Canola Cultivars Research Articles

UA CountyGold imidazoline herbicide-resistant nontransgenic open-pollinated spring Brassica napus canola

UA CountyGold is an imidazoline herbicide-resistant open-pollinated nontransgenic spring Brassica napus L. canola cultivar developed from UA BountyGold × UA AlfaGold cross following pedigree breeding method and registered in Canada in 2021. The pedigree of UA CountyGold contains winter canola germplasm. On average, UA CountyGold yielded 3152 kg ha− 1. It flowered and matured 4.5–6.5 days later; however, it had better straw stiffness than the Western Canada Canola/Rapeseed Recommending Committee (WCC/RRC) check cultivars. This cultivar had about 0.9% higher oil in seed and 1.5% higher protein in meal, and 0.7% lower saturated fatty acids in the seed oil than the WCC/RRC checks, and rated as moderately resistant to blackleg disease.

Optimization of chromatographic buffer conditions for the simultaneous analysis of phosphatidylinositol and phosphatidylinositol phosphate species in canola.

The phosphatidylinositols and phosphatidylinositol phosphates are a set of closely related lipids known to influence various cellular functions. Irregular distributions of these molecules have been correlated with the development and progression of multiple diseases, including Alzheimer's, bipolar disorder, and various cancers. As a result, there is continued interest regarding the speciation of these compounds, with specific consideration on how their distribution may differ between healthy and diseased tissue. The comprehensive analysis of these compounds is challenging due to their varied and unique chemical characteristics, and current generalized lipidomics methods have proven unsuitable for phosphatidylinositol analysis and remain incapable of phosphatidylinositol phosphate analysis. Here we improved upon current methods by enabling the sensitive and simultaneous analysis of phosphatidylinositol and phosphatidylinositol phosphate species, whilst enhancing their characterization through chromatographic resolution between isomeric species. A 1mM ammonium bicarbonate and ammonia buffer was determined optimal for this goal, enabling the identification of 148 phosphatidylinositide species, including 23 lyso-phosphatidylinositols, 51 phosphatidylinositols, 59 oxidized-phosphatidylinositols, and 15 phosphatidylinositol phosphates. As a result of this analysis, four distinct canola cultivars were differentiated based exclusively on their unique phosphatidylinositide-lipidome, indicating analyses of this type may be of use when considering the development and progression of the disease through lipidomic profiles.

Sustainability on Different Canola (Brassica napus L.) Cultivars by GGE Biplot Graphical Technique in Multi-Environment

Knowledge about the extent of genotype in environment interaction is helpful for farmers and plant breeders. This is because it helps them choose the proper strategies for agricultural management and breeding new cultivars. The main contribution of this paper is to investigate genotype on environmental interaction using the GGE biplot method (Genotype and the Genotype-by-Environment) in ten canola cultivars. The experimental design was a randomized complete block design (RCBD) with three replications to assess the stability of grain yield of ten canola cultivars in five regions of Iran, including Birjand, Karaj, Kashmar, Sanandaj, and Shiraz, within two agricultural years of 2016 and 2017. The results of combined ANOVA illustrated that the effects of the environment, genotype × environment, and genotype were highly significant at 1%. Variance Analysis showed that three environmental impacts, genotype, and interaction of genotype in the environment effect, produced 68.44%, 18.63%, and 12.9% of the total variance. The GGE biplot graphs were constructed using PCA. The first principle component (PC1) explained 65.3%, and the second (PC2) explained 18.8% of the total variation. The research examined polygon diagrams to identify two top genotypes and four mega-environments. Also, the appropriate genotypes for each environment were diagnosed. Using the GGE biplot, it was possible to make visual comparisons and identify superior genotypes in canola. Accordingly,. The results obtained from graphical analysis indicated that Licord, Hyola 401 and Okapi genotypes showed the highest yield and were selected as the most stable genotypes. Also, Karaj region was chosen as a experimental region where the screening of genotypes was very suitable. Based on the ranking of the genotypes in the most suitable region (Karaj), Okapi genotype was selected as the desired genotype. In examining the heatmap drawn between the genotypes and the investigated environments, a lot of similarity between the genotypes of Sarigal, Hyola 401 and Okapi was observed in the investigated environments. The GGE biplot graphs enabled the detection of stable and superior environments and the grouping of cultivars and environments based on grain yield. The results of this research can be used both for extension and for future breeding programs. Our results provide helpful information about the canola genotypes and environments for future breeding programs.

Characterization of Plasmodiophora brassicae pathotypes from western Canada in 2019–2020

Clubroot, caused by Plasmodiophora brassicae, is a major soilborne disease of canola (Brassica napus) on the Canadian Prairies. Most canola cultivars carry what is now referred to as ‘first-generation’ resistance, which represents the most widely used clubroot management tool. Unfortunately, new pathotypes of P. brassicae have emerged that can overcome this resistance. By 2018, 36 unique pathotypes of P. brassicae had been identified on the Prairies based on their virulence on the Canadian Clubroot Differential (CCD) set, with pathotypes 3A, 3D and 3 H being predominant. Since the virulence of P. brassicae populations can shift rapidly in response to host selection pressure, continued pathotype monitoring is important for resistance stewardship. Clubbed roots were collected from 133 canola crops (126 in Alberta, 6 in Saskatchewan, 1 in Manitoba) in 2019 and 127 crops (113 in Alberta, 13 in Saskatchewan, 1 in Manitoba) in 2020, and evaluated for their CCD pathotype designations. Twenty-five unique pathotypes were identified across the sampled crops over the two years of the study; these included seven novel pathotypes, six of which could overcome first-generation resistance (3C, 8 G, 8I, 9D, 9E and 9F). While pathotypes 3A, 3D and 3 H continued to be identified frequently in 2019 and 2020, several others, most notably pathotype 8E (virulent on hosts with first-generation resistance), had also become more common by 2020. The results indicate the continued emergence of new P. brassicae pathotypes on canola.

Phytochemical analysis of canola (Brassica napus L.) Cultivars: Mitigating lead stress effects through the foliar spray of potassium chloride

In the Botanical Garden and Research Laboratory of the Institute of Pure and Applied Biology, Bahauddin Zakariya University, Multan (Pakistan) the current work was performed to examine the effect of the foliar spray of potassium for lessening the toxicity of heavy metal in three varieties of Canola (Brassica napus L.) viz; Exceed, Cyclone and Legend. Seeds were grown in pots. They were arranged in a Completely Randomized Design (CRD). When seeds germinated, some were kept without treatment (control) and others were treated with 15mg/kg and 30mg/kg of Lead along with a Potassium spray. Plants were harvested and subjected to phytochemical studies. The role of phytochemical studies (alkaloid, flavonoid, and phenolic) showed an increase in response against heavy metal stress. While the plants treated with Potassium revealed a decreased response in phytochemical studies. Plants treated with both Pb metal and K expressed a lesser increase in phytochemical compared to plants only treated with metal. This study sheds light on the effectiveness of Potassium in improving growth and dealing with metal stress to decrease the harmful effect of heavy metals. However, further studies are required to identify the mechanisms of Potassium mediated alleviation of toxicity of Pb and other heavy metals. Keywords: Alkaloid; Canola; Lead; Potassium; Phytochemicals

Screening of canola (Brassica napus L.) cultivars for nickel stress tolerance

The present study was conducted to evaluate variation in nickel stress tolerance in a set of 10 canola cultivars (Leand, AC Excel, Faisal Canola, Shiralee, Oscar, Punjab Canola, CON-II, Rainbow, Dunkeld, and Cyclone) at the early growth stages, i.e., germination and seedling stage. The seeds of all canola cultivar were obtained from the Ayub Agricultural Research Institute, Faisalabad, Pakistan. Ten seeds of each cultivar were sown in each of Petri plates moistened with varying levels (15, 30 and 45 mg/L) of nickel in Hoagland nutrient solution. Data for different growth indices were recorded such as germination stress index (GSI), shoot length stress index (SLSI), root length stress index (RLSI), and seedling fresh (SFWI) and seedling dry weight indices (SDWI). Based on different growth indices, three canola cultivars, i.e., CON-II, Faisal Canola and Leand proved to be potential source of variation for Ni tolerance provided if they maintain their degree of Ni tolerance at the later growth stages. However, Oscar was the most sensitive to Ni stress of all 10 cultivars evaluated in the current study.

Morphological, biochemical, and physiological responses of canola cultivars to drought stress

Morphological, biochemical, and physiological responses of canola cultivars to drought stress

Exogenously Applied Silicon and Zinc Mitigates Salt Stress by Improving Leaf Pigments and Antioxidant Activities in Canola Cultivars

Exogenously Applied Silicon and Zinc Mitigates Salt Stress by Improving Leaf Pigments and Antioxidant Activities in Canola Cultivars

Overwintering Camelina and Canola/Rapeseed Show Promise for Improving Integrated Weed Management Approaches in the Upper Midwestern U.S.

Winter oilseed cash cover crops are gaining popularity in integrated weed management programs for suppressing weeds. A study was conducted at two field sites (Fargo, North Dakota, and Morris, Minnesota) to determine the freezing tolerance and weed-suppressing traits of winter canola/rapeseed (Brassica napus L.) and winter camelina [Camelina sativa (L.) Crantz] in the Upper Midwestern USA. The top 10 freezing tolerant accessions from a phenotyped population of winter canola/rapeseed were bulked and planted at both locations along with winter camelina (cv. Joelle) as a check. To phenotype our entire winter B. napus population (621 accessions) for freezing tolerance, seeds were also bulked and planted at both locations. All B. napus and camelina were no-till seeded at Fargo and Morris at two planting dates, late August (PD1) and mid-September (PD2) 2019. Data for winter survival of oilseed crops (plants m-2) and their corresponding weed suppression (plants m-2 and dry matter m-2) were collected on two sampling dates (SD) in May and June 2020. Crop and SD were significant (p < 0.05) for crop plant density at both locations, and PD in Fargo and crop x PD interaction in Morris were significant for weed dry matter. At Morris and Fargo, PD1 produced greater winter B. napus survival (28% and 5%, respectively) and PD2 produced higher camelina survival (79% and 72%, respectively). Based on coefficient of determination (r2), ~50% of weed density was explained by camelina density, whereas ≤20% was explained by B. napus density at both locations. Camelina from PD2 suppressed weed dry matter by >90% of fallow at both locations, whereas weed dry matter in B. napus was not significantly different from fallow at either PD. Genotyping of overwintering canola/rapeseed under field conditions identified nine accessions that survived at both locations, which also had excellent freezing tolerance under controlled conditions. These accessions are good candidates for improving freezing tolerance in commercial canola cultivars.

Interactive effects of melatonin and salicylic acid on Brassica napus under drought condition

It is imperative to understand the synergetic actions of Melatonin (MET) and salicylic acid (SA) in counteracting drought stress. A pot experiment was performed to investigate the interactive effects of exogenously applied MET and SA on morphology, physiology, and biochemical characteristics of drought-stressed canola (Brassica napus). Two cultivars (Super canola and Faisal canola) were used. MET (0.1 µM) and SA (0.50 mM) were applied as seed priming and foliar spray. Plants were exposed to severe drought (45% field capacity) at the reproductive stage. Drought stress caused a significant reduction in shoot length (19%), plant fresh (15%) and dry (17%) biomass, yield (30%), photosynthetic rate (43%), water potential (29%) and osmotic potential (33%) values. Increased activity of free amino acids (20%), total soluble sugars (5%), and different antioxidant enzymes like catalase (27%), peroxidase (23%), superoxide dismutase (20%) and ascorbate peroxidase (35%), were recorded under drought. Seed priming and foliar application of MET and SA reduced the negativity of drought. Priming of seeds with MET, as well as synergetic application of MET priming and SA foliar spray, were the most effective treatments, showing the most significant growth criteria (22% increase in plant height, 46% in fresh and 40% in dry biomass), yield components (49%), water (54%) and osmotic potential (28%), and endogenous MET (17%) and SA (16%) content. Super canola cultivar showed better growth than Faisal canola. Study showed that the synergetic application of MET and SA has the potential to induce stress resistance and enhance canola plants' growth under drought.

Quantitative Trait Loci for Genotype and Genotype by Environment Interaction Effects for Seed Yield Plasticity to Terminal Water-Deficit Conditions in Canola (Brassica napus L.)

Canola plants suffer severe crop yield and oil content reductions when exposed to water-deficit conditions, especially during the reproductive stages of plant development. There is a pressing need to develop canola cultivars that can perform better under increased water-deficit conditions with changing weather patterns. In this study, we analysed genetic determinants for the main effects of quantitative trait loci (QTL), (Q), and the interaction effects of QTL and Environment (QE) underlying seed yield and related traits utilising 223 doubled haploid (DH) lines of canola in well-watered and water-deficit conditions under a rainout shelter. Moderate water-deficit at the pre-flowering stage reduced the seed yield to 40.8%. Multi-environmental QTL analysis revealed 23 genomic regions associated with days to flower (DTF), plant height (PH) and seed yield (SY) under well-watered and water-deficit conditions. Three seed yield QTL for main effects were identified on chromosomes A09, C03, and C09, while two were related to QE interactions on A02 and C09. Two QTL regions were co-localised to similar genomic regions for flowering time and seed yield (A09) and the second for plant height and chlorophyll content. The A09 QTL was co-located with a previously mapped QTL for carbon isotope discrimination (Δ13C) that showed a positive relationship with seed yield in the same population. Opposite allelic effects for plasticity in seed yield were identified due to QE interactions in response to water stress on chromosomes A02 and C09. Our results showed that QTL's allelic effects for DTF, PH, and SY and their correlation with Δ13C are stable across environments (field conditions, previous study) and contrasting water regimes (this study). The QTL and DH lines that showed high yield under well-watered and water-deficit conditions could be used to manipulate water-use efficiency for breeding improved canola cultivars.

Effects of Seed Priming and Foliar Treatment with Ascorbate, Cysteine, and Triacontanol on Canola (Brassica napus L.) under Field Conditions

Studies conducted in controlled environments showed that seed priming and foliar treatments with various bioactive substances can stimulate germination, uniform seedling emergence, photosynthesis, and nutrient uptake efficiency and can lead to increased productivity, crop stand, and quality. Only a few studies provide a comparative experimental outlook about the use of the bioactive substances in open-field cultivated canola. The aim of this study was to investigate the effects of seed priming and foliar treatment with ascorbate (AsA), cysteine (Cys), and triacontanol (Tria) on the growth and yield parameters of two canola cultivars rapeseed cultivars (“Factor” and “Hybrirock”) under open-field conditions for three growing seasons under temperate conditions from Central Transylvania. Plant growth and yield parameters were recorded at different plant development stages: in autumn (early vegetative period), in spring, and at harvest. Not all substances that have undergone laboratory testing were successful in the field. Seed priming with 10 ppm Cys and AsA had beneficial effects on the development of seedlings, whereas their foliar application enhanced the number of silique, seed yield, and the oil content of the studied canola cultivars. The effects of Tria were visible on the biometrics parameters only in autumn and spring, and also on the root parameters, but in some cases, 10 ppm Tria had no effect on plants, or even a negative effect could be observed on important parameters for agriculture such as estimated seed yield, seed yield/plant, and oil content. Optimizing treatment and application by determination of the lowest effective concentration, together with the frequency of treatments and persistence effects are crucial for cost-effectiveness.

Modeling root water uptake patterns of oil crops grown on semiarid loess

Oil crops are often used as cover crops by smallholders managing orchards on drylands, because they have an economic return and help regulate ecosystem services. Improving the ability of models in root water uptake (RWU) simulation is important to find the right crop species and predict the dynamics of these oil crops in water-limited regions. In this study, two different process-based models were used to simulate the RWU of three oil crops, i.e. soybean (Glycine max L., SYB) and two canola cultivars (turnip type rape (Brassica campestris L.), TTR, and cabbage type rape (Brassica napus L.), CTR), grown on the semiarid Loess Plateau of China, based on two-year in-situ measurements. The first model, IM-SVD, was developed by inverse modeling (IM) of the Richards equation and incorporating singular value decomposition (SVD) parameter optimization algorithms, which simulated the RWU pattern (including soil evaporation and plant transpiration). The second model was the Feddes model implemented in one-dimensional HYDRUS (HYDRUS 1-D). Both models reliably predicted the soil water content (SWC) in different layers. However, the IM-SVD model showed better modeling accuracy of SWC, and produced higher simulated RWU values than the HYDRUS 1-D model irrespective of crop. The results from both models implied that SYB had a higher daily and seasonal RWU than TTR and CTR, and its water source was derived mainly from the top 30 cm soil layer. Additionally, the simulated RWU was positively and significantly (p<0.05) correlated with fine root length density (FRLD). The RWU showed lagged correlations with SWC, which varied between crop species and growth stages, but overall were more positively correlated with the SWC on preceding days and more negatively correlated with the SWC on subsequent days. Our study provides insights into the improving RWU simulation for oil crops and similar crops in drylands.

Identification of Sources of Resistance to Clubroot (Plasmodiophora brassicae) in a Collection of Brassica napus Plant Introductions

Clubroot is a soilborne disease caused by Plasmodiophora brassicae that is emerging as a production problem in North Dakota, which contributes approximately 90% of the total U.S. canola production. P. brassicae’s resiliency in the soil and its ability to overcome the genetic resistance available in commercial hybrids make this a significant threat to canola production in the state and highlight the need to identify additional sources of resistance. To this effect, 115 Brassica napus plant introduction accessions were evaluated for their reaction to clubroot in field trials conducted between 2019 and 2021 in a naturally infested field. Seven accessions with high levels of clubroot resistance were identified. These resistant materials may contribute to widening the genetic resistance base of modern canola cultivars.

The Effect of Different Nitrogen Doses on Yield and Quality of Some Winter Canola (Brassica napus L.) Cultivars

This research was carried out to determine the effect of different nitrogen doses on yield and yield components of winter canola cultivars in Konya conditions during the winter canola growing vegetation period of 2019-2020. Three winter canola cultivars (Linus, PR44W29, Es Neptune) were used as material and six different nitrogen doses (0, 50, 100, 150, 200, 250 kg N ha-1) were applied. The research was established to according to the experimental design of split plots in randomized blocks. Half of the nitrogen fertilizer applications were given in the form of ammonium sulfate (21% N) at planting and the remaining half was given as urea (46% N) at the beginning of flowering. As a result of the study, it was determined that plant height, number of branch on the main stem, number of capsule per plant, capsule length, thousand seed weight seed yield, crude oil yield and crude protein ratio increased, while crude oil ratio decreased in winter canola varieties due to increasing nitrogen doses. As a matter of fact, the plant height values varied between 92.6 and 128.5 cm (respectively, LinusxN50 and PR44W29xN250), number of branch (no. main stem-1) of 2.4-5.7 (LinusxN0-PR44W29xN250), number of capsule (no. plant-1) of 103.9-218.9 (Es-NeptunexN0-PR44W29xN150), capsule size of 5.3-6.6 cm (Es-NeptunexN0-LinusxN250), number of seeds in the capsule of 22.5-30.0 (Es-NeptunexN100-PR44W29xN250), thousand seed weight between 3.2 and 4.7 g (PR44W29xN0-LinusxN200), seed yield of 1361-5373 kg ha-1 (Es-NeptunexN0-PR44W29xN250), crude oil yield between 547.0 and 2466.0 kg ha-1 (Es-NeptunexN0- PR44W29xN150) and crude protein ratio values ranged of 16.2 23.9% (Es-NeptunexN0-LinusxN200).It was determined that there were increases in the values of these properties with increasing nitrogen doses in general. In terms of crude oil ratio, the lowest value was determined at PR44W29xN0 with 39.2%, and the highest value was determined at PR44W29xN50 with 46.3%. It has been determined that there are relatively decreases in crude oil ratios with increasing nitrogen doses. The main purpose of cultivation of oil seed crops is to increase the oil yield per unit area. From this point of view, it was concluded that PR444W29 cultivar among the cultivars considered in the study would be more suitable in terms of oil yield with 150 kg N ha-1 application for the regions similar to the conditions in which the study was conducted.

Photosynthesis and Salt Exclusion Are Key Physiological Processes Contributing to Salt Tolerance of Canola (Brassica napus L.): Evidence from Physiology and Transcriptome Analysis.

Plant salt tolerance is controlled by various physiological processes such as water and ion homeostasis, photosynthesis, and cellular redox balance, which are in turn controlled by gene expression. In the present study, plants of six canola cultivars (DGL, Dunkled, Faisal Canola, Cyclone, Legend, and Oscar) were evaluated for salt tolerance by subjecting them to 0 or 200 mM NaCl stress. Based on growth, cultivars DGL, Dunkled, and Faisal Canola were ranked as salt tolerant, while cultivars Cyclone, Legend, and Oscar were ranked as salt-sensitive ones. Differential salt tolerance in these canola cultivars was found to be associated with a relatively lower accumulation of Na+ and greater accumulation of K+ in the leaves, lower oxidative damage (MDA), and better antioxidative defense system (Superoxide dismutase, SOD; peroxidase, POD, and catalase, CAT). Cultivar Oscar was the poorest to discriminate Na+ and K+ uptake and accumulation in leaves and had poor antioxidant potential to scavenge ROS. Salt stress did not affect the structural stability of photosystem-II (PSII) till three weeks, thereafter it caused a significant decrease. Salt stress increased the performance index (PIABS) by increasing the density of active reaction centers in Oscar. Salt stress decreased the antenna size thereby lowering the absorption and trapping energy flux, and maintaining the electron transport with an increase in heat dissipation. This may represent a potential mechanism to cope with salt stress. Transcriptome analysis of salt-sensitive cultivar Oscar further revealed that salt stress down-regulated DEGs related to hormonal signal transduction pathways, photosynthesis, and transcription factors, while DEGs related to the biosynthesis of amino acid and ion transport were up-regulated. In conclusion, salt tolerance in canola cultivars was associated with ion exclusion and maintenance of photosynthesis. Salt stress sensitivity in cultivar Oscar was mainly associated with poor control of ion homeostasis which caused oxidative stress and reduced photosynthetic efficiency.

An optimized biofumigant improves pepper yield without exerting detrimental effects on soil microbial diversity

BackgroundBiofumigation is a non-chemical sustainable approach that reshapes soil microbiota to overcome challenges in way of continuous cultivation. However, the type and quantity of substrate have a significant impact on microbiota shifts and the subsequent success of biofumigation. Moreover, studies on the effects of biofumigant concentration in combination with fumigation duration on soil microbiota dynamics are very rare.Research methodsWe performed microcosm experiments to investigate how a biofumigant (Korean canola cultivar, HanRa) at various concentrations (0.5%, 1%, 2–4% w/w: biofumigant/soil) and fumigation periods (2–4 weeks) affects the soil bacterial and fungal communities. Subsequently, pot experiments employing two Korean canola cultivars (HanRa and YongSan) at 1% (w/w) were carried out.ResultsIllumina MiSeq analysis revealed that 2–4% biofumigant, regardless of incubation period, had a significant negative impact on microbial diversity and network complexity. In contrast, 1% biofumigant transformed the bacterial, fungal, and inter-kingdom networks into a highly connected and complex network without affecting microbial diversity. Bacillus, Clostridium, and Pseudomonas were the most highly stimulated bacterial genera in the biofumigated soils, whereas the abundance of Acidobacteria members was greatly reduced. The 2–4% amendments had substantially and more differentially abundant Fusarium than the 1%. Soil nutrition (e.g., pH, nitrate, ammonium, and exchangeable potassium), fruit yield, and weed suppression were enhanced in subsequent pot experiments. Of the nine soil chemical properties, phosphate and exchangeable potassium were the main factors influencing the microbial community assembly.ConclusionsOptimized biofumigation-mediated increase in nitrate, ammonium, and potassium availability in the soil without causing any negative effects on soil microbial diversity indicates its potential as a preplant to improve crop productivity. This study contributes significantly to our understanding of how an optimal biofumigant can help ameliorate obstacles in continuous cropping.Graphical

A review of the genetic, physiological, and agronomic factors influencing secondary dormancy levels and seed vigour in Brassica napus L.

Dormancy in canola ( Brassica napus L.) is a complicated process due to many overlapping and interacting factors affecting the absolute dormancy levels. It is unknown if seed dormancy plays a role in the poor stand establishment of planted canola but given that germination and dormancy are two ends of the same continuum, it has been suggested that dormancy may be a culprit of poor establishment. This review synthesizes literature pertaining to secondary dormancy in B. napus and the interaction of genetic, physiological, environmental, and agronomic factors. Seed germination and vigour and the interaction with dormancy are also addressed. The persistence of volunteer canola seed in the soil seedbank is a result of the induction of canola seed into secondary dormancy under adverse environmental conditions such as low temperature or low light. Genetics is a major influencing factor on absolute secondary dormancy (∼50%) in canola. Plant hormones abscisic acid and gibberellic acid and their interactions also influence dormancy with highly dormant genotypes having increased abscisic acid concentration in the seed. Seed sugars, seed storage proteins, glucosinolate content, and growth habit are all additional factors affecting absolute dormancy in B. napus. Furthermore, maternal environmental conditions affect dormancy levels. In addition to genetic, physiological, and environmental factors, farming practices such as harvest timing, and tillage regimes can influence secondary dormancy of canola seed that has entered the seedbank unintentionally. Given the documented high heritability of secondary dormancy, it is feasible to reduce secondary dormancy in canola cultivars; however, consideration of all interacting factors must be given.

Development of optimized Verticillium longisporum inoculation techniques for canola (Brassica napus)

Verticillium stripe, caused by Verticillium longisporum, is an emerging soilborne disease of canola (Brassica napus) in Canada. Improved inoculation protocols will facilitate study of Verticillium stripe and its management. Two inoculation techniques, a root-dip method at two inoculum concentrations and a grain inoculation method at four inoculum concentrations, were compared under greenhouse conditions with the canola cultivars ‘45H31’, ‘CS2000’ and ‘Westar’. Symptoms of Verticillium stripe appeared at early growth stages following root dip inoculation, resulting in seedling mortalities of up to 19.7%, 39.5% and 33.3% for ‘CS2000’, ‘45H31’ and ‘Westar’, respectively, at 35 days post-inoculation. Plants inoculated by the root-dip method incurred much greater mortality at the high versus low inoculum concentration. In the surviving adult plants, ‘45H31’ was moderately resistant while ‘CS2000’ was more susceptible to V. longisporum. The grain inoculation method did not cause early-stage mortality, although Verticillium stripe severity at the adult stage was significantly different between control and high inoculum concentrations for all cultivars. In addition, plant dry weight and height decreased as inoculum concentration increased. Inoculation of 1-week-old, 2-week-old and 3-week-old seedlings of ‘CS2000’ and ‘Westar’ was also compared by the root-dip method. The impact of host age at inoculation on disease development was not significant, although higher disease severity was observed at later inoculation in ‘CS2000’. The application of grain inoculum may be more suitable for large-scale screening or studies conducted under field conditions.

SNP and Haplotype Variability in the BnP5CR2 Gene and Association with Resistance and Susceptible Cultivars for Sclerotinia sclerotiorum in Brassica napus

Sclerotinia sclerotiorum is a serious disease of oil crop. The P5CR gene is the first gene reported to be associated with resistance to Sclerotinia infection in soybeans, and its closest homologs are located on chromosomes A10 and C09 of Brassica napus. We named these BnP5CR1 and BnP5CR2, respectively. The purpose of this study was to examine the single-nucleotide polymorphism (SNP) and haplotype diversity (Hd) of BnP5CR2 among canola cultivars with different levels of resistance to S. sclerotiorum as well as the expression patterns of BnP5CR2 via an association analysis using resistant and susceptible cultivars of B. napus. The results can thus provide information for future research on the mechanisms of disease resistance to S. sclerotiorum and the breeding of resistant canola cultivars. A total of 95 and 12 polymorphic sites were detected in 1870 and 678 SNP sites in 16 BnP5CR2 and their coding DNA sequence (CDS) population, respectively. A total of six different haplotypes (H1–H6) were inferred from the 16 BnP5CR2 gene-CDS that contributed to the high level of polymorphism. Hd was equal to 0.617, and H1 shared by 10 cultivars was the dominant haplotype, suggesting that H1 is an ancient haplotype among the BnP5CR2 genes. H6 and H5 haplotpypes were present in Nan12R and ZhongYou821, respectively. The expression level in vitro of the BnP5CR2 between Nan12R and ZhongYou821 was significantly different. The upregulated expression of BnP5CR2 in resistant cultivars was higher than that of susceptible cultivars under 6 h, 12 h, 24 h, and 36 h treatments of pathogen stress, among which the expression level was significantly increased at 6 h, 12 h and 36 h in resistant cultivars, and the difference reached a highly significant level at 6 h (p &lt; 0.01). The two cultivars with clear differences in expression features possessed different BnP5CR2 gene-CDS-haplotypes, indicating that gene-CDS-haplotype diversity may have greater power than SNPs for the detection of causal genes for quantitative traits.