ciocalteu method and ferric reducing antioxidant power (FRAP), and β-carotene–linoleic acid tests. In the fraction of free phenolic acids, sinapic, caffeic, ferulic, syringic, gallic, and p-coumaric acids were identified. In the fraction of esterified phenolic acids, sinapine, sinapoyl glucoside, and disinapoyl gentiobiose were identified. After basic hydrolysis, sinapic, ferulic, cinnamic, and 4-hydroxybenzoic acids were identified, and sinapic acid (SA) constituted 98.3% to 99.6% of the total esterified phenolic acids. Eleven components (sinapic, protocatechuic, p-coumaric, syringic, vanillic, gallic, caffeic, ferulic, salicylic, cinnamic, and 4-hydroxybenzoic acids) in the fraction of insoluble-bound phenolic acids were identified. The AC of the samples correlated with the total phenolic content. Overall, the total phenolics showed a better correlation with AC than the individual phenolic compounds. Moreover, SA, sinapoyl glucoside, and disinapoyl gentiobiose showed a highly significant and strong positive correlation with the AC of rapeseed meals, and the derivatives of cinnamic acid showed a higher correlation with AC than the derivatives of benzoic acid. The change in the canolol content in rapeseeds under microwave irradiation is discussed. The correlation of the canolol formed with SA and its derivatives is discussed.     

An ACP structural switch: conformational differences between the apo and holo forms of the actinorhodin polyketide synthase acyl carrier protein

The actinorhodin (act) synthase acyl carrier protein (ACP) from Streptomyces coelicolor plays a central role in polyketide biosynthesis. Polyketide intermediates are bound to the free sulfhydryl group of a phosphopantetheine arm that is covalently linked to a conserved serine residue in the holo form of the ACP. The solution NMR structures of both the apo and holo forms of the ACP are reported, which represents the first high resolution comparison of these two forms of an ACP. Ensembles of twenty apo and holo structures were calculated and yielded atomic root mean square deviations of well-ordered backbone atoms to the average coordinates of 0.37 and 0.42 A, respectively. Three restraints defining the protein to the phosphopantetheine interface were identified. Comparison of the apo and holo forms revealed previously undetected conformational changes. Helix III moved towards helix II (contraction of the ACP), and Leu43 on helix II subtly switched from being solvent exposed to forming intramolecular interactions with the newly added phosphopantetheine side chain. Tryptophan fluorescence and S. coelicolor fatty acid synthase (FAS) holo-synthase (ACPS) assays indicated that apo-ACP has a twofold higher affinity (K(d) of 1.1 muM) than holo-ACP (K(d) of 2.1 muM) for ACPS. Site-directed mutagenesis of Leu43 and Asp62 revealed that both mutations affect binding, but have differential affects on modification by ACPS. Leu43 mutations in particular strongly modulate binding affinity for ACPS. Comparison of apo- and holo-ACP structures with known models of the Bacillus subtilis FAS ACP-holo-acyl carrier protein synthase (ACPS) complex suggests that conformational modulation of helix II and III between apo- and holo-ACP could play a role in dissociation of the ACP-ACPS complex.     

Knockout of KASIII regulation changes fatty acid composition in canola (Brassica napus)

In contrast to the dominating unsaturated C₁₈ fatty acid, medium‐chain fatty acids (MCFA) are nearly absent in the oil of common canola. Modification of canola oil towards higher contents of C₈ to C₁₄ fatty acids would create new possibilities for oleo‐chemical usages, in both the nutritional and the non‐food sectors. For this purpose, spring oilseed rape (cv. ‘Drakkar’) was genetically modified by introduction of MCFA‐encoding genes from Cuphea species containing approximately 90% MCFA in their seed oil. Two different single constructs involving the 3‐ketoacyl‐acyl carrier protein synthase (KAS)III from C. lanceolata were used, one harbouring the wild‐type gene, ClKASIIIbwt, and the other containing the point‐mutated gene, ClKASIIIbmut, along with two double constructs containing ClKASIIIbmut in combination with a medium‐chain thioesterase gene from C. lanceolata (ClFatB3) or C. hookeriana (ChFatB2). For both single‐gene constructs, a phenotype with an increased content of MCFA was not detected; however, the ClKASIIIbwt transformants produced up to 6.7% palmitic acid (C₁₆). In T2 seeds bearing the ClKASIIIbmut/ClFatB3 double‐gene construct, contents of up to 2.9% capric (C₁₀) and 11.4% palmitic acid were achieved. The best transformant with the gene construct ClKASIIIbmut/ChFatB2 contained 1.4% caprylic acid (C₈) and 7.9% C₁₀, and these results were confirmed in T3 seeds.     

Acyltransferases in subcellular fractions of developing seeds of rape (Brassica napus L.)

Acyltransferase activities responsible for the transfer of oleoyl moieties from oleoyl-CoA to various lipids have been examined in subcellular fractions of developing seeds of rape,Brassica napus L. In the absence of exogenous acyl acceptors, the microsomal and oil body fractions transferred oleoyl moieties mostly to phosphatidylcholines and phosphatidic acids, although there was substantial incorporation of the oleoyl moieties into monoacylglycerols, diacylglycerols and triacylglycerols. The soluble (150,000-g supernatant) fraction incorporated oleoyl moieties mainly into the neutral lipids (monoacylglycerols and diacylglycerols) and also exhibited a relatively high acyl-CoA hydrolase activity. In the presence of the exogenous acyl acceptors, lysophosphatidylcholine and lysophosphatidic acid, both microsomal and oil body fractions transferred most of the oleoyl moieties to phosphatidylcholines and phosphatidic acids, respectively. Other lysophospholipids, such as lysophosphatidylethanolamine and lysophosphatidylonositol, were not very effective as acyl acceptors, nor were glycerol-3-phosphate, monoacylglycerols or diacylglycerols. In contrast, the soluble fraction showed little or no stimulation of acyltransfer in the presence of exogenous lysophospholipids but was able to utilize, to some extent, exogenous monoacylglycerols and diacylglycerols as acyl acceptors.