Effects of antibiotics on secondary metabolism and oxidative stress in oilseed rape seeds

Cruciferae brassica oilseed rape is the third largest oilseed crop in the world and the first in China, as well as a fertilizer-dependent crop. With the increased application of organic fertilizers from livestock manure in agricultural production in recent years, the resulting antibiotic pollution and its ecological health effects have attracted widespread attention. In this study, typical tetracycline and sulfonamide antibiotics tetracycline (TC) and sulfamethoxazole (SMZ) were used to investigate the effects of antibiotics on rapeseed quality and oxidative stress at the level of secondary metabolism on the basis of examining the effects of the two drugs on the growth of soil-cultivated rapeseed seedlings. The results showed that both plant height and biomass of rapeseed seedlings were significantly suppressed and ROS were significantly induced in rapeseed by exposure to high concentrations (2.5 mg/kg) of TC and SMZ. Carotenoids, tocopherols, and SOD enzymes were involved in the oxidative stress response to scavenge free radicals in rapeseed, but phenolic acids and flavonoids contents were decreased, which reduced the quality of the seeds to some extent.

Predicting the allergenic risk of Phosphite-NAD+-Oxidoreductase and purple acid phosphatase 17 proteins in genetically modified canola using bioinformatic approaches

Recent advancements in the generation of high-throughput multi-omics data have provided a vast array of candidate genes for the genetic engineering of plants. However, as part of their safety assessment, newly expressed proteins in genetically modified crops must be evaluated for potential cross-reactivity with known allergens. In this study, we developed transgenic canola plants expressing the Arabidopsis thaliana PAP17 gene and a novel selectable marker composed of the ptxD gene from Pseudomonas stutzeri. To evaluate the potential allergenic cross-reactivity of the AtPAP17 and PTXD proteins expressed in transgenic canola, we applied a comprehensive approach utilizing sequence-based, motif-based, and 3D structure-based analyses. Our results demonstrate that the risk of conferring cross-reactivity with known allergens is negligible, indicating that the expression of these proteins in transgenic canola poses a low allergenic risk.

Effect of exogenous taurine on growth, oxidative defense, and nickel (Ni) uptake in canola (Brassica napus L.) under Ni stress

Nickel (Ni) contamination and its associated hazardous effects on human health and plant growth are ironclad. However, the potential remedial effects of taurine (TAU) on Ni-induced stress in plants remain obscure. Therefore, the present study was undertaken to examine the effect of TAU seed priming (100 and 150 mg L‒1) as an alleviative strategy to circumvent the phytotoxic effects of Ni (150 mg kg‒1) on two canola cultivars (Ni-tolerant cv. Shiralee and Ni-sensitive cv. Dunkeld). Our results manifested an apparent decline in growth, biomass, photosynthetic pigments, leaf relative water content, DPPH free radical scavenging activity, total soluble proteins, nitrate reductase activity, and nutrient acquisition (N, P, K, Ca) under Ni toxicity. Further, Ni toxicity led to a substantial increase in oxidative stress reflected as higher levels of superoxide radicals (O2•‒) and hydrogen peroxide (H2O2) alongside increased relative membrane permeability, lipoxygenase (LOX) activity, and Ni accumulation in leaves and roots. However, TAU protected canola plants from Ni-induced oxidative damage through the amplification of hydrogen sulfide (H2S) production that intensified the antioxidant system to avert O2•‒, H2O2, and malondialdehyde (MDA) production. Further, TAU-mediated increase in H2S levels maintained membrane integrity that might have improved ionomics and bettered plant growth under Ni toxicity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-023-01359-9.

Ruminal responses, digestibility, and blood parameters of beef cattle fed diets with different oilseeds

It aimed to evaluate the effects of different whole oilseeds in lipid-rich diets on nutrient intake, apparent digestibility, ingestive behavior, and ruminal and blood parameters of steers. A control diet (without oilseed) and four diets containing whole oilseeds (cotton, canola, sunflower, and soybean) were tested. All diets used the whole-plant corn silage at 400 g/kg as roughage. Five diets, being a control diet (without oilseed) and four diets containing whole oilseeds (cotton, canola, sunflower, and soybean), were tested. All diets used the whole-plant corn silage at 400 g/kg as roughage. Five rumen fistulated crossbreed steers, in a 5 × 5 Latin square design were distributed using five periods of 21 days. The steers fed cottonseed and canola diets had lower dry matter intakes (6.6 kg/day). Steers showed higher averages of time in rumination for treatments with sunflower, soybean, and cottonseed (406, 362, and 361 min/day, respectively). There was no treatment effect for the ruminal pH and ammonia (NH₃) variables. There was an effect of the treatment on the volatile fatty acid concentrations. The animals that received soybean showed a higher plasma urea concentration (50.7 mg/dL). Animals fed the control diet showed lower serum cholesterol levels (111.8 mg/dL) than those fed diets containing whole cottonseed, canola, sunflower, and soybean (152.7, 137.1, 146.9, and 138.2 mg/dL, respectively). We recommended using whole soybean or sunflower seeds to formulate lipid-rich diets with 70 g/kg of ether extract for crossbreed steers in the feedlot.

Plant growth promoting bacteria (PGPR) induce antioxidant tolerance against salinity stress through biochemical and physiological mechanisms

Salinity is one of the most severe abiotic stress in the world. Also, the irrigated lands have been treated with second salinity. Canola is one of the most important industrial crops for oil production all over the world which is affected by salinity. Salt stress causes imbalanced ion hemostasis (Na⁺ and K⁺) and interrupted mineral absorption in canola. Also, salinity stress leads to oxidative stress (production and accumulation of reactive oxygen species (ROS). Accumulation of ROS is extremely dangerous and lethal for plants. As a consequence, canola production is reduced under salinity stress. So, a suitable approach should be found to deal with salinity stress and prevent the loss of production oilseed. Plant growth-promoting rhizobacteria (PGPR) can colonize on the plant root surface and alleviate the salt stress effect by providing minerals like nitrogen, phosphate, and potassium. Also, they alleviate salt stress by phytohormones like auxin (IAA), cytokinin (CK), and abscisic acid (ABA). This study focus on physiological parameters like leaf area (LA), root length (RL), shoot length (SL), chlorophyll fluorescence indexes (F_v/F_m and F_v/F₀), relative water content (RWC), electrolyte leakage index (ELI), photosynthesis pigments (chlorophyll a, b, and carotenoids), Na⁺, and K⁺; and biochemical parameters like malondialdehyde (MDA) content, hydrogen peroxide content (H₂O₂), total protein content, proline, antioxidant capacity, and antioxidant enzyme activities in canola through the inoculation with Enterobacter sp. S16-3 and Pseudomonas sp. C16-2O. This study showed that LA, RL, SL, chlorophyll fluorescence indexes, RWC were significantly increased and ELI was significantly decreased in bacteria inoculated treatments. Also, MDA, H₂O₂ were decreased, and antioxidant capacity, proline, and antioxidant enzymes were increased due to inoculation with these bacteria. Besides, the amount of K⁺ as an index of salinity tolerance significantly increased, and leaf Na⁺ content was significantly decreased.

Effects of diesel-engine exhaust emissions on seed germination and seedling growth of Brassicaceae family using digital image analysis

This paper describes a multi-phase investigation into the direct effect of diesel exhaust emission on seed germination traits and biochemical changes responsible for observed effects in seeds belongs to the Brassica family. Diesel exhaust emissions were collected in germination boxes and seeds were exposed to diesel exhaust pollutants for durations of 30 to 120 min with 30 min intervals. Observed effects include seed germination inhibition, changes in seeds' antioxidants activity, and protein content. The lowest seed germination of canola (71 %) and arugula (84 %) was observed when seeds were exposed to 120 min of diesel exhaust pollution. Seed exposure to diesel exhaust emission for 60 min, caused a 23 % and 8 % decline of germination index of canola and arugula, respectively. The maximum seed soluble protein for canola (3.72 mg/g FW) was observed in seeds exposed to 120 min diesel exhaust pollution declined to 1.65 mg/g FW, and 0.60 mg/g FW after 60 and 30 min exposure to diesel exhaust, respectively. The maximum protein content of arugula seeds (0.95 mg/g FW) was observed in the control treatment and it was reduced to 0.72 mg/g FW and 0.53 mg/g FW after 60 and 90 min exposure to diesel exhaust pollution. Catalase activity was significantly reduced as canola seed exposure to diesel exhausted was increased while there were no statistically significant changes for catalase activity of arugula seeds. All evidence suggested that time of exposure was the key phytotoxic component of exhaust emissions, and highlights the potential for detrimental effects of vehicle emissions on agro-ecosystems.

Potential risks from the accumulation of heavy metals in canola plants

Concentrations of heavy metals in agricultural land near highways are a major concern for humans. This study was conducted to investigate the contamination level of heavy metals in soil, canola crop, and the potential health risk for honeybee and human. The average concentrations (mg/kg) of Co (15.94), Cr (169.66), Ni (55.39), Mn (765.34) Hg (2.99), and Cu (51.31) were elevated beyond their background reference values in world soil average, while Pb (9.45) was below to their respective background levels. This was confirmed by contamination factor (CF) and ecological risk factors (Er). Heavy metal concentrations in different parts of canola decreased in the following order: Fe> Mn > Cr > Pb > Co > Cu > Ni > Hg. Honey transfer factor (TF_H) of heavy metals was less than unity except Ni and Hg. Human health (non-carcinogenic) risk assessment of heavy metals in the soil through potential exposure pathway (ingestion) recorded a dramatically increased risk for children (hazard index, HI=2.44). Hazard quotient via honey (HQ_H) consumption value of heavy metals were within the safe limits (HQ< 1). Probably, honeybees have a strong ability to transfer Co, Pb, Hg, and Mn (HQ> 1) from the canola to their hives during collecting pollen and nectar. HQ in honeybee workers from the consumption of honey can be used to derive HQ in humans using the hazard factor (HF). HF is 1481.482 (Pb), 2356.902 (Ni), and 3888.889 (Cr), respectively, for adult human (70kg) and 317.460 (Pb), 504.377(Ni), and 832.22 (Cr) for children (15kg).

Growth attributes, biochemical modulations, antioxidant enzymatic metabolism and yield in Brassica napus varieties for salinity tolerance

Improvement in salinity tolerance of plants is of immense significance as salt stress particularly threatens the productivity of agricultural crops. This study was designed to assess the tolerance level of six Brassica napus varieties (Super, Sandal, Faisal, CON-111, AC Excel and Punjab) under different levels of salinity (0, 50, 100, 150 & 200 mM) with three replications under CRD. Salt induced osmotic stress curtailed the plant growth attributes, photosynthetic pigments and disturbed ionic homeostasis (K⁺, Na⁺, Ca^2+, Cl^-) but least disturbance as compared to control was found in Super and Sandal cultivars. Punjab canola and AC Excel canola cultivars were least tolerant to salinity because these displayed greater decline in all growth and biochemical attributes. Plants subjected to NaCl induced stress exhibited considerable decline in all attributes under study with proline as exception. Antioxidants (CAT, SOD & POD) showed an obvious change in Canola plants under stress, but greatest decline was displayed at 200 mM NaCl level in all six cultivars. Over all these attributes presented a comparatively stable trend in super and sandal cultivars. This shows presence of physiological resilience and metabolic capacity in these two cultivars to tackle salinity. Similarly, all yield attributes displayed adverse behavior under 150 mM & 200 mM salinity stress. Our results demonstrated that Super and Sandal cultivars of Brassica napus exhibit good performance in salinity tolerance and can be good option for cultivation in salt affected areas.

Influence of foliar glutathione and putrescine on metabolism and mineral status of genetically diverse rapeseed cultivars under hexavalent chromium stress

We studied the physio-biochemical involvement of exogenous signaling compounds, glutathione and putrescine (alone and in combination), on three contrasting genotypes (cvs. Shiralee, Rainbow, and Dunkled) of canola (Brassica napus L.) of plants exposed to chromium stress. Seeds were germinated in Cr-contaminated soil (0 and 50 μg/g Cr⁶⁺), and both signaling compounds were applied as a foliar spray to 20-day-old plants. Changes in root, stem, and leaf nitro-oxidative metabolism, endogenous GSH level, secondary metabolites, and mineral nutrients were investigated from 60-day-old plants. Exposure to Cr⁶⁺ increased stem GSH and NO concentrations in all cultivars. Maximum root Cr⁶⁺ bioaccumulation was recorded in cv. Rainbow and the least in cv. Shiralee. Also, Cr⁶⁺ stress decreased number and weight of seeds and pod length. Disturbances in root and shoot mineral profile were evident; however, its magnitude varied in all cultivars. The exogenous GSH improved root and shoot P, Fe, S, and Zn concentrations; however, the effect was cultivar specific. Leaf endogenous GSH was increased by exogenous GSH while NO levels remained unaffected. The GSH application also promoted shoot Cr⁶⁺ bioaccumulation while PUT application caused a recovery in seed number and seed weight. Both PUT and GSH differentially affected tissue-specific secondary metabolite profile. Overall, the exogenous GSH was much more effective in alleviating the Cr⁺⁶ toxicity in canola.

Individual Rather Than Simultaneous Priming with Glutathione and Putrescine Reduces Chromium Cr6+ Toxicity in Contrasting Canola (Brassica napus L.) Cultivars

The chromium (Cr⁶⁺) toxicity mechanisms have not been fully revealed yet in plants mainly due to its complex electronic chemistry. Both putrescine (PUT) and glutathione (GSH) are reported to be involved in plethora of plant cellular processes. Therefore, we hypothesized that exogenous individual or co-application of PUT and GSH could alleviate the Cr⁶⁺ stress in genetically diverse canola cultivars. The seed priming with GSH (0.1 mM) alleviated inhibitory effects of Cr⁶⁺ on root growth, and thus plants raised from GSH-treated seed had higher leaf chlorophyll a contents (78, 69 and 82%, in Shiralee, Rainbow and Dunkled cultivar, respectively), carotenoids contents, stem phenolics, root GSH, leaf and root NO concentration. The foliar treatment with PUT caused 37 and 11.9% decrease in the accumulation of Cr in shoot of Shiralee and Dunkled, respectively. Overall, the results suggested that seed priming with GSH regulated leaf photosynthetic pigments to cope with Cr⁶⁺ shock at early growth stage whereas foliar treatment with PUT decreased Cr transport to the shoot, and thus increased tolerance at later growth stage irrespective of cultivars.

Doubled Haploid Production in High- and Low-Response Genotypes of Rapeseed (Brassica napus) Through Isolated Microspore Culture

Rapeseed (Brassica napus) is one of the most important oilseed crops worldwide. It is also a model system to study the process of microspore embryogenesis, due to the high response of some B. napus lines, and to the refinements of the protocols. This chapter presents a protocol for the induction of haploid and DH embryos in B. napus through isolated microspore culture in two specific backgrounds widely used in DH research, the high response DH4079 line and the low response DH12075 line. We also present methods to identify the best phenological window to identify buds with microspores/pollen at the right developmental stage to induce this process. Methods to determine microspore/pollen viability and to check the ploidy by flow cytometry are also described.

A holistic decision-making approach for identifying influential parameters affecting sustainable production process of canola bast fibres and predicting end-use textile choice using principal component analysis (PCA)

Recent research has discovered and validated that canola fibre polymer has a lower density than major industrial fibres like cotton, jute, hemp, or flax. A few studies have identified key backgrounds that relate to canola fibre polymer production parameters; however, none have modelled an analytical hierarchy process to identify the influential parameters while producing the canola fibre polymers. The current study used Plackett-Burman design analysis to optimize the fibre polymer yield (%) during retting Statistical tools including Fisher's LSD, ANOVA, Pearson's correlation coefficient, and principal component analysis (PCA) were applied for a comparative analysis among four different canola cultivars (HYHEAR 1, Topas, 5440, 45H29). Physical testing and non-parametric statistical analysis tools like Chi-square (X²) test were used to investigate the effect of cultivar on the physique of the stems--the source of biomass. This holistic approach was taken to correlate key factors for the sustainable manufacturing of canola fibre polymers. Such knowledge will lay an effective foundation for future material-science research works, consumer wearable manufacturing industries, and engineering design for composite or nonwoven fabrication using this lightweight natural fibre polymer.

Enhancing Coverage of Phosphatidylinositol Species in Canola Through Specialised Liquid Chromatography-Mass Spectrometry Buffer Conditions

Phosphatidylinositols (PIs) constitute a minor class of phospholipid with wide-spread influence throughout various cellular functions. Monitoring the distribution of these lipids can therefore provide insight as to the state of cellular processes or reveal the development of various pathologies. The speciation of these compounds is often performed either as part of a comprehensive characterisation of lipids, or specifically targeted using the same methods, however, such methods were intended to maximise coverage of lipid classes rather than provide an in-depth analysis of any single class. In the particular case of PIs, the majority of reported molecular diversity is limited to a small proportion of the already minor class, as such the cursory glance enabled by such methods is insufficient. Therefore, this work compared the suitability of both established and novel LC-MS buffers with the aim of maximising the ionisation efficiency of PIs, in an attempt to enhance coverage of the class. Through experimentation, it was determined that a 0.25 mM ammonium fluoride buffer provided up to a 6-fold increase in signal intensity, and on average a 38-fold increase in the signal-to-noise ratio. Using these new conditions, 14 PI species, and 12 PI candidates were identified within a dilute lipid extract sourced from canola seed, compared to 0 species identified using the generalised method. As a result, it is suggested that this procedure has yielded the highest number of PI species identifications for a sample of this concentration. Methods which therefore intend to characterise PI species in dilute quantities, such as those extracted from mammalian cells, are henceforth provided with the means to conduct more comprehensive characterisations.

Individual and interactive effects of temperature and light intensity on canola growth, physiological characteristics and methane emissions

Earlier studies have shown that plants produce methane (CH₄) under aerobic conditions, and that this emission is not microbial in nature. However, the precursors of aerobic CH₄ remain under debate, and the combined effects of environmental factors on plant-derived CH₄ requires further attention. The objective of this study was to determine the interactive effects of temperature and light intensity on CH₄ and other relevant plant parameters in canola (Brassica napus L.). Plants were grown under two temperature regimes (22/18 °C and 28/24 °C, 16 h light/8 h dark) and two light intensities (300 and 600 μmol photons m^-2 s^-1) for 21 days after one week of growth under 22/18 °C (16 h light/8 h dark). In this study, higher temperature had little effects on CH₄ emissions from plants, indicating the mitigating effects of higher light intensity. Higher light intensity, however, significantly decreased CH₄, which was inversely related to plant dry mass. Higher light intensity decreased stem height, leaf area ratio, chlorophyll, nitrogen balance index, leaf moisture, methionine (Met) and ethylene (C₂H₄), but increased specific leaf mass, photochemical quenching, flavonoids, epicuticular wax, lysine and tyrosine. The results revealed that increased CH₄ emissions from plants could be related to changes in plant physiological activities, which portrayed themselves in increased C₂H₄ evolution, and methylated amino acids, such as Met. We conclude that higher light intensity reduces Met and, in turn, CH₄ and C₂H₄ emissions, but lower light intensity enhances CH₄ formation through cleavage of methyl group of amino acids by reactive oxygen species, as previously suggested.

Biosynthesis of polyhydroxyalkanoates from vegetable oil under the co-expression of fadE and phaJ genes in Cupriavidus necator

The acyl-CoA dehydrogenase (FadE) and (R)-specific enoyl-CoA hydratase (PhaJ) are functionally related to the degradation of fatty acids and the synthesis of polyhydroxyalkanoates (PHAs). To verify this, a recombinant Cupriavidus necator H16 harboring the plasmid -pMPJAS03- with fadE from Escherichia coli strain K12 and phaJ1 from Pseudomonas putida strain KT2440 under the arabinose promoter (araC-P_BAD) was constructed. The impact of co-expressing fadE and phaJ genes on C. necator H16/pMPJAS03 maintaining the wild-type synthase on short-chain-length/medium-chain-length PHA formation from canola or avocado oil at different arabinose concentrations was investigated. The functional activity of fadE_E.c led to obtaining higher biomass and PHA concentrations compared to the cultures without expressing the gene. While high transcriptional levels of phaJ1_P.p, at 0.1% of arabinose, aid the wild-type synthase to polymerize larger-side chain monomers, such as 3-Hydroxyoctanoate (3HO) and 3-Hydroxydecanoate (3HD). The presence of even small amounts of 3HO and 3HD in the co-polymers significantly depresses the melting temperature of the polymers, compared to those composed of pure 3-hydroxybutyrate (3HB). Our data presents supporting evidence that the synthesis of larger-side chain monomers by the recombinant strain relies not only upon the affinity of the wild-type synthase but also on the functionality of the intermediate supplying enzymes.

Canola oilseed- and Escherichia coli- derived hepatitis C virus (HCV) core proteins adjuvanted with oil bodies, induced robust Th1-oriented immune responses in immunized mice

Induction of broad Th1 cellular immune responses and cytokines is crucial characteristics for vaccines against intracellular infections such as hepatitis C virus (HCV). Plants (especially oilseed tissues) and plant-immunomodulators (like oil bodies) offer cost-effective and scalable possibilities for the production of immunologically relevant and safe vaccine antigens and adjuvants, respectively. Herein, we provide data of the murine immunization by transgenic canola oilseed-derived HCV core protein (HCVcp) soluble extract (TSE) and Escherichia coli- derived rHCVcp in combination with Canola oil bodies (oil) compared to that of the Freund's (FA) adjuvant. Mice immunized by TSE+ oil developed both strong humeral (IgG) and Th1-biased cellular responses, manifested by high levels of IFN-γ and lower IgG1/IgG2a ratio and IL-4 secretion. Results of the intracellular cytokine staining indicated that TSE+ oil immunization in mice triggered both CD4⁺ and CD8⁺ T cells to release IFN-γ, while CD4⁺ cells were mostly triggered when FA was used. Analyses by qRT-PCR indicated that a combination of rHCVcp/TSE with oil body induced high levels of IL-10 cytokines compared to that of the FA adjuvant. These characteristics are important properties for the design of an HCV vaccine candidate and indicate the potential of Canola-derived antigen and oil bodies in addressing these concerns.

An intensive multilocation temporal dataset of fungal and bacterial communities in the root and rhizosphere of Brassica napus

The plant microbiome has been recently recognized as a plant phenotype to help in the food security of the future population. However, global plant microbiome datasets are insufficient to be used effectively for breeding this new generation of crop plants. We surveyed the diversity and temporal composition of bacterial and fungal communities in the root and rhizosphere of Brassica napus, the world's second largest oilseed crop, weekly in eight diverse lines at one site and every three weeks in sixteen lines, at three sites in 2016 and 2017 in the Canadian Prairies. We sequenced the bacterial 16S ribosomal RNA gene generating a total of 127.7 million reads and the fungal internal transcribed spacer (ITS) region generating 113.4 million reads. 14,944 unique fungal amplicon sequence variants (ASV) were detected, with an average of 43 ASVs per root and 105 ASVs per rhizosphere sample. We detected 10,882 unique bacterial ASVs with an average of 249 ASVs per sample. Temporal, site-to-site, and line-driven variability were key determinants of microbial community structure. This dataset is a valuable resource to systematically extract information on the belowground microbiome of diverse B. napus lines in different environments, at different times in the growing season, in order to adapt effective varieties for sustainable crop production systems.

Melatonin induced changes in photosynthetic efficiency as probed by OJIP associated with improved chromium stress tolerance in canola (Brassica napus L.)

Chromium toxicity is considered as a major problem for agricultural soil that reduced crop productivity by affecting photosynthetic tissues. Exogenous application of melatonin can alleviate the adverse effects of chromium toxicity on plant growth. However, little is known about its effect on thylakoidal protein complexes responsible for conversion of solar energy to biochemical energy. Chlorophyll fluorescence a transients considered one of the best non-invasive and rapid method for the evaluation of photosynthetic (Photosystem II) efficiency of plants and plant health under environmental stress conditions. In the present study, three-week old plants of two canola cultivars AC-Excel and DGL were applied to melatonin (0, 1, 5, 10 μM) when grown under chromium stress (0, 50 and 100 μM) for further two weeks. Chromium stress reduced the growth (fresh and dry weights of shoots and roots) of both canola cultivars and exogenous application of 5 and 10 μM melatonin improved the growth of canola at 50 or 100 μM chromium stress. This improvement was greater in cv DGL than in AC-Excel. Increasing chromium decreased the photosynthetic pigments (chlorophyll a and chlorophyll b). However, 5 and 10 μM melatonin application improved chlorophyll a at 50 μM chromium stress. Structural stability and efficiency of photosystem II (PSII) measured as performance index (PI_ABS) and ratios of fluorescence (Fv/Fm, Fv/Fo) Fv decreased due to chromium stress. JIP-test parameters showed that chromium stress increased the absorption and trapping fluxes with decrease in electron transport fluxes which caused the damage to reaction centers (RC), detachment of oxygen evolving complex (OEC) from RC or inefficiency of electron transfer from OEC to RC. Such adverse effects were greater in cv AC-Excel. However exogenous application of melatonin improved PI_ABS, electron transport per reaction center (ET/RC), reduced variable fluorescence at J step (V_J) reflecting melatonin protected PSII from chromium stress induced damage by protecting OEC. Thus, OJIP fluorescence transients are quite helpful for understanding the intersystem electron transport beyond photosystem II in canola cultivars due to melatonin application under chromium stress.

Findings

Exogenous application of melatonin alleviated toxic effects of chromium on plant growth of canola by modulating photosynthesis, enhanced photosystem II efficiency and regulation of electron transport flux to protect photo-inhibition of PSII from oxidative damage.

Genome-wide analysis of AP2/ERF transcription factors family in Brassica napus

The AP2/ERF transcription factor family plays an important role in different biological processes such as growth, development and response to abiotic and biotic stresses in plants. The genome-wide analysis identified 531 AP2/ERF genes in Brassica napus (oilseed rape or canola) that ranged from 333 to 6440 bp in genomic and 273-2493 bp in coding DNA sequence length. We classified BnAP2/ERF proteins into five subfamilies including AP2 (58 genes), ERF (250 genes), DREB/CBF (194 genes), RAV (26 genes), and Soloist (3 genes). Furthermore, AP2/ERF proteins were subdivided into 15 groups according to the AP2/ERF classification in Arabidopsis. The number of exons in BnAP2/ERF genes was from one to eleven and most of these genes in the same subfamily had the same exon-intron pattern. The results also indicated that the composition of conserved motifs in most proteins in each group was similar. The intron-exon patterns and the composition of conserved motifs validated the BnAP2/ERF transcription factors phylogenetic classification. Based on the results of genome distribution, BnAP2/ERF genes were located unevenly on the 19 B. napus chromosomes. The results indicated that gene duplication may play an important role in genome expansion of B. napus. Furthermore, genome evolution of B. napus using orthologous and paralogous identification was studied. We found 278, 380 and 366 orthologous gene pairs between B. napus with A. thaliana, B. rapa and B. oleracea, respectively. The results of this study will be useful in investigation of functional role and molecular mechanisms of BnAP2/ERF transcription factors genes in response to different stresses.

Canola produced under boreal climatic conditions in Newfoundland and Labrador have a unique lipid composition and expeller press extraction retained the composition for commercial use

The average fatty acid (FA) composition of canola oil is made up of 62% oleic acid (C18:1n9), 19% linoleic acid (C18:2n6), 9% linolenic acid (C18:3n3) and 7% saturated FA (SFA). We investigated whether boreal climate (7.5-17.2 °C) favorably altered the FA composition of canola. Results indicate that canola cultivated in boreal climatic conditions had approximately twice the levels of omega-3 FA (17-20%) compared to canola from other growing areas (9%). The presence of monoacetyldiacylglycerol (MAcDG), a unique class of triglyceride, is reported for the first time in canola cultivated in a boreal climate, and has the potential to reduce the risk of obesity and other health related diseases. We further demonstrated that a non-solvent based extraction method retained the novel lipid composition without reducing the quality of oil being produced. Our results contribute significantly to the understanding of lipid accumulation in the world's second most important oil crop when cultivated in a boreal or northern climate.

An intensive multilocation temporal dataset of fungal communities in the root and rhizosphere of Brassica napus

The plant microbiome has been recently recognized as a plant phenotype to help in the food security of the future population. However, global plant microbiome datasets are insufficient to be used effectively for breeding this new generation of crop plants. We surveyed the diversity and temporal composition of fungal communities in the root and rhizosphere of Brassica napus, the world's second largest oilseed crop, weekly in eight diverse lines at one site and every three weeks in sixteen lines, at three sites in 2016 and 2017 in the Canadian Prairies. 14,944 unique amplicon sequence variants (ASV) were detected based on the internal transcribed spacer region, with an average of 43 ASVs per root and 105 ASVs per rhizosphere sample. Temporal, site-to-site, and line-driven variability were key determinants of fungal community structure. This dataset is a valuable resource to systematically extract information on the belowground microbiome of diverse B. napus lines in different environments, at different times in the growing season, in order to adapt effective varieties for sustainable crop production systems.

Detecting flowering phenology in oil seed rape parcels with Sentinel-1 and -2 time series

A novel methodology is proposed to robustly map oil seed rape (OSR) flowering phenology from time series generated from the Copernicus Sentinel-1 (S1) and Sentinel-2 (S2) sensors. The time series are averaged at parcel level, initially for a set of 229 reference parcels for which multiple phenological observations on OSR flowering have been collected from April 21 to May 19, 2018. The set of OSR parcels is extended to a regional sample of 32,355 OSR parcels derived from a regional S2 classification. The study area comprises the northern Brandenburg and Mecklenburg-Vorpommern (N) and the southern Bavaria (S) regions in Germany. A method was developed to automatically compute peak flowering at parcel level from the S2 time signature of the Normalized Difference Yellow Index (NDYI) and from the local minimum in S1 VV polarized backscattering coefficients. Peak flowering was determined at a temporal accuracy of 1 to 4 days. A systematic flowering delay of 1 day was observed in the S1 detection compared to S2. Peak flowering differed by 12 days between the N and S. Considerable local variation was observed in the N-S parcel-level flowering gradient. Additional in-situ phenology observations at 70 Deutscher Wetterdienst (DWD) stations confirm the spatial and temporal consistency between S1 and S2 signatures and flowering phenology across both regions. Conditions during flowering strongly determine OSR yield, therefore, the capacity to continuously characterize spatially the timing of key flowering dates across large areas is key. To illustrate this, expected flowering dates were simulated assuming a single OSR variety with a 425 growing degree days (GDD) requirement to reach flowering. This GDD requirement was calculated based on parcel-level peak flowering dates and temperatures accumulated from 25-km gridded meteorological data. The correlation between simulated and S2 observed peak flowering dates still equaled 0.84 and 0.54 for the N and S respectively. These Sentinel-based parcel-level flowering parameters can be combined with weather data to support in-season predictions of OSR yield, area, and production. Our approach identified the unique temporal signatures of S1 and S2 associated with OSR flowering and can now be applied to monitor OSR phenology for parcels across the globe.

LmCBP1, a secreted chitin-binding protein, is required for the pathogenicity of Leptosphaeria maculans on Brassica napus

Leptosphaeria maculans is the causal agent of blackleg disease on Brassica napus. Determining the underlying functions of genes required for pathogenesis is essential for understanding the infection process. A chitin-binding protein (LmCBP1) was discovered as a pathogenicity factor for the infection of B. napus by L. maculans through gene knockout using the CRISPR-Cas9 system. Chitin-binding activity was demonstrated through a chitin-protein binding assay. A secreted signal peptide was detected using a yeast secreted-signal peptide trap assay. An increased expression level during the infection stage was also observed, suggesting that LmCBP1 is a secreted protein. The knockout mutants showed decreased infection on B. napus, with reduced pathogenicity on ten cultivars with/without diverse R genes. The mutants were more sensitive to H₂O₂ compared to wild type L. maculans isolate JN3. This study provides evidence of the virulence of a novel chitin-binding protein LmCBP1 on B. napus through mutants created via the CRISPR-Cas9 system.

GWAS hints at pleiotropic roles for FLOWERING LOCUS T in flowering time and yield-related traits in canola

Background

Transition to flowering at the right time is critical for local adaptation and to maximize grain yield in crops. Canola is an important oilseed crop with extensive variation in flowering time among varieties. However, our understanding of underlying genes and their role in canola productivity is limited.

Results

We report our analyses of a diverse GWAS panel (300–368 accessions) of canola and identify SNPs that are significantly associated with variation in flowering time and response to photoperiod across multiple locations. We show that several of these associations map in the vicinity of FLOWERING LOCUS T (FT) paralogs and its known transcriptional regulators. Complementary QTL and eQTL mapping studies, conducted in an Australian doubled haploid population, also detected consistent genomic regions close to the FT paralogs associated with flowering time and yield-related traits. FT sequences vary between accessions. Expression levels of FT in plants grown in field (or under controlled environment cabinets) correlated with flowering time. We show that markers linked to the FT paralogs display association with variation in multiple traits including flowering time, plant emergence, shoot biomass and grain yield.

Conclusions

Our findings suggest that FT paralogs not only control flowering time but also modulate yield-related productivity traits in canola.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5964-y) contains supplementary material, which is available to authorized users.

Effect of canola proteins on rice flour bread and mathematical modelling of the baking process

The aim of the present work was to study the technological impact of incorporating canola protein concentrate (extract) into gluten-free bread formulation made of white rice flour. The main properties of the obtained dough and bread were compared to two control formulations made of 100% wheat flour and 100% rice flour. The canola protein concentrate was added at 3, 6 and 9% supplementation level of the rice flour. The bread making process was conducted by approved technology and the obtained results showed that addition of canola protein concentrate to rice flour significantly improved the overall quality of the resulted bread even if its mass volume (1.777 mL/g) and honeycomb structure were of lower quality compared to those of control bread which was made of 100% wheat flour (2.518 mL/g). However, the mass volume of rice bread supplemented with canola protein concentrate was significantly higher than that of bread made of 100% rice flour (1.417 mL/g. In summary, this project demonstrated the positive impact of canola proteins incorporation into white rice flour-based gluten-free bread. These results contribute to the progress of current research focusing on substituting gluten by other proteins having good techno-functional properties. Moreover, a mathematical model was used to explain the impact of the added canola protein concentrate on the intensity of the reactions involved in the dough matrix during oven baking. The obtained model clearly highlighted the significant effect of both the baking time and temperature.

Genome-wide haplotype analysis improves trait predictions in Brassica napus hybrids

Combining ability is crucial for parent selection in crop hybrid breeding. Many studies have attempted to provide reliable and quick methods to identify genome regions in parental lines correlating with improved hybrid performance. The local haplotype patterns surrounding densely spaced DNA markers include a large amount of genetic information, and analysis of the relationships between haplotypes and hybrid performance can provide insight into the underlying genome regions which might contribute to enhancing combining ability. Here, we generated 24,403 single-copy, genome-wide SNP loci and calculated the general combining ability (GCA) of 950 hybrids from a diverse panel of 475 pollinators of spring-type canola inbred lines crossed with two testers for days to flowering (DTF) and seed glucosinolate content (GSL). We performed a genome-wide analysis of the haplotypes and detected eight and seven haplotype regions that were significantly associated with the GCA values for DTF and seed GSL, respectively. Additionally, two haplotype blocks containing orthologs of flowering time genes FLOWERING LOCUS T (FT) and FLOWERING LOCUS C (FLC) on chromosome A02 showed additive epistatic interactions influencing flowering time. Moreover, two homoeologous haplotype regions on chromosomes A02 and C02 corresponded to major quantitative trait loci (QTL) for GSL which showed additive effects related to reduction of seed GSL in F1 hybrids. Our study showed that haplotype analysis has the potential to substantially improve the efficiency of hybrid breeding programs.

Proteomics reveals the in vitro protein digestibility of seven transmembrane enzymes from the docosahexaenoic acid biosynthesis pathway

The measurement of protein digestibility is one of the key steps in determining the safety of a genetically modified crop that has been traditionally accomplished using antibodies. Membrane proteins are often extremely difficult to express with replicated authentic tertiary structure in heterologous systems. As a result raising antibodies for use in safety assessment may not be feasible. In this study, LC-MS based proteomics was used to characterise seven transmembrane enzymes from the docosahexaenoic acid biosynthetic pathway that had been introduced into canola. The application of a two-stage digestion strategy involving simulated gastric fluid followed by trypsin enabled the measurement of protein digestibility in vitro. Tryptic peptide markers that spanned the length of each desaturase protein were monitored and showed that these proteins were readily degraded (>95% within 5 min) and highlighted regions of the elongase enzymes that showed limited resistance to simulated gastric digestion. Traditional gel-based and Western blotting analysis of ω3-desaturase and Δ6-elongase revealed rapid hydrolysis of the intact proteins within seconds and no fragments (>3 kDa) remained after 60 min, complementing the novel approach described herein. The LC-MS approach was sensitive, selective and did not require the use of purified proteins.

Chemical composition, in vitro gas production, methane production and fatty acid profile of canola silage (Brassica napus) with four levels of molasses

The objective of this study was to investigate the effect of four levels of molasses on chemical composition, in vitro digestibility, methane production and fatty acid profile of canola silages. A canola (Brassica napus var. Monty) crop was established in a small-scale agricultural farm and harvested 148 days after sowing. Four levels of molasses were tested with respect to the fresh weight (1.5 kg); these were 1% (CS-1), 2% (CS-2), 3% (CS-3) and 4% (CS-4) molasses, and 0% molasses (CS-0) was included as a control. A total of 45 microsilages were prepared using PVC pipes (4 in. of diameter × 20 cm of length), and the forage was compressed using a manual press. The effects of control and treatments were tested using the general linear model Y = μ + T_i + E_ij. The linolenic acid (C18:3n3), palmitic acid (C16:0) and linoleic acid methyl ester (C18:2n6c) accounted for 30%, 21% and 10.5% of total fatty acids, respectively; the fermentation parameters and in vitro methane production were not affected (P > 0.05) by treatments; in vitro digestibility decreased significantly (P < 0.05) as the level of molasses increased. It was concluded that CS-4 improved the DM content by 9% and showed high content of linolenic acid methyl ester. The gross energy of canola silages could favour the oleic acid methyl ester.

Quantitation of seven transmembrane proteins from the DHA biosynthesis pathway in genetically engineered canola by targeted mass spectrometry

Examining tissue-specific expression and the measurement of protein abundance are important steps when assessing the performance of genetically engineered crops. Liquid chromatography-mass spectrometry offers many advantages over traditional methods for protein quantitation, especially when dealing with transmembrane proteins that are often difficult to express or generate antibodies against. In this study, discovery proteomics was used to detect the seven transgenic membrane-bound enzymes from the docosahexaenoic acid (DHA) biosynthetic pathway that had been engineered into canola. Subsequently, a targeted LC-MS/MS method for absolute quantitation was developed and applied to the simultaneous measurement of the seven DHA biosynthetic pathway enzymes in genetically modified canola grown across three sites. The results of this study demonstrated that the enzymatic proteins that drive the production of DHA using seed-specific promoters were detected only in mature and developing seed of DHA canola. None of the DHA biosynthesis pathway proteins were detected in wild-type canola planted in the same site or in the non-seed tissues of the transgenic canola, irrespective of the sampling time or the tissues tested. This study describes a streamlined approach to simultaneously measure multiple membrane-bound proteins in planta.

Different effects of calcium and penconazole on primary and secondary metabolites of Brassica napus under drought

The effects of penconazole (PEN) and calcium (Ca²⁺) on physiological and biochemical parameters were investigated in two canola cultivars (RGS003 and Sarigol) under water stress. Drought increased protein content in RGS003, but PEN, Ca²⁺ and PEN-Ca²⁺ treatment induced protein content in Sarigol. PEN, Ca²⁺ and PEN-Ca²⁺ treatment enhanced soluble sugar content in RGS003. In contrast to Sarigol, drought and PEN treatment induced total phenol content in RGS003. Flavonoid content increased by drought, but Ca²⁺ and PEN-Ca²⁺ treatment decreased it in both cultivars. Ca²⁺ and PEN-Ca²⁺ treatment enhanced tocopherol content in both cultivars under drought stress. Drought stress increased Phenylalanine ammonia-lyase (PAL) activity in Sarigol. PEN-Ca²⁺ treatment increased relative expression of PAL and its activity in RGS003. Fatty acid composition was modified by drought, PEN and Ca²⁺. Saturated fatty acid (stearic acid) content declined but unsaturated fatty acid (oleic acid) content enhanced in both cultivars under drought. The application of PEN and Ca²⁺ decreased unsaturated fatty acids (linoleic and linolenic acid) in RGS003 under drought. According to our results, PEN and Ca²⁺ changed physiological and biochemical parameters and therefore these compounds are suggested for reduction of the negative effects of drought stress in canola.

Using artificial neural network to investigate physiological changes and cerium oxide nanoparticles and cadmium uptake by Brassica napus plants

Heavy metals and emerging engineered nanoparticles (ENPs) are two current environmental concerns that have attracted considerable attention. Cerium oxide nanoparticles (CeO₂NPs) are now used in a plethora of industrial products, while cadmium (Cd) is a great environmental concern because of its toxicity to animals and humans. Up to now, the interactions between heavy metals, nanoparticles and plants have not been extensively studied. The main objectives of this study were (i) to determine the synergistic effects of Cd and CeO₂NPs on the physiological parameters of Brassica and their accumulation in plant tissues and (ii) to explore the underlying physiological/phenotypical effects that drive these specific changes in plant accumulation using Artificial Neural Network (ANN) as an alternative methodology to modeling and simulating plant uptake of Ce and Cd. The combinations of three cadmium levels (0 [control] and 0.25 and 1 mg/kg of dry soil) and two CeO₂NPs concentrations (0 [control] and 500 mg/kg of dry soil) were investigated. The results showed high interactions of co-existing CeO₂NPs and Cd on plant uptake of these metal elements and their interactive effects on plant physiology. ANN also identified key physiological factors affecting plant uptake of co-occurring Cd and CeO₂NPs. Specifically, the results showed that root fresh weight and the net photosynthesis rate are parameters governing Ce uptake in plant leaves and roots while root fresh weight and F_v/F_m ratio are parameters affecting Cd uptake in leaves and roots. Overall, ANN is a capable approach to model plant uptake of co-occurring CeO₂NPs and Cd.

Simultaneous responses of photosystem II and soluble proteins of rapeseed to cold acclimation

This experiment was conducted to assess the quantitative and qualitative changes in soluble proteins as well as some chlorophyll fluorescence parameters in the leaves of a winter canola (Brassica napus L., cv. Licord) under continuous low temperature. Over the experiment, seedlings were initially grown at 15/10 °C (d/n). At fourth fully expanded leafy stage (day 30), a part of the plants were transferred to 4/2°C for 4 weeks. Plants were sampled for protein extraction from leaves in which chlorophyll fluorescence parameters (Fo, Fv, Fm, Fv/Fo, Fm/Fo, Fv/Fm, Fo´, FV´, Fm´ and some other calculated) were also measured. The results showed a clear increase in soluble proteins quantity caused by cold treatment. The enhancements appeared abruptly following the cold exposure to 4°C and lasted. The electrophoretic protein patterns showed changes in the intensity of some polypeptides, besides, induction a new probable protein weighing 47-kW in response to cold treatment. Cold-triggered reduction in maximum quantum yield of PSII (Fv/Fm) was connected especially with drastic decreasing Fv and Fm. Interestingly, high quantitative amounts of soluble proteins along with induction of the new probable polypeptide induced at cold temperature, were attributed to low deduction of maximum quantum yield of PSII. Additionally, more imperative chlorophyll fluorescence parameters changed e.g. qP, NPQ, qL, Y(II) or фPSII etc at light. Nowadays, radar charts or spider plots are the most sophisticated multivariate statistical tools representing physiological responses of plants to abiotic stress conditions or even morphophysiological studies of plants. In rapeseed many researches performed by applying the radar charts for low temperature stresses and interpreted their effects more advancely than common statistical tools. We observed a good representation of the chl fluorescence parameters fluctuations using radar plots. Overall, cold-induced soluble proteins accumulated after longer cold-acclimation, can contribute in photosynthetic apparatus protection against low-temperature damages.

Unravelling the effects of blue light on aerobic methane emissions from canola

It is now well documented that plants produce methane (CH₄) under aerobic conditions. However, the nature of methane production in plants and all the potential precursors and environmental factors that can be involved in the process are not fully understood. Earlier studies have suggested several chemical compounds, including the amino acid methionine, as precursors of aerobic methane in plants, but none have explored other amino acids as potential precursors or blue light as a driving force of methane emission. We examined the effects of blue light, and the promoter or inhibitor of endogenous ethylene on methane and ethylene emissions, amino acids, and some plant physiological parameters in canola (Brassica napus). Plants were grown under four light conditions: no supplemental blue light, and low, medium, or high blue light, and exposed to three chemical treatments: no chemical application, ethylene promoter (kinetin), or ethylene inhibitor (silver nitrate). Regardless of chemical treatment, blue light significantly increased methane emission, which was accompanied by decreased plant biomass, gas exchange, and flavonoids, but by increased wax, and most amino acids. This study revealed that blue light drives aerobic methane emission from plants by releasing of methyl group from a number of amino acids, and that the methane production in plants may have several pathways.

Comparative proteomic analysis of salt-responsive proteins in canola roots by 2-DE and MALDI-TOF MS

Salinity stress is a major abiotic stress that affects plant growth and limits crop production. Roots are the primary site of salinity perception, and salt sensitivity in roots limits the productivity of the entire plant. To better understand salt stress responses in canola, we performed a comparative proteomic analysis of roots from the salt-tolerant genotype Safi-7 and the salt-sensitive genotype Zafar. Plants were exposed to 0, 150, and 300 mM NaCl. Our physiological and morphological observations confirmed that Safi-7 was more salt-tolerant than Zafar. The root proteins were separated by two-dimensional gel electrophoresis and MALDI-TOF mass spectrometry was applied to identify proteins regulated in response to salt stress. We identified 36 and 25 protein spots whose abundance was significantly affected by salt stress in roots of plants from the tolerant and susceptible genotype, respectively. Functional classification analysis revealed that the differentially expressed proteins from the tolerant genotype could be assigned to 14 functional categories, while those from the susceptible genotype could be classified into 9 functional categories. The most significant differences concerned proteins involved in glycolysis (Glyceraldehyde-3-phosphate dehydrogenase, Fructose-bisphosphate aldolase, Phosphoglycerate kinase 3), stress (heat shock proteins), Redox regulation (Glutathione S-transferase DHAR1, L-ascorbate peroxidase), energy metabolism (ATP synthase subunit B), and transport (V-type proton ATPase subunit B1) which were increased only in the tolerant line under salt stress. Our results provide the basis for further elucidating the molecular mechanisms of salt-tolerance and will be helpful for breeding salt-tolerant canola cultivars.

Mesophyll Protoplasts and PEG-Mediated Transfections: Transient Assays and Generation of Stable Transgenic Canola Plants

Plant protoplasts are derived by controlled enzymatic digestion that removes the plant cell wall without damaging the cell membrane. Protoplasts represent a true single-cell system and are useful for various biochemical and physiological studies. Protoplasts from several agriculturally important crop species can be regenerated into a fertile whole plant, extending the utility of protoplasts from transient expression assays to the generation of stable transformation events. Here we describe procedures for transient and stable transformation of leaf mesophyll protoplasts obtained from axenic shoot cultures of canola (Brassica napus). Key steps including enzymatic digestion for protoplast release, density gradient-based protoplast purification, PEG-mediated transfection, bead-type culturing (sea-plaque agarose and sodium alginate), and the recovery of putative transgenic canola plants are described. This method has been used for double-stranded DNA break-mediated genome editing and for the routine generation of stable transgenic canola events at commercial scale.

Supplementation with plant-derived oils rich in omega-3 polyunsaturated fatty acids for lamb production

In this report, an overview of the health benefits of omega-3 long-chain (≥C20) polyunsaturated fatty acids (n-3 LC-PUFA) and recent progress in using alpha linolenic acid (ALA) rich sources derived from oilseeds to enhance productive performance, n-3 PUFA profiles and sensory properties of lamb for human consumption is reviewed. Omega-3 LC-PUFA can prevent mental health issues and chronic human disorders including cancer, cardiovascular and inflammatory diseases. The median amount of n-3 LC-PUFA consumption is generally lacking in Western diets. More attention is now being paid to the use of innovative nutritional strategies to improve PUFA content in ruminants, which could subsequently increase the content of health-benefitting n-3 LC-PUFA for human consumption. The richest sources of dietary n-3 LC-PUFA are derived from marine products, while forage and oilseeds such as flaxseed, canola, and their oils are abundant in ALA. Numerous studies have shown that dietary ALA increases n-3 LC-PUFA levels of edible tissues. However, other studies concluded that ALA rich supplementation led to no differences in tissue FA profiles because of extensive biohydrogenation of dietary ALA, limited conversion from ALA to n-3 LC-PUFA and low incorporation of n-3 LC-PUFA into edible tissues. Generally, the inclusion of ALA rich sources in lamb diets potentially increases ALA content in lamb. It is proposed that supplementing ruminants with ALA-rich sources at or below 6% can promote n-3 PUFA profiles in lamb and is unlikely to have negative effects on feed intake, growth, carcass and sensory properties.

Drought stress has transgenerational effects on seeds and seedlings in winter oilseed rape (Brassica napus L.)

BACKGROUND

Drought stress has a negative effect on both seed yield and seed quality in Brassica napus (oilseed rape, canola). Here we show that while drought impairs the maternal plant performance, it also increases the vigour of progeny of stressed maternal plants. We investigated the transgenerational influence of abiotic stress by detailed analysis of yield, seed quality, and seedling performance on a growth-related and metabolic level. Seeds of eight diverse winter oilseed rape genotypes were generated under well-watered and drought stress conditions under controlled-environment conditions in large plant containers.

RESULTS

We found a decrease in seed quality in seeds derived from mother plants that were exposed to drought stress. At the same time, the seeds that developed under stress conditions showed higher seedling vigour compared to non-stressed controls.This effect on seed quality and seedling vigour was found to be independent of maternal plant yield performance.

CONCLUSIONS

Drought stress has a positive transgenerational effect on seedling vigour. Three potential causes for stress-induced improvement of seedling vigour are discussed: (1) Heterotic effects caused by a tendency towards a higher outcrossing rate in response to stress; (2) an altered reservoir of seed storage metabolites to which the seedling resorts during early growth, and (3) inter-generational stress memory, formed by stress-induced changes in the epigenome of the seedling.

Physiological studies and genome-wide microRNA profiling of cold-stressed Brassica napus

Temperature extremes, including cold, adversely impact plant growth and development. Plant responses to cold stress (CS) are regulated at both transcriptional and post-transcriptional levels. MicroRNAs (miRNAs), small non-coding RNAs, are known to be involved in post-transcriptional regulation of various developmental processes and metal stress in Brassica napus L. (canola), however, their role in response to CS is largely unknown. In this study, changes in various physiological parameters and endogenous abundance of miRNAs were characterized in spring canola seedlings (DH12075) exposed to 4 °C for 0-48 h. Cold stress induced electrolyte leakage, increased the levels of malondialdheyde and antioxidant enzymes and reduced photosynthetic efficiency. Using small RNA sequencing, 70 known and 126 novel miRNAs were identified in CS leaf tissues and among these, 25 known and 104 novel miRNAs were differentially expressed. Quantitative real-time (qRT) PCR analysis of eight selected miRNAs confirmed their CS responsiveness. Furthermore, the expression of six out of eight miRNAs exhibited an opposite trend in a winter variety of canola, 'Mendel', when compared to 'DH12075'. This first study on the B. napus miRNAome provides a framework for further functional analysis of these miRNAs and their targets in response to CS which may contribute towards the future development of cold resilient crops.

Assessing the role of dispersed floral resources for managed bees in providing supporting ecosystem services for crop pollination

Most pollination ecosystem services studies have focussed on wild pollinators and their dependence on natural floral resources adjacent to crop fields. However, managed pollinators depend on a mixture of floral resources that are spatially separated from the crop field. Here, we consider the supporting role these resources play as an ecosystem services provider to quantify the use and availability of floral resources, and to estimate their relative contribution to support pollination services of managed honeybees. Beekeepers supplying pollination services to the Western Cape deciduous fruit industry were interviewed to obtain information on their use of floral resources. For 120 apiary sites, we also analysed floral resources within a two km radius of each site based on geographic data. The relative availability of floral resources at sites was compared to regional availability. The relative contribution of floral resources-types to sustain managed honeybees was estimated. Beekeepers showed a strong preference for eucalypts and canola. Beekeepers selectively placed more hives at sites with eucalypt and canola and less with natural vegetation. However, at the landscape-scale, eucalypt was the least available resource, whereas natural vegetation was most common. Based on analysis of apiary sites, we estimated that 700,818 ha of natural vegetation, 73,910 ha of canola fields, and 10,485 ha of eucalypt are used to support the managed honeybee industry in the Western Cape. Whereas the Cape managed honeybee system uses a bee native to the region, alien plant species appear disproportionately important among the floral resources being exploited. We suggest that an integrated approach, including evidence from interview and landscape data, and fine-scale biological data is needed to study floral resources supporting managed honeybees.

Comparative analysis of the genetic variability within the Q-type C2H2 zinc-finger transcription factors in the economically important cabbage, canola and Chinese cabbage genomes

Background

Brassica oleracea, B. rapa and B. napus encompass many economically important vegetable and oil crops; such as cabbage, broccoli, canola and Chinese cabbage. The genome sequencing of these species allows for gene discovery with an eye towards discerning the natural variability available for future breeding. The Q-type C2H2 zinc-finger protein (ZFP) transcription factors contain zinc finger motifs with a conserved QALGGH as part of the motif and they may play a critical role in the plants response to stress. While they may contain from one to five ZF domains (ZFD) this work focuses on the ZFPs that contain two zinc-fingers, which bind to the promoter of genes, and negatively regulate transcription via the EAR motif. B. oleracea and rapa are diploid and evolved into distinct species about 3.7 million years ago. B. napus is polyploid and formed by fusion of the diploids about 7500 years ago.

Results

This work identifies a total of 146 Q-type C2H2-ZFPs with 37 in B. oleracea, 35 in B. rapa and 74 in B. napus. The level of sequence similarity and arrangement of these genes on their chromosomes have mostly remained intact in B. napus, when compared to the chromosomes inherited from either B. rapa or oleracea. In contrast, the difference between the protein sequences of the orthologs of B. rapa and oleracea is greater and their organization on the chromosomes is much more divergent. In general, the 146 proteins are highly conserved especially within the known motifs. Differences within subgroups of ZFPs were identified. Considering that B. napus has twice the number of these proteins in its genome, RNA-Seq data was mined and the expression of 68 of the 74 genes was confirmed.

Conclusion

Alignment of these proteins gives a snapshot of the variability that may be available naturally in Brassica species. The aim is to study how different ZFPs bind different genes or how dissimilar EAR motifs alter the negative regulation of the genes bound to the ZFP. Results from such studies could be used to enhance tolerance in future Brassica breeding programs.

Electronic supplementary material

The online version of this article (10.1186/s41065-018-0065-5) contains supplementary material, which is available to authorized users.

Effects of dietary humic acid and enzymes on meat quality and fatty acid profiles of broiler chickens fed canola-based diets

Objective

This study was conducted to assess the effect of potassium humate and enzymes (Xylanase+Amylase+Protease) inclusion in diets on carcass characteristics, meat quality and fatty acid profiles of broilers fed canola-based diets.

Methods

Two hundred and twenty broilers randomly allotted to 5 dietary treatments: the control (commercial broiler diet); CM (17.5% canola meal inclusion); CMEnz (17.5% CM inclusion+0.3 g/kg Axtra XAP); CMPh (17.5% CM inclusion+1.5% Potassium Humate, PH); and CMEnzPh (17.5% CM inclusion+1.5% PH+0.3 g/kg Axtra XAP) were slaughtered at day 42 for assessment of carcass and meat quality parameters.

Results

Diet had no effect on carcass traits apart from breast muscle weight and breast muscle index. The highest breast muscle weight was observed in broilers fed CMEnz (487.6±17.5 g) followed by those fed the control diet (474.37±17.5 g). Diet also had no significant dietary effect on pH, temperature, drip loss and shear force values of the breast muscle. However, diet significantly affected meat colour and water-holding capacity. Broilers in the control and CMPh groups (52.94±0.67 and 52.91±0.67) had the highest (p<0.05) values for lightness (L*), whilst those fed CMEnzPh had the lowest value (47.94±0.67). In contrast, CM group had the lowest (p<0.05) value for redness (a*) with CMEnzPh group having the highest values. The proportion of polyunsaturated fatty acids (PUFAs), n-6 and n-3 fatty acids and the PUFA/saturated fatty acid ratio were increased in CM-based diets containing enzymes and humic acid.

Conclusion

It can, therefore, be concluded that CM can be included in broiler diets in the presence of enzymes and humic acid with positive effects on meat quality and important fatty acids that are beneficial to the health of consumers.

Improving tolerance against drought in canola by penconazole and calcium

Drought stress is one of the most important environmental factors that limit plant growth. Canola is an important agricultural crop grown primarily for its edible oil. In this study, penconazole (PEN), a triazole growth regulator, and calcium (Ca²⁺), a secondary messenger, were used to analyses their role in decease sensitivity and induce tolerance to drought stress in canola. Plants were treated by various PEG concentrations (0, 5, 10, and 15%) without or with PEN (15 mg l^-1) and Ca²⁺ (15 mM). According to the obtained results in two cultivars of canola (RGS003 and Sarigol), improvement of growth by PEN and Ca²⁺observed at low concentration of drought (5%). Betterment of growth by PEN can be explained by induction in DPPH (1, 1-diphenyl-2- picrylhydrazyl), chlorophyll and P content and reduction in Electrolyte leakage in cultivar RGS003. Growth recovery by PEN is concomitant by increase in DPPH, succinate dehydrogenase, chlorophyll, carotenoid and K⁺ content in cultivar Sarigol. Ca²⁺ treatment by induction in Relative water content, DPPH, chlorophyll, carotenoid, indole-3-acetic acid content and the content of Ca²⁺ and K⁺ causes increase in growth in cultivar Sarigol. Overall, application of PEN and Ca²⁺ improved the performance in canola under drought stress. These results provide novel insights about the physiological and molecular roles of PEN and Ca²⁺ in canola plant tolerance against drought stress.

GIS assessment of the risk of gene flow from Brassica napus to its wild relatives in China

Risk of gene flow from canola (Brassica napus) to species of wild relatives was used as an example to evaluate the risk of gene flow of transgenic crops. B. juncea and B. rapa were the most common weedy Brassica species in China, which were both sexually compatible with canola. Data on canola cultivation in China were collected and analyzed using geographic information system (GIS), and the distribution of its wild relatives was predicted by MaxEnt species distribution model. Based on biological and phenological evidence, our results showed that gene flow risk exists in most parts of the country, especially in places with higher richness of wild Brassica species. However, risk in dominant canola cultivation regions is relatively low owing to the reduced distribution density of wild species in these regions. Three regions of higher risk of gene flow had been identified. Risk of gene flow is relatively high in certain areas. China has been assumed to be the original center of B. juncea and B. rapa, and gene flow may lead to negative effects on the conservation of biodiversity of local species. Strategies had been proposed to reduce the possibility of gene flow either by monitoring introgression from crops to wild relatives in the areas of high adoption of the crop or by taking measures to limit the releasing of new crops or varieties in the areas with abundant wild relatives.

Metabolomic analysis of pollen from honey bee hives and from canola flowers

BACKGROUND AND AIMS

Pollen is essential for successful plant reproduction and critical for plant-pollinator mutualisms, as pollen is essential larval nutrition. However, we understand very little about the chemical constituents of pollen leading us to this exploratory study characterizing plant and beehive pollen.

METHODS

We performed a metabolomics assay of canola flower pollen and beehive pollen.

RESULTS AND DISCUSSION

The metabolome of canola pollen is affected by irrigation showing differences in lipids and non-polar secondary metabolites. Metabolome of beehive pollen is affected by plant source showing differences in pentose sugars, myo-inositol and furanose. Further research is needed to document the nutritional bases of plant-pollinator mutualism.

Alkaline treatment of resting spores prior to DNA extraction improves the purity of Plasmodiophora brassicae DNA

A commonly used protocol for DNA extraction from Plasmodiophora brassicae was modified by adding an alkaline treatment step to increase the purity of resting spores. The quality of DNA extracted by the modified protocol was improved due to the removal of DNA contamination from host plant cells and other microorganisms.

Taxonomy and pathogenicity of Olpidium brassicae and its allied species

The classification and physiology of the zoosporic plant-pathogen Olpidium brassicae and its relationships with the closely-related species are often confusing. This review focuses on these species and intends to differentiate them based on the literatures published since the discovery and establishment of the species by Woronin in 1878 under the name of Chytridium brassicae to current molecular era. The goal of this review is to help researchers better understand the taxonomy, the host range, and the potential role in plant health of O. brassicae-related species. To reach the goal, we reviewed the rationales behind the creation or reduction in synonymy of the different names for O. brassicae and its allied species in order to elucidate the evolution of the species concept on them based on the traditional morphological studies. Furthermore, the studies by molecular biology methods improve our knowledge and perspectives on O. brassicae and its host specificity. In particular, we clarify the differences between O. brassicae and Olpidium virulentus, and propose potential new research avenues. We therefore hope that this review will give a better perspective on Olpidium spp. and their potential role in the root microbiome of plants in natural environments and in agricultural settings.

Effect of endogenous reference genes on digital PCR assessment of genetically engineered canola events

Droplet digital PCR (ddPCR) has been used for absolute quantification of genetically engineered (GE) events. Absolute quantification of GE events by duplex ddPCR requires the use of appropriate primers and probes for target and reference gene sequences in order to accurately determine the amount of GE materials. Single copy reference genes are generally preferred for absolute quantification of GE events by ddPCR. Study has not been conducted on a comparison of reference genes for absolute quantification of GE canola events by ddPCR. The suitability of four endogenous reference sequences (HMG-I/Y, FatA(A), CruA and Ccf) for absolute quantification of GE canola events by ddPCR was investigated. The effect of DNA extraction methods and DNA quality on the assessment of reference gene copy numbers was also investigated. ddPCR results were affected by the use of single vs. two copy reference genes. The single copy, FatA(A), reference gene was found to be stable and suitable for absolute quantification of GE canola events by ddPCR. For the copy numbers measured, the HMG-I/Y reference gene was less consistent than FatA(A) reference gene. The expected ddPCR values were underestimated when CruA and Ccf (two copy endogenous Cruciferin sequences) were used because of high number of copies. It is important to make an adjustment if two copy reference genes are used for ddPCR in order to obtain accurate results. On the other hand, real-time quantitative PCR results were not affected by the use of single vs. two copy reference genes.

Current status and future possibilities of molecular genetics techniques in Brassica napus

As PCR methods have improved over the last 15 years, there has been an upsurge in the number of new DNA marker tools, which has allowed the generation of high-density molecular maps for all the key Brassica crop types. Biotechnology and molecular plant breeding have emerged as a significant tool for molecular understanding that led to a significant crop improvement in the Brassica napus species. Brassica napus possess a very complicated polyploidy-based genomics. The quantitative trait locus (QTL) is not sufficient to develop effective markers for trait introgression. In the coming years, the molecular marker techniques will be more effective to determine the whole genome impairing desired traits. Available genetic markers using the single-nucleotide sequence (SNP) technique and high-throughput sequencing are effective in determining the maps and genome polymorphisms amongst candidate genes and allele interactions. High-throughput sequencing and gene mapping techniques are involved in discovering new alleles and gene pairs, serving as a bridge between the gene map and genome evaluation. The decreasing cost for DNA sequencing will help in discovering full genome sequences with less resources and time. This review describes (1) the current use of integrated approaches, such as molecular marker technologies, to determine genome arrangements and interspecific outcomes combined with cost-effective genomes to increase the efficiency in prognostic breeding efforts. (2) It also focused on functional genomics, proteomics and field-based breeding practices to achieve insight into the genetics underlying both simple and complex traits in canola.

Aminolevulinic acid and nitric oxide regulate oxidative defense and secondary metabolisms in canola (Brassica napus L.) under drought stress

To minimize the damaging effects of stresses, plant growth regulators (PGRs) are widely used to sustain the plant life under stress-prone environments. So, a study was carried out to evaluate the response of two canola (Brassica napus L.) cultivars, Dunkeld and Cyclone, to foliar-applied two potential PGRs, nitric oxide (NO) and 5-aminolevulinic acid, under water deficit conditions. In this study, the levels of NO and ALA used were 0.02 and 0.895 mM, respectively. Plants of both canola cultivars were subjected to control (100% field capacity) and water deficit (60% field capacity). Drought stress significantly decreased growth, chlorophyll pigments, relative water contents (RWC), and soluble proteins, while it increased relative membrane permeability (RMP), proline, glycinebetaine (GB), malondialdehyde (MDA), total phenolics, and activities of catalase (CAT) and peroxidase (POD) enzymes in both cultivars. Foliar application of PGRs improved growth, chlorophyll a, GB, total phenolics, CAT activity, and total soluble proteins, while it decreased RMP, MDA, and POD activity in both canola cultivars. Other physio-biochemical attributes such as chlorophyll b, RWC, hydrogen peroxide (H₂O₂) and proline contents as well as superoxide dismutase (SOD) activity remained unaffected due to application of PGRs. So, the results of the present study suggest that exogenous application of NO and ALA could be useful to enhance the drought tolerance of canola plants by up-regulating the oxidative defense system, osmoprotectant accumulation, and minimizing the lipid peroxidation.